Electronics Projects/Circuits

<div dir="ltr" style="text-align: left;" trbidi="on"> <div dir="ltr" style="text-align: left;" trbidi="on"> <br /> <ol style="text-align: left;"> <li><a href="http://www.ecestream.com/2014/05/seven-segment-intruder-alarm-circuit.html">Seven Segment Intruder Alarm Circuit</a></li> <li><a href="http://www.ecestream.com/2015/05/speed-checker-for-highways-circuit.html">Speed Checker for Highways</a></li> <li><a href="http://www.ecestream.com/2014/05/sensitive-intruder-alarm-circuit.html">Sensitive Intruder Alarm Circuit</a></li> <li><a href="http://www.ecestream.com/2014/05/electronic-fuse-circuit.html">Electronic Fuse Circuit</a></li> <li><a href="http://www.ecestream.com/2014/11/simple-code-lock.html">Simple Code Lock</a></li> <li><a href="http://www.ecestream.com/2014/11/smart-fluid-level-indicator.html">Smart Fluid Level Indicator</a></li> <li><a href="http://www.ecestream.com/2014/11/bass-and-treble-for-stereo-system.html">Bass and Treble for Stereo System</a></li> <li><a href="http://www.ecestream.com/2014/11/designing-rf-probe.html">Designing An RF Probe</a></li> <li><a href="http://www.ecestream.com/2014/11/protection-for-your-electrical.html">Protection For Your Electrical Appliances</a></li> <li><a href="http://www.ecestream.com/2014/11/multipurpose-circuit-for-telephones.html">Multipurpose Circuit for Telephones</a></li> <li><a href="http://www.ecestream.com/2014/11/musical-bell-circuit.html">Musical Bell Circuit</a></li> <li><a href="http://www.ecestream.com/2014/11/obstacle-avoiding-robot.html">Obstacle Avoiding Robot</a></li> <li><a href="http://www.ecestream.com/2014/11/rain-alarm-circuit.html">Rain Alarm Circuit</a></li> <li><a href="http://www.ecestream.com/2014/11/pwm-lamp-dimmer.html">PWM Lamp Dimmer</a></li> <li><a href="http://www.ecestream.com/2014/11/power-failure-alarm.html">Power Failure Alarm</a></li> <li><a href="http://www.ecestream.com/2014/11/mobile-incoming-call-indicator.html">Mobile Incoming Call Indicator</a></li> <li><a href="http://www.ecestream.com/2014/11/automatic-water-tap-faucetvalve.html">Automatic Water Tap (Faucet/Valve) Controller</a></li> <li><a href="http://www.ecestream.com/2015/03/led-chaser-circuit-using-cd4017-and.html">LED Chaser Circuit using CD4017 and NE555 Timer</a></li> <li><a href="http://www.ecestream.com/2015/03/led-vu-meter-with-lm3916.html">LED VU Meter with LM3916</a></li> <li><a href="http://www.ecestream.com/2015/03/triac-based-lamp-dimmer-circuit.html">Triac based lamp dimmer</a></li> <li><a href="http://www.ecestream.com/2015/03/led-chaser-circuit.html">LED Chaser Circuit</a></li> <li><a href="http://www.ecestream.com/2015/04/400va-ac-light-dimmer.html">400VA AC Light Dimmer</a></li> <li><a href="http://www.ecestream.com/2015/04/lm2585-12v-to-24v-step-up-switching-regulator.html">Step-Up Switching Regulator (LM2585 12V to 24V at 1A)</a></li> <li><a href="http://www.ecestream.com/2015/03/picobuck-rgb-led-driver-circuit.html">PicoBuck - RGB LED Driver</a></li> </ol> </div> <hr /> <div class="separator" style="clear: both; text-align: center;"> <img alt="Electronics Projects/Circuits: ECEstream" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgy8kENDqWirl1m-SrSNV8SkHlaUWWISovue11xtapTPZkgGk-NW8XUBPx9F94Ffx2Rp8g_9j0RV36wBDFyOhY-AO2VCOEHJg13AMlnKEB-hEr4ouQLyHyZokkfXoOGpiLUzJJWZVfPS7Fl/s1600/electronics-circuits.gif" title="Electronics Projects/Circuits" /></div> </div>

Electronics Projects/Circuits

Seven Segment Intruder Alarm Circuit Speed Checker for Highways Sensitive Intruder Alarm Circuit Electronic Fuse Circuit Simple Code...

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Speed Checker for Highways

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> While driving on highways, motorists should not exceed the maximum speed limit permitted for their vehicle. However, accidents keep occurring due to speed violations since the drivers tend to ignore their speedometers.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> This speed checker will come handy for the highway traffic police as it will not only provide a digital display in accordance with a vehicle’s speed but also sound an alarm if the vehicle exceeds the permissible speed for the highway.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The system basically comprises two laser transmitter-LDR sensor pairs, which are installed on the highway 100 metres apart, with the transmitter and the LDR sensor of each pair on the opposite sides of the road. The installation of lasers and LDRs is shown in Fig. 1. The system displays the time taken by the vehicle in crossing this 100m distance from one pair to the other with a resolution of 0.01 second, from which the speed of the vehicle can be calculated as follows:</div> <div style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: left;"> <img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnC69yIIQUNDwC1d1xwAFvwJiiTv97kRVi_vRrc1mDNq8arcrVhXm2rfeSJM9OmnDRhE2v4sFiPzRykC8p9ScqzdJvKHh4P_D-rx9qWMQfvZYLZy7NYdLYXwoc9SM1BIi107deKCdFa48I/s1600/Speed+Checker+for+Highways1.jpg" /></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> As per the above equation, for a speed of 40 kmph the display will read 900 (or 9 seconds), and for a speed of 60 kmph the display will read 600 (or 6 seconds). Note that the LSB of the display equals 0.01 second and each succeeding digit is ten times the preceding digit. You can similarly calculate the other readings (or time).</div> <div style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <img alt="Installation of lasers and LDRs" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmkTasmi2-Jcs9jzmHBK-e_hvLQjZyQcjKDWJHRPiNSwLT63-ms-bl9eDAYDHQ9GdHFEF9sHt5PbWHyl40oqKMP0QuhQ5rPBnyTaCFAPKu009vSekXLisSHnLbqrKR5659btlpJQfVa9cO/s1600/Speed+Checker+for+Highways2.jpg" title="Installation of lasers and LDRs" /></div> <div class="separator" style="clear: both; text-align: center;"> <i><span style="color: red;">Fig. 1: Installation of lasers and LDRs on highway</span></i></div> <div style="text-align: justify;"> <br /></div> <div> <div style="text-align: justify;"> <b>Circuit description</b></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Fig. 2 shows the circuit of the speed checker. It has been designed assuming that the maximum permissible speed for highways is either 40 kmph or 60 kmph as per the traffic rule.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The circuit is built around five NE555 timer ICs (IC1 through IC5), four CD4026 counter ICs (IC6 through IC9) and four 7-segment displays (DIS1 through DIS4). IC1 through IC3 function as monostables, with IC1 serving as count-start mono, IC2 as count-stop mono and IC3 as speed-limit detector mono, controlled by IC1 and IC2 outputs. Bistable set-reset IC4 is also controlled by the outputs of IC1 and IC2 and it (IC4), in turn, controls switching on/off of the 100Hz (period = 0.01 second) astable timer IC5.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The time period of timer NE555 (IC1) count-start monostable multivibrator is adjusted using preset VR1 or VR2 and capacitor C1. For 40kmph limit the time period is set for 9 seconds using preset VR1, while for 60kmph limit the time period is set for 6 seconds using preset VR2. Slide switch S1 is used to select the time period as per the speed limit (40 kmph and 60 kmph, respectively). The junction of LDR1 and resistor R1 is coupled to pin 2 of IC1.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Normally, light from the laser keeps falling on the LDR sensor continuously and thus the LDR offers a low resistance and pin 2 of IC1 is high. Whenever light falling on the LDR is interrupted by any vehicle, the LDR resistance goes high and hence pin 2 of IC1 goes low to trigger the monostable. As a result, output pin 3 goes high for the preset period (9 or 6 seconds) and LED1 glows to indicate it. Reset pin 4 is controlled by the output of NAND gate N3 at power-on or whenever reset switch S2 is pushed.</div> </div> <div style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1cxbRgmpTTVhunwQwRz9QBv8rGNREi9Q5b8Y3XQvOOQg-M2MRAKwDUIAvCdHEcFW3R1wrG4dtrv7mfaGxNoVUKjo0RU7dzlmi2JLvOKXGTZVZzbWfKSR46F4-3DO659r4evoaNwpWX_nT/s1600/Speed+Checker+for+Highways3.jpg" /></div> <div style="text-align: justify;"> <br /></div> <div> <div style="text-align: justify;"> For IC2, the monostable is triggered in the same way as IC1 when the vehicle intersects the laser beam incident on LDR2 to generate a small pulse for stopping the count and for use in the speed detection. LED2 glows for the duration for which pin 3 of IC2 is high.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The outputs of IC1 and IC2 are fed to input pins 2 and 1 of NAND gate N1, respectively. When the outputs of IC1 and IC2 go high simultaneously (meaning that the vehicle has crossed the preset speed limit), output pin 3 of gate N1 goes low to trigger monostable timer IC3. The output of IC3 is used for driving piezobuzzer PZ1, which alerts the operator of speed-limit violation. Resistor R9 and capacitor C5 decide the time period for which the piezobuzzer sounds.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The output of IC1 triggers the bistable (IC4) through gate N2 at the leading edge of the count-start pulse. When pin 2 of IC4 goes low, the high output at its pin 3 enables astable clock generator IC5. Since the count-stop pulse output of IC2 is connected to pin 6 of IC4 via diode D1, it resets clock generator IC5.  IC5 can also be reset via diode D2 at power-on as well as when reset switch S2 is pressed.</div> </div> <div style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> </div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLOXUfXwj1vvNYagxWW51Z6Ax1-J00WKadTZEGh7TwOxfN1jlK-643kXtEukGh4-LPyvjf-zkGXjSnyg3z6vmBzJEInrI9gu2j_xiSe31eHEuzK_LV7Yshkybksj1ihfyhgrWB7FU1KJB1/s1600/Speed+Checker+for+Highways4.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Circuit of Speed Checker for Highway" border="0" height="416" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLOXUfXwj1vvNYagxWW51Z6Ax1-J00WKadTZEGh7TwOxfN1jlK-643kXtEukGh4-LPyvjf-zkGXjSnyg3z6vmBzJEInrI9gu2j_xiSe31eHEuzK_LV7Yshkybksj1ihfyhgrWB7FU1KJB1/s640/Speed+Checker+for+Highways4.jpg" title="Circuit of Speed Checker for Highway" width="640" /></a></div> <div class="separator" style="clear: both; text-align: center;"> <i><span style="color: red;">Fig. 2: Circuit of speed checker for highway</span></i></div> <div style="text-align: justify;"> <br /></div> <div> <div style="text-align: justify;"> IC5 is configured as an astable multivibrator whose time period is decided by preset VR3, resistor R12 and capacitor C10. Using preset VR1, the frequency of the astable multivibrator is set as 100 Hz. The output of IC5 is fed to clock pin 1 of decade counter/7-segment decoder IC6 CD4026.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> IC CD4026 is a 5-stage Johnson decade counter and an output decoder that converts the Johnson code into a 7-segment decoded output for driving DIS1 display. The counter advances by one count at the positive clock signal transition.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The carry-out (Cout) signal from CD4026 provides one clock after every ten clock inputs to clock the succeeding decade counter in a multidecade counting chain. This is achieved by connecting pin 5 of each CD4026 to pin 1 of the next CD4026.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> A high reset signal clears the decade counter to its zero count. Pressing switch S2 provides a reset signal to pin 15 of all CD4026 ICs and also IC1 and IC4. Capacitor C12 and resistor R14 generate the power-on-reset signal.</div> </div> <div style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <img alt="Power Supply" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCF4_6HegKOkf_AuP74JEa8hstIQKqdAc5qvjwaY9xeY65lMe1v8tK21VjVfemCIw_felM1XsKN7anU7o4UvaSgh27YTvBFh-CVgepKu3vdUPDx0hTTaU3w7GzFQgvETBtsPVH5BlOwOa1/s1600/Speed+Checker+for+Highways5.jpg" title="Power Supply" /></div> <div class="separator" style="clear: both; text-align: center;"> <i><span style="color: red;">Fig. 3: Power supply</span></i></div> <div style="text-align: justify;"> <br /></div> <div> <div style="text-align: justify;"> The seven decoded outputs ‘a’ through ‘g’ of CD4026s illuminate the proper segment of the 7-segment displays (DIS1 through DIS4) used for representing the decimal digits ‘0’ through ‘9.’ Resistors R16 through R19 limit the current across DIS1 through DIS4, respectively.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Fig. 3 shows the circuit of the power supply. The AC mains is stepped down by transformer X1 to deliver the secondary output of 15 volts, 500 mA. The transformer output is rectified by a bridge rectifier comprising diodes D3 through D6, filtered by capacitor C14 and regulated by IC11 to provide regulated 12V supply. Capacitor C15 bypasses any ripple in the regulated output. Switch S3 is used as the ‘on’/‘off’ switch. In mobile application of the circuit, where mains 230V AC is not available, it is advisable to use an external 12V battery. For activating the lasers used in conjunction with LDR1 and LDR2, separate batteries may be used.</div> </div> </div>

Speed Checker for Highways

While driving on highways, motorists should not exceed the maximum speed limit permitted for their vehicle. However, accidents keep occurr...

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LM2585 12V to 24V at 1A Step-Up Switching Regulator

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> <b>Description</b></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> This is a DC-DC step-up converter based on LM2585-ADJ regulator manufactured by Texas Instruments. This IC was choosen for it's simplicity of use, requiring minimal external components and for it's ability to control the output voltage by defining the feedback resistors (R1, R2). NPN switching/power transistor is integrated inside the regulator and is able to withstand 3A maximum current and 65V maximum voltage. Switching frequency is defined by internal oscillator and it's fixed at 100KHz.<br /> <br /></div> <div style="text-align: justify;"> <div class="separator" style="clear: both; text-align: center;"> <img alt="LM2585 Pin Diagram" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiILgEn18AA0ek9FCuf-JDZ_l3JneH2tucfb0y3QzDp9yJv27VP7eeagoWtdGh3veh-qruH00-J3U89xf0uNRVgIlHmCdN9qkhwaosxTgeQ0hFrYFjv9sUaBr_lm396AxINbXcWNOVDSLmK/s1600/LM2585_pinout.png" title="LM2585" /></div> <br /></div> <div style="text-align: justify;"> Additional features include soft-start circuit to eliminate current spikes during start-up and internal current limit. Output voltage regulation is 4% within input voltage and load specifications.</div> <div style="text-align: justify;"> <br /> <b>Schematic</b><br /> <br /> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNJP2JIpnc7r3SOmkJYSX-48PsRVIxvhOC3gU2dMxVgW4U4F0BJNcCQwtIBePps_1Ald8HtrYcOGXA3obSnD5T4Xh1c4X08JJHo_IDyvEJFmUYX_Y1q5cstZSysX8-3rpb6-OTKtJWlIBd/s1600/LM2585_schematic.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="LM2585 Step-up switching regulator" border="0" height="230" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNJP2JIpnc7r3SOmkJYSX-48PsRVIxvhOC3gU2dMxVgW4U4F0BJNcCQwtIBePps_1Ald8HtrYcOGXA3obSnD5T4Xh1c4X08JJHo_IDyvEJFmUYX_Y1q5cstZSysX8-3rpb6-OTKtJWlIBd/s1600/LM2585_schematic.png" title="LM2585 Step-up switching regulator" width="640" /></a></div> <br /> <br /></div> <div style="text-align: justify;"> <b>Specifications</b></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Vin<span class="Apple-tab-span" style="white-space: pre;"> </span>            10-15V DC </div> <div style="text-align: justify;"> Vout<span class="Apple-tab-span" style="white-space: pre;"> </span>          24V</div> <div style="text-align: justify;"> Iout<span class="Apple-tab-span" style="white-space: pre;"> </span>            1A</div> <div style="text-align: justify;"> frequency<span class="Apple-tab-span" style="white-space: pre;"> </span>  100KHz</div> <div style="text-align: justify;">  <span class="Apple-tab-span" style="white-space: pre;"> </span> </div> <div style="text-align: justify;"> Schematic is a simple boost topology arrangement based on datasheet. Input capacitors and diode should be placed close enough to the regulator to minimize inductance effects of pcb traces. IC1, L1, D1, C1, C2 and C5, C6 are the main parts used in voltage conversion. Capacitor C3 is a high frequency bypass capacitor and should be placed as close to IC1 as possible.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> All components are selected for their low loss characteristics. So capacitors selected have low ESR and inductor selected has low DC resistance.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> At maximum output power there is significant heat produced by IC1 and for that reason we mounted it directly on the ground plane to achieve maximum heat radiation.</div> </div>

LM2585 12V to 24V at 1A Step-Up Switching Regulator

Description This is a DC-DC step-up converter based on LM2585-ADJ regulator manufactured by Texas Instruments. This IC was choosen for...

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400VA AC Light Dimmer

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> <b>Description</b></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> This is a simple TRIAC AC load dimmer used to control the power of a resistive load such as incandescent lamp or heater element. The max load it can handle is 400VA. Such a circuit is often found on cheap commercial light dimmers and is proven to work reliable for the rated power.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The circuit is working by controlling the phase of the 220VAC voltage allowing the load to be powered for less than 360º of the full sine wave. Powering the load for smaller period than full sine wave delivers less power, so it has a dimming effect on the load.</div> <div style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <img alt="400VA AC Light Dimmer" border="0" height="284" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGR2pW3upA0DImlV0d_KxIIfhfSB1hfgLusiwIn8JAGBnNsdbgVmp3ZeneyIrfKL_7qEx_OxJvBtQcxUpvyyfmuL20eKHicawl8TmY9q8WAlOMxYFo399R-zrThW3ys7pyWeEBJLj9LIp_/s1600/ac_dimmer1.png" title="AC Light Dimmer" width="400" /></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Control is done throught R2 potentiometer which controls the time needed for the C2 to be charged through R1-R2. C2 is charging until it reaches the breakdown voltage of DIAC D1 which then fires the TRIAC T1. Once the TRIAC is contacting the circuit is closed and the load receives power. </div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The rate which C2 charges determinates the point on 220VAC sinewave where it reaches the breadown voltage of DIAC. So, slow C2 charging means that the DIAC conducts at the end of AC period and fast C2 charging means that DIAC conducts at the beggining of AC sine.</div> <div style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnvqjf5r7qYp2E2HwI3DMWNbKgsIaSRoWRQ_iVWJEfT8cALvr0zonmFJNLnRfoKXQog4jwHeo98D8yRoxz05SEra9qtjRu6lNhsdF1XYhfRpDM5_OWjZOz4Az32qgMcbKSVZ-WM7fop_mX/s1600/ac_dimmer.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="400VA AC Light Dimmer" border="0" height="424" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnvqjf5r7qYp2E2HwI3DMWNbKgsIaSRoWRQ_iVWJEfT8cALvr0zonmFJNLnRfoKXQog4jwHeo98D8yRoxz05SEra9qtjRu6lNhsdF1XYhfRpDM5_OWjZOz4Az32qgMcbKSVZ-WM7fop_mX/s1600/ac_dimmer.png" title="400VA AC Light Dimmer Circuit" width="640" /></a></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Components L1 and C1 act as interference suppression filter reducing RF emmitions.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Circuit is directly connected to mains voltage, so lethal voltages present all over the board. Take care! The potentiometer should have a plastic spindle to provide sufficient isolation</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Parts List</b></div> <div style="text-align: justify;"> R1<span class="Apple-tab-span" style="white-space: pre;"> </span>3.9K - 1/4W</div> <div style="text-align: justify;"> R2<span class="Apple-tab-span" style="white-space: pre;"> </span>470K linear potentiometer</div> <div style="text-align: justify;"> C1<span class="Apple-tab-span" style="white-space: pre;"> </span>33nF / 400V capacitor</div> <div style="text-align: justify;"> C2<span class="Apple-tab-span" style="white-space: pre;"> </span>100nF polyester capacitor</div> <div style="text-align: justify;"> L1<span class="Apple-tab-span" style="white-space: pre;"> </span>19 turns of 0.8mm enamel wire on 4mm ferrite core</div> <div style="text-align: justify;"> D1<span class="Apple-tab-span" style="white-space: pre;"> </span>DB4 diac</div> <div style="text-align: justify;"> T1<span class="Apple-tab-span" style="white-space: pre;"> </span>BTA10-400B Triac</div> <div style="text-align: justify;">  <span class="Apple-tab-span" style="white-space: pre;"> </span>heatsink for T1</div> <div style="text-align: justify;">  <span class="Apple-tab-span" style="white-space: pre;"> </span>PCB screw terminals</div> </div>

400VA AC Light Dimmer

Description This is a simple TRIAC AC load dimmer used to control the power of a resistive load such as incandescent lamp or heater el...

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PicoBuck - RGB LED Driver

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> The PicoBuck is a small and inexpensive 3-channel LED driver. It employs constant-current buck driving which approaches an efficiency of 95% (theoretical). It's based on AL8805 LED Lighting Buck Driver from Diodes Inc.<br /> <br /></div> <div style="text-align: justify;"> </div> <div style="text-align: justify;"> <b><span style="color: #3d85c6;">Description</span></b></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The PicoBuck supports a wide range of input voltages (6v to 20v) which may be connected to the VIN header. It has three inputs for each driver channel, labeled IN1, IN2, and IN3 which may be driven with standard 3.3v or 5v logic. LEDs are connected to the outputs of the driver, OUT1 through OUT3. Each channel of an RGB LED must be connected to the driver separately: this driver, like most buck drivers, does not support common-anode or common-cathode RGB LEDs.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Each channel of the PicoBuck can drive an LED at 350mA on the standard model. The driving current is set by a small current sensing resistor populated on the board. If you need to drive LEDs at higher or lower currents, just swap out the current sensing resistor to achieve your desired current. You can calculate the value of your current sensing resistor with the AL8805 spreadsheet.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b><span style="color: #3d85c6;">Usage</span></b></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Digital Mode:</b> To use digital drive mode, apply a standard 3.3v or 5v PWM signal to any of the 3 inputs. This method gives good brightness resolution over the entire range of brightness when using 8 to 10 bit PWM.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Analog Mode:</b> To use analog mode, apply an analog voltage between 0v and 2.5v to any of the 3 inputs. This analog voltage controls how much current the LED is driven at, up to the current set by the current-limiting resistor. Note that the analog method is not effective for the last 20% of current—at this point, the current drops to zero.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Alternatively, you may employ a compound approach using analog dimming for high brightness and PWM dimming for low brightness. This method achieves optimal brightness resolution with minimal flicker, but is more challenging to implement in software.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b><span style="color: #3d85c6;">Circuit Diagram</span></b></div> <div style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjscw-kXug_fo07xrILCCUW8KJpRrvhmObZo51iFjrNUGL-GYdTFSWDA5i3g3SZRaS8LJwwTsI4V4NdEIbiL1ktK6OGLKruqcWdYSG4xL8CLZamo5YtGxX723vRo5d-pvLZ6VS68RlFwv_/s1600/PicoBuck+-+RGB+LED+Driver.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="PicoBuck - RGB LED Driver" border="0" height="295" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjscw-kXug_fo07xrILCCUW8KJpRrvhmObZo51iFjrNUGL-GYdTFSWDA5i3g3SZRaS8LJwwTsI4V4NdEIbiL1ktK6OGLKruqcWdYSG4xL8CLZamo5YtGxX723vRo5d-pvLZ6VS68RlFwv_/s1600/PicoBuck+-+RGB+LED+Driver.png" title="PicoBuck - RGB LED Driver Circuit" width="400" /></a></div> </div>

PicoBuck - RGB LED Driver

The PicoBuck is a small and inexpensive 3-channel LED driver. It employs constant-current buck driving which approaches an efficiency of 9...

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LED Chaser Circuit

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> The led chaser is build on a perfboard using 10 leds, CD4017 decade counter, a 555 timer configured in astable mode and some additional components. The circuit is really simple. On the left we see the NE555 timer IC configured in astable mode, producing a squarewave which frequency is defined by the resistor array and C1 capacitor. Trimming R4 we are able to change the velocity of the running LEDs.<br /> <br /></div> <div style="text-align: justify;"> </div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrtiKkSRHRAKEEadQWt-h5FgCiPe7YNkCGkWoJLsXsdg3BfmrYxso0VFOgOoiF2FUYr2dBBgO64LX8BpPqnkWGSCnh66S2AE-Wsxx7IoSK3ZIQgS6ki-CGFcmCCuKfXKEQS566RKFSxu90/s1600/LED+Chaser.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="LED Chaser Circuit" border="0" height="263" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrtiKkSRHRAKEEadQWt-h5FgCiPe7YNkCGkWoJLsXsdg3BfmrYxso0VFOgOoiF2FUYr2dBBgO64LX8BpPqnkWGSCnh66S2AE-Wsxx7IoSK3ZIQgS6ki-CGFcmCCuKfXKEQS566RKFSxu90/s1600/LED+Chaser.png" title="LED Chaser Circuit" width="400" /></a></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The output of NE555 timer is feed to CLK of 4017 decade counter. So in practice decade counter is counting the pulses that NE555 produces and for each pulse one LED is lighting. On the next pulse the first LED is shut of and the next is light up. This continues until the last led is ON and the sequence continues from the first one.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> So if you arrange the LED in a closed shape the LEDs will spin forever.</div> </div>

LED Chaser Circuit

The led chaser is build on a perfboard using 10 leds, CD4017 decade counter, a 555 timer configured in astable mode and some additional co...

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Triac based lamp dimmer

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> Triac based Indecent lamp dimmer is a simple circuit and it does not requires additional power supply, works directly with 110V AC or 230V AC.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> It is a low cost dimmer circuit for adjusting the light brightness of incandescent, Halogen Lamp, Light Bulb load up to 250 W.<br /> <br /></div> <div style="text-align: justify;"> </div> <div style="text-align: justify;"> <b><span style="color: #3d85c6;">Features:</span></b></div> <div style="text-align: justify;"> </div> <ul> <li>Input supply: 230 VAC or 110 VAC</li> <li>Output: 250 W</li> <li>Triac controlled</li> <li>On board Potentiometer for adjusting level</li> <li>Power Battery Terminal (PBT) for easy input / output connection</li> <li>Four mounting holes of 3.2 mm each</li> <li>PCB dimensions 40 mm x 34 mm</li> </ul> <div> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <img alt="Triac based lamp dimmer" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTuWjhFVZMUQlz765ehCfm3WpoX5rs8ScnmTDeCwa23cq_OH0Qpn6oMxMPwBAMHvQhbaOFOXsn4yUsqUi4X9Js9ho1Wwx0lewacIGUbIngaY8DnvnBTfPxT5GGt8oq6VmN1hB40lkosiwt/s1600/Triac+based+lamp+dimmer.jpg" title="Triac based lamp dimmer" /></div> <br /> <div style="text-align: justify;"> <b><span style="color: #3d85c6;">Circuit description</span></b></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> This kit consists of BT 136 Triac, resistors and capacitor.  CN1 connector is for Load connections and CN2 connector for power supply connections.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>BT136:</b> It is a sensitive gate Triac, used in general purpose bidirectional switching and phase control applications where high sensitivity is required.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>DB3:</b> It is a DIAC that functions as a trigger diode with a fixed voltage reference.  It can be used in conjunction with Triac for simplified gate control circuits or as a starting element in fluorescent lamp ballasts</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b><span style="color: #3d85c6;">Working principle</span></b></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> This kit is used as a Light dimmer kit.  It is used to adjust the brightness of the Halogen Lamp, Light Bulb up to 250 W.  A power supply of 230 or 110 VAC is supplied to the kit at CN 2 connector and a light bulb is connected at the CN 1 connector. Using the POT we can adjust the brightness of the bulb.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b><span style="color: #3d85c6;">Applications</span></b></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> It is used to adjust the brightness of incandescent, halogen lamp, light bulb up to 250 W.<br /> <br /> <b><span style="color: #3d85c6;">Parts Required</span></b><br /> <br /> <div class="separator" style="clear: both; text-align: center;"> <img border="0" height="313" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5P8Cu65q9pTZIeDB5zP45QBGGlc25jsshg5_xfwv9AjUnETS_h5SaKPW-xSf5lvtvEN_3TBg8eYDX36URvf532M4J_2391e3sJPbQy_TXHVJnlQ10_O1r5V1k-G8N6aeDa9uZio9wLJVf/s1600/BOM.jpg" width="400" /></div> </div> </div>

Triac based lamp dimmer

Triac based Indecent lamp dimmer is a simple circuit and it does not requires additional power supply, works directly with 110V AC or 230V...

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LED VU Meter with LM3916

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> LM3916 is a dedicated IC for VU LED meter. Unlike LM3915 which have 3dB step between voltage levels, the LM3916 have nonlinear steps: -20, -10, -7, -5, -3, -1, 0, +1, +2, +3db, just like old school analog VU meters.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The LM3916 can be feed with AC signal without any rectification, it implement a precision full wave rectification.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The LEDs are connected via sockets J3 to J12 (only one row LEDs is shown on the schematic).<br /> <br /></div> <div style="text-align: justify;"> </div> <div style="text-align: justify;"> The schematic needs bipolar power supply to work correctly, but the negative rail can be as low as -5V or even -3.3V. The positive rail must be bellow +25V and combined voltage of negative and positive rails must not exceed 36V. The minimum positive rail voltage depends on the voltage of the LEDs. For example if the LED have 1.9V forward voltage and we have 7 LEDs on one pin, then the minimum positive voltage will be 7*1.9V + 1.5V (drop voltage at LM3916) = 14.8V. The green LEDs usually have little higher forward voltage - 2.2V - 2.4V, so +18V will be sufficient in most cases.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The LEDs current is determined by R1_REF, and with 2.2k resistance it will be 5 - 6 mA.</div> <div style="text-align: justify;"> The formula is Iled = 10 * (1.2V / R1_REF).</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> IC2 is connected as precision full wave rectifier and can be any general purpose dual op-amp - TL072, TL082, LF353.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The output mode can be set with 3-pin jumper JP1. Shorting pins 1-2 will set the bar mode and shorting pins 2-3 will set the dot mode.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The max input voltage of the LM3916 is set to 1.2V, and with R8-R7 we can adjust the input level.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The color of the LEDs is your choice. I used green LEDs for negative levels, yellow for 0dB and red for positive levels. For this project I bought transparent rectangular LEDs, but they have two drawbacks. First - when one column lights up the adjacent columns also significantly lights up. My solution was to paint the sides of the LEDs with black marker. There also can be used a black tape around the entire collumn.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Second drawback is that because of the transparency, the LEDs emit light from one point, which is not very pleasant. The solution here was to rasp the top side of the LEDs with rough file, so the light to diffuse more even.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b><span style="color: #3d85c6;">Circuit Diagram</span></b></div> <div style="text-align: justify;"> <div class="separator" style="clear: both; text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-cgctlL2_uQ0DcvW2R-OO-BneoAUlIIGc4_fJVi8UwDVbHNa9U4tx0Q2PClIrHYQWldlmZBcU-O6Tng-zy2JaUv9qlcUiU3pAcw1gwVIyy9Q-yRxMv1pf1LfUnynzF0A7o68zIWxKuQNc/s1600/LED_VU_Meter_(schematic).png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="LED VU Meter with LM3916 Circuit" border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-cgctlL2_uQ0DcvW2R-OO-BneoAUlIIGc4_fJVi8UwDVbHNa9U4tx0Q2PClIrHYQWldlmZBcU-O6Tng-zy2JaUv9qlcUiU3pAcw1gwVIyy9Q-yRxMv1pf1LfUnynzF0A7o68zIWxKuQNc/s1600/LED_VU_Meter_(schematic).png" title="LED VU Meter with LM3916 Schematic" width="400" /></a></div> </div> <div class="separator" style="clear: both; text-align: center;"> </div> </div>

LED VU Meter with LM3916

LM3916 is a dedicated IC for VU LED meter. Unlike LM3915 which have 3dB step between voltage levels, the LM3916 have nonlinear steps: -20,...

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LED Chaser Circuit using CD4017 and NE555 Timer

<div dir="ltr" style="text-align: left;" trbidi="on"> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg92ljnBPTQxdItXL2JaPGs2Yuf1j-mDjr321DCN62MJ_knQsmWLv6ROx7m9JKFyQvHuAPeoRWDouqrxC2yQo4OHMZZd1JyMkWlJvvonI8SqATqJ5YvhRTPnxAiYh2D54F39p8nkM7nx3IW/s1600/Led+Chaser+Circuit.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="LED-Chaser-Circuit-ecestream" border="0" height="304" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg92ljnBPTQxdItXL2JaPGs2Yuf1j-mDjr321DCN62MJ_knQsmWLv6ROx7m9JKFyQvHuAPeoRWDouqrxC2yQo4OHMZZd1JyMkWlJvvonI8SqATqJ5YvhRTPnxAiYh2D54F39p8nkM7nx3IW/s1600/Led+Chaser+Circuit.jpg" title="LED Chaser Circuit" width="320" /></a></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> You can build simple <a href="http://www.ecestream.com/2014/11/light-emitting-diodes-leds.html" target="_blank">LED</a> chaser circuits using CD4017 and NE555 timer. There are hundreds of projects in the internet for making such simple LED chaser circuits.</div> <div style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiAO1ixtqFOWO-LHC_lKYv8h7HKzYxqzwgP5UZLZdl71Q-EChJTjFWoendtzIkDdDrvlsKBhwl7jHV5BwzAXDD3_0iC8WHthsNfaSAEx3cLYrmGkDkwLnoi51unLViKNNDv8M8NfMc_MwFI/s1600/Led+Chaser+Circuit+Diagram.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="LED-Chaser-Circuit-ecestream" border="0" height="331" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiAO1ixtqFOWO-LHC_lKYv8h7HKzYxqzwgP5UZLZdl71Q-EChJTjFWoendtzIkDdDrvlsKBhwl7jHV5BwzAXDD3_0iC8WHthsNfaSAEx3cLYrmGkDkwLnoi51unLViKNNDv8M8NfMc_MwFI/s1600/Led+Chaser+Circuit+Diagram.jpg" title="LED Chaser Circuit using CD4017 and NE555 Timer" width="400" /></a></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> This is the schematic for a very basic 10 LED chaser circuit. It used a 10 uF <a href="http://www.ecestream.com/2014/11/capacitor.html" target="_blank">capacitor</a> for C1. The 10K pot can reduce the flash speed from not moving to whatever minimum time constant is possible with the C1 value you choose. Don’t bother with ultra-bright LEDs for these “chaser” projects as cheaper, lower millicandela (mcd) LEDS work fine. I favor blue and green LEDS. The 4017 decade counter is a fabulous part and can be driven to flash a row of <a href="http://www.ecestream.com/2014/11/light-emitting-diodes-leds.html" target="_blank">LEDs</a> with a <a href="http://www.ecestream.com/2014/11/the-555-timer.html" target="_blank">555 timer</a> chip or a discrete <a href="http://www.ecestream.com/2014/12/bipolar-junction-transistors-bjts.html" target="_blank">BJT</a> multivibrator.</div> </div>

LED Chaser Circuit using CD4017 and NE555 Timer

You can build simple LED chaser circuits using CD4017 and NE555 timer. There are hundreds of projects in the internet for making such...

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Automatic Water Tap (Faucet/Valve) Controller

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> Presented here is a <i>simple electronic circuit which can control the valve operation</i> by sensing valid-movements with the help of a <i>Passive Infrared (PIR) motion sensing module</i>. In practice, automatic taps are presence sensors and not motion sensors. They employ “Active Infrared” technology which senses “presence” and not “movement” of objects. However, here an unorthodox “Passive Infrared” technology is used to realize the 6V DC powered smart faucet controller circuit.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Schematic of the Water Tap/Valve Controller Circuit</b></div> <div style="text-align: justify;"> <b><br /></b></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGY6dGnIZdsPec6E6OPREd4UIjX4a9sHWzMNVvi7CL0mw50sUKgFrgfaSeIP_cx1-87tnMhybj_lrJXmBdx9QImwyv6hj0nhf-oOqSPQRXwpfKd_5FpyZhZdiW1T_6An6_n1bOUIrIsqPz/s1600/Automatic+Water+Tap+Controller.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGY6dGnIZdsPec6E6OPREd4UIjX4a9sHWzMNVvi7CL0mw50sUKgFrgfaSeIP_cx1-87tnMhybj_lrJXmBdx9QImwyv6hj0nhf-oOqSPQRXwpfKd_5FpyZhZdiW1T_6An6_n1bOUIrIsqPz/s1600/Automatic+Water+Tap+Controller.png" /></a></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Smart Valve Controller is a combination of four key components</b></div> <div style="text-align: justify;"> <ul> <li>motion sensor with control electronics</li> <li>solenoid valve</li> <li>power source</li> <li>and the faucet</li> </ul> </div> <div style="text-align: justify;"> As stated, at the heart of the circuit is a Passive Infrared (PIR) module. PIR sensor is a pyroelectric device that detects motion by measuring changes in the infrared levels emitted by surrounding objects. Pyroelectric devices, such as the PIR sensor, have elements made of a crystalline material that generates an electric charge when exposed to infrared radiation. The changes in the amount of infrared striking the element change the voltages generated, which are measured by an onboard amplifier.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The device contains a special filter called a Fresnel lens, which focuses the infrared signals onto the element. The PIR Sensor requires a ‘warmup’ time in order to function properly. This is due to the settling time involved in ‘learning’ its environment. this could be anywhere from 10 to 60 seconds. During this time there should be as little motion as possible in the sensors field of view. There is a variable resistor (P1) on the PIR sensor module to control the ‘ON’ delay time for the sensor. Turning this variable resistor clockwise will give longer ‘ON’ delay time while turning anticlockwise will reduce the ‘ON’ delay time. The PIR sensor has distance range of approximately 3 to 7 meters. It is possible to adjust distance of detection with the help of the second variable resistor (P2) on the PIR sensor module.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Likewise, there is a 2-position jumper point (JP) is included in the PIR sensor module. The sensor is active HIGH (LOW in idle state) when jumper is in either position. In “retrigger” (H) position, output remains HIGH when sensor is triggered repeatedly. In “normal” (L) position, output goes HIGH then LOW when triggered. Continuous motion results in repeated HIGH/LOW pulses.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The motion sensor with control electronics circuitry is very simple and self-explanatory. Output of the PIR sensor module (SEN1) is here connected to a ‘traditional’ monostable multivibrator (MMV) wired around the ubiquitous timer chip NE555 (IC1) . Output of IC1 controls the solenoid valve through a 6V electromagnetic relay attached to J1.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Two LEDs (LED 1 & LED2) are added as system status indicators. SPDT switch S1 is the “Auto/Manual” Mode Selector. “Push – to – On” switch S2 can be used for manual operation of the faucet. Prototype tested with four 1.5V AA cells (1.5Vx4 = 6V).</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Note</b></div> <div style="text-align: justify;"> <ol> <li>Remember to set delay time & detection range of the system as low as possible by adjusting the preset pots P1 & P2 of the PIR sensor module. Removing the fresnel lens, collimation and screening by means of a piece of a suitable electrical conduit with a length of 2 to 3 cm is not a bad idea to reduce the field of view of the PIR sensor module. Place the jumper (JP) in “Normal” mode!</li> <li>Why a PIR sensor based design? PIR sensor is small, inexpensive, low power, rugged,is easy to interface with, and is easy to use. When motion is detected the PIR sensor outputs a high signal on its output pin, which can either be read by an MCU or drive a transistor to switch a higher current load.</li> </ol> </div> <div style="text-align: justify;"> <b>Parts List</b></div> <div style="text-align: justify;"> <ul> <li>SEN 1 : PIR sensor module</li> <li>T1 : BC547</li> <li>LED1 : 5mm Green</li> <li>LED2: 5mm Red</li> <li>D1 : 1N4007</li> <li>IC1 : NE555</li> <li>R1, R2: 1K</li> <li>R3 : 100K</li> <li>R4 : 470R</li> <li>C1,C2 : 100nF</li> <li>C3 : 100uF/16V</li> <li>S1 : SPST On/Off</li> <li>S2 : Push -To – On</li> <li>J1: 2-Pin male header</li> <li>Relay: 6VDC /SPST Electromagnetic Relay</li> </ul> </div> </div>

Automatic Water Tap (Faucet/Valve) Controller

Presented here is a simple electronic circuit which can control the valve operation by sensing valid-movements with the help of a Passive...

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Mobile Incoming Call Indicator

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> <span style="font-family: inherit;">This circuit will give a visual indication if placed near a mobile phone even if the ringer is deactivated. </span><span style="font-family: inherit;">When a call is coming to the mobile phone, the transmitter inside it becomes activated. The frequency of the transmitter is around 900MHz. The coil L1 picks up these oscillations by induction and feds it to the base of Q1. This makes the transistor Q1 activated. Since the Collector of Q1 is connected to the pin 2 of IC1 (NE555), the IC1 is triggered to make the LED connected at its output pin (pin 3) to blink. The blinking of the LED is the indication of incoming call.</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div style="text-align: justify;"> </div> <div style="text-align: justify;"> <span style="font-family: inherit;"><b>Circuit diagram with Parts list</b><span style="color: red;"> </span></span></div> <div style="text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFUE_o5mDq1sn6MmJr-XFVa7L4mb2qHCqVf5ZJiGeKah7gkRS0tDkkhZvvg582zkcMRh013kYB0-jxS2nIzsWksK32Ysv4TKzcoQiPtYfWV_HxiWV_3EU8xLaUjMGFItvRcDqYcDbtm7Dd/s1600/MOBILE+INCOMING+CALL+INDICATOR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: inherit;"><img border="0" height="356" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFUE_o5mDq1sn6MmJr-XFVa7L4mb2qHCqVf5ZJiGeKah7gkRS0tDkkhZvvg582zkcMRh013kYB0-jxS2nIzsWksK32Ysv4TKzcoQiPtYfWV_HxiWV_3EU8xLaUjMGFItvRcDqYcDbtm7Dd/s1600/MOBILE+INCOMING+CALL+INDICATOR.jpg" width="640" /></span></a></div> <div style="text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div style="text-align: justify;"> <span style="font-family: inherit;"><b>Important Points</b></span></div> <div style="text-align: justify;"> </div> <ul> <li><span style="font-family: inherit;">The coil L1 can be made by making 150 turns of 36 SWG enameled copper wire on a 5mm diameter plastic former. Or you can purchase a 10 uH coil from shop if available.</span></li> <li><span style="font-family: inherit;">The circuit can be powered from a 6V battery.</span></li> <li><span style="font-family: inherit;">Assemble the circuit on a good quality PCB.</span></li> <li><span style="font-family: inherit;">C1 & C3 are to be polyester capacitors.</span></li> <li><span style="font-family: inherit;">The electrolytic capacitor C2 must be rated 10V.</span></li> </ul> </div>

Mobile Incoming Call Indicator

This circuit will give a visual indication if placed near a mobile phone even if the ringer is deactivated.  When a call is coming to the ...

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Power Failure Alarm

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> <span style="font-family: inherit;">This <b><i>power failure alarm circuit</i></b> is a power supply monitoring device that will set off a piezo-speaker when the ac mains mains supply cuts off. It is very helpful to indicate the loss of power supply to some power-critical instruments such as a lifecare device installed in a hospital. Alarm activation at the right time is helpful as it signals that there is a power outage and urgent action should taken to recover the situation by providing an alternative power supply.</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;"><br /></span> <span style="font-family: inherit;">This is a 9V battery operated, low component count, and light weight circuit which can be safely connected to any AC230V outlet. At its heart is the famed little timer chip <i><b>LM555 (IC1)</b></i> configured as an astable multivibrator. Another important component is the “home-baked” opto-coupler (PC1). No bulky power transformer is used here, hence the circuit is “noise-free” (no electromagnetic interference). Further, this makes the enfolding task very simple!</span><br /> <span style="font-family: inherit;"><br /></span> <span style="font-family: inherit;">Although a variety of opto-couplers are available in the market but it may so happen that you may not have one ready at hand when you get a spark and want to check the idea as soon as possible. Fortunately, it is easy to construct one at home using an LED and a </span>photo-transistor<span style="font-family: inherit;">/photo resistor. Just take a small piece of common circuit board and solder the components as indicated here. Keep an eye on the spacing of the components; it should be as close as possible with a slight gap between them. In the prototype one 5mm white LED + 5mm LDR combination was used. After the construction, enclose the opto-coupler in a suitable opaque tube, or cover the whole unit using short-length of heatshrink tube.</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div style="text-align: justify;"> </div> <div class="separator" style="clear: both; text-align: center;"> <span style="font-family: inherit;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghIzkoffgJs8oPwRd3DgvJCt2y_HNDugRoLS-0nrFzvuHulqpskVCX2VlhZFo1Hznk6qytxCTUrW4gyapajknoZDFxa41O60S04MLfnrWsFuIbptNlJ1OUDrmD6hpZW8K1HNYO0xEmC3LX/s1600/POWER+FAILURE+ALARM1.png" /></span></div> <span style="font-family: inherit;"><br /></span> <div style="text-align: justify;"> <span style="font-family: inherit;">The circuit is straight forward. As stated, IC1 is here wired as a gated-astable producing an audio-frequency (AF) output (~1KHz) to drive a standard ordinary/piezo-speaker. Switching of the astable is controlled by the power status detection circuitry built around PC1 and associated components. Switch S1 (SPST) is the system on/off switch, and LED2 (5mm Red) is an optional visual indicator.</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjA_WmYVj4Knl2KxIkfLvH6q1cWOZW7q2r7VLB7G1cd7n6lEp100Clb9Os62HAPD8JvgV57H6IF6Vdt3kPchQUSilvYyJSo6SY0mQJmA7EB_oYgX248vucScRYFm0w-G3hT7llVJr3h71SJ/s1600/POWER+FAILURE+ALARM2.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: inherit;"><img border="0" height="273" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjA_WmYVj4Knl2KxIkfLvH6q1cWOZW7q2r7VLB7G1cd7n6lEp100Clb9Os62HAPD8JvgV57H6IF6Vdt3kPchQUSilvYyJSo6SY0mQJmA7EB_oYgX248vucScRYFm0w-G3hT7llVJr3h71SJ/s1600/POWER+FAILURE+ALARM2.png" width="640" /></span></a></div> <div style="text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div style="text-align: justify;"> <span style="font-family: inherit;"><b>Parts List </b></span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">IC1 : LM555</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">T1 : BC547</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">T2 : BD139</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">D1 : 1N4007</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">LED1 : White 5mm</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">LED 2 : Red 5mm</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">R1 : 100K</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">R2 : 5mm LDR</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">R3 : 1K</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">R4 : 10K</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">R5,R6 : 4K7</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">R7,R8 : 1K</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">C1,C2 : 100nF</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">C3 : 470uF/16V</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">S1 : SPST switch</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">BATT : 9V battery</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;">SPKR : Ordinary/Piezo-Speaker (not active buzzer)</span></div> </div>

Power Failure Alarm

This power failure alarm circuit is a power supply monitoring device that will set off a piezo-speaker when the ac mains mains supply cut...

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PWM Lamp Dimmer

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> <span style="font-family: inherit;">A simple and efficient <i><b>PWM lamp dimmer</b></i> using timer <i>IC NE555</i> is discussed in this article. Earlier linear regulator based dimmers can only attain a maximum efficiency of 50% and are far inferior when compared to the PWM based dimmers which can hit well over 90% efficiency. Since less amount of power is wasted as heat, the switching elements of PWM dimmers require a smaller heat sink and this saves a lot of size and weight. In simple words, the most outstanding features of the PWM based lamp dimmers are high efficiency and low physical size. The circuit diagram of a 12V PWM lamp dimmer is shown below.</span><br /> <span style="font-family: inherit;"><br /></span> <br /> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibYvL0J4GGOAKnJJvwfy6d9xH0usFdcOEP1NRzrjowMjwX0FhWcivW04dK8W_NVRTgwhHkPG8WKYWVeVe-VXtAdhJgOhv-U6YHiaUNQTbYqPJ1rwzp68oc4RtHVpcvdmsYNN_dLc8O_kL6/s1600/PWM+lamp+Dimmer1.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: inherit;"><img border="0" height="545" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibYvL0J4GGOAKnJJvwfy6d9xH0usFdcOEP1NRzrjowMjwX0FhWcivW04dK8W_NVRTgwhHkPG8WKYWVeVe-VXtAdhJgOhv-U6YHiaUNQTbYqPJ1rwzp68oc4RtHVpcvdmsYNN_dLc8O_kL6/s1600/PWM+lamp+Dimmer1.png" width="640" /></span></a></div> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: center;"> </div> <div style="text-align: justify;"> <span style="font-family: inherit;">As you can see, NE555 timer IC which is wired as an astable multivibrator operating at 2.8KHz forms the heart of this circuit. Resistors R1, R2, POT R3 and capacitor C1 are the timing components. Duty cycle of the IC’s output can be adjusted using the POT R3. higher the duty cycle means higher the lamp brightness and lower the duty cycle means lower the lamp brightness. Diode D1 by-passes the lower half of the POT R3 during the charging cycle of the astable multivibrator. This is done in order to keep the output frequency constant irrespective of the duty cycle. Transistors Q1 and Q2 forms a darlington driver stage for the 12V lamp. Resistor R4 limits the base current of transistor Q1.</span></div> <div style="text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div style="text-align: justify;"> <b><span style="font-family: inherit;">Understanding the variable duty cycle astable multivibrator</span></b></div> <div style="text-align: justify;"> <span style="font-family: inherit;">As I have said earlier, the variable duty cycle astable multi vibrator based on NE555 forms the foundation of this circuit and a good knowledge on it is essential for designing projects like this. For the ease of explanation the timing side of the astable multivibrator is redrawn in the figure below.</span><br /> <span style="font-family: inherit;"><br /></span> <br /> <div class="separator" style="clear: both; text-align: center;"> <span style="font-family: inherit;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVPcKUHGrykCGFGvtTSrH432ltnCOhHyjR5V9ychMD__acX3YJ2RYe1V-cjQ07BntwS6i8Xmv8BXv8d_tKmG3cL7AttTeqx6kA4v09NmRI05Mym5kSm33NRoJGgN5FdpMwkFejogzPSMih/s1600/PWM+lamp+Dimmer2.png" /></span></div> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">Upper and lower halves of the POT R3 are denoted as Rx and Ry respectively. Consider the output of the astable multivibrator to be high at the starting instant. Now the capacitor C1 charges through the path R1, Rx, and R2. The lower half of POT R3 i.e. Ry is out of the scene because the diode D1 by-passes it. When the voltage across the capacitor reaches 2/3 Vcc, the internal upper comparator flips its output which makes the internal flip flop to toggle its output. As a result the output of the astable multivibrator goes low. In simple words, the output of the astable multivibrator remains high until the charge across C1 becomes equal to 2/3 Vcc and here it is according to the equation Ton = 0.67(R1+Rx+R2)C1.</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">Since the internal flip flop is set now, the capacitor starts discharging through the path R2, Ry into the discharge pin. When the voltage across the capacitor C1 becomes 1/3 Vcc, the lower comparator flips its output and this in turn makes the internal flip flop to toggle its output again. </span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">This makes the output of the astable multivibrator high. To be simple, the output of the astable multivibrator remains low until the voltage across the capacitor C1 becomes 1/3 Vcc and it is according to the equation Toff = 0.67(R2+Ry)C1. Have a look at the internal block diagram of NE555 timer shown below for better understanding.</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: center;"> <span style="font-family: inherit;"><img border="0" height="538" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiog_OulcrnI36K4Z10HstIuKrdbBrQB-y3vbbBXKeUYaTtOo51A06cmZg9Wi3qVvdmWOSUBaRd4m0J4aPb03oiAkEoNGmZ2Z6kr0fRUpmi4PttM2179AKSAt1dqf-xDqOgnJydmKcMFt78/s1600/PWM+lamp+Dimmer3.png" width="640" /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: center;"> </div> <div style="clear: both; text-align: justify;"> <b><span style="font-family: inherit;">How does the frequency remain constant irrespective of the position of POT3 knob?</span></b></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">What ever may be the position of  POT3 knob, the total resistance across it remains the same (50K here). If anything decreases in the upper side (Rx) the same amount will be increased in the lower (Ry) and the same thing gets applied to the higher(Ton) and lower(Toff) time periods. The derivation shown below will help you to grasp the matter easily.</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">With reference to Fig 2, we have:</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">Ton = 0.67(R1+Rx+R2)C1</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">Toff = 0.67(R2+Ry)C1</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">Total time period of the output waveform “T” is according to the equation :</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">T = Ton + Toff</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">Therefore, T = 0.67(R1+Rx+R2+R2+Ry)C1</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">           T= 0.67(R1+2R2+Rx+Ry)C1</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">We know that Rx + Ry  = R3</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">Therefore, T = 0.67(R1+2R2+R3)C1</span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">Therefore, frequency F = 1/(0.67(R1+2R2+R3)C1)</span><span style="font-family: Courier New, Courier, monospace;"> </span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;"><br /></span></div> <div class="separator" style="clear: both; text-align: justify;"> <span style="font-family: inherit;">From the above equation its is clear that the frequency depends only on the value of the components C1, R1, R2  and the over all value of R3 and it has nothing to do with the position of R3 knob.</span></div> </div>

PWM Lamp Dimmer

A simple and efficient PWM lamp dimmer using timer IC NE555 is discussed in this article. Earlier linear regulator based dimmers can onl...

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Rain Alarm Circuit

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> This is a simple <i><b>rain alarm circuit</b></i> that produces an audible alarm whenever rain falls. The rain detector circuit is based on two <i>transistors (Q1 & Q2)</i> and a <i>NE555IC (IC1)</i>. The two transistors are wired as a switch which goes on when the base of Q1 is shorted to the positive of the supply by the rainwater falling on the sensor. When the transistors are ON power supply is available to the IC1 which is wired as an astable multivibrator. The output of IC1 drives the speaker to produce an alarm.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Circuit Diagram</b></div> <div style="text-align: justify;"> <b><br /></b></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuoEP9PdGPuuQMdkXpOXko87zi88tNEUgTuXI0irGGlW2yJ-IcaIP9OFEtEcwut1aglQBKKOOWtqrQgEC-c8Vf34P0Q1a0RyzafaDZX4Yr9LO56cWjFtsEDGPn8mIKnNjYfyYX5I7Fj-zU/s1600/Rain+alarm+Circuit.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="471" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuoEP9PdGPuuQMdkXpOXko87zi88tNEUgTuXI0irGGlW2yJ-IcaIP9OFEtEcwut1aglQBKKOOWtqrQgEC-c8Vf34P0Q1a0RyzafaDZX4Yr9LO56cWjFtsEDGPn8mIKnNjYfyYX5I7Fj-zU/s1600/Rain+alarm+Circuit.png" width="640" /></a></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Notes</b></div> <div style="text-align: justify;"> <ol> <li>Assemble the circuit on a good quality PCB or common board.</li> <li>For assembling the sensor cut a 2×2 inch mica or plastic sheet. Arrange two single stranded wires (running parallel 2mm close to each other) on the sheet as shown in figure below. Remember the wires have to be non-insulated. Sensor ready.</li> <li>Now you can connect the points A&B on the sensor to corresponding points A&B on the circuit.</li> <li>POT R2 can be used to adjust the sensitivity.</li> <li>To test the circuit, make all connections and power up.Place a drop of water on the sensor so that two wires become shorted through water. Now the alarm starts sounding. If not adjust R2 to get the alarm sounding.</li> <li>Use a 9v battery or a 9V regulated DC supply for powering the circuit.</li> <li>Do not connect speakers less than8 Ohm impedance as load. It will damage the IC.</li> <li>A piezo buzzer can be also used instead of the speaker.</li> </ol> </div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Sensor Schematic</b></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtutdlUlE_iaXJKCgmYzBYTLqtli1QHJdNuUj1wKFyrjHGRtZe7Qg5cMf4TLXB_rbNkP2kl_lqS2f0L-I-7m0vFfjPfLgZkT8hr5wEBUFmkm5ITBAfZGWI19ahfz7IiW5-hkSWiVoiAHtO/s1600/RAIN+ALARM+CIRCUIT1.png" /></div> </div> <!-- Blogger automated replacement: "https://images-blogger-opensocial.googleusercontent.com/gadgets/proxy?url=http%3A%2F%2F3.bp.blogspot.com%2F-qkyPLMl-u3A%2FU4Q1mbtZUTI%2FAAAAAAAAARQ%2FEHCyE_j4orI%2Fs1600%2FRAIN%2BALARM%2BCIRCUIT1.png&container=blogger&gadget=a&rewriteMime=image%2F*" with "https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtutdlUlE_iaXJKCgmYzBYTLqtli1QHJdNuUj1wKFyrjHGRtZe7Qg5cMf4TLXB_rbNkP2kl_lqS2f0L-I-7m0vFfjPfLgZkT8hr5wEBUFmkm5ITBAfZGWI19ahfz7IiW5-hkSWiVoiAHtO/s1600/RAIN+ALARM+CIRCUIT1.png" -->

Rain Alarm Circuit

This is a simple rain alarm circuit that produces an audible alarm whenever rain falls. The rain detector circuit is based on two transis...

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Obstacle Avoiding Robot

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> This is a simple <i>obstacle avoiding robot</i> with two wheels that can be fabricated using a handful of generally available and inexpensive discrete components. The robot can perform avoidance manoeuvres whenever it detects an obstruction in its path. The electronic part is simple and can be built on a small piece of prototyping board. Although not terribly complicated, the mechanics do require a little care all the same. ROBBOT can be operate by a 6V (1.5x 4) battery pack.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Circuit Diagram</b></div> <div style="text-align: justify;"> <b><br /></b></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmGjLG1A4qEIr-OChVenmnx_oMtTVn6_spKwLAiBXWieKkFK4vAi-DCY3Q4PBf9cXYw3b4SLk_9R5NccJDxeyXZfSYz3FjwgVQG-fAsyOfI8ehKRdKbqSc33Cg-8v3s6qlzVtsl7m7obZV/s1600/Obstacle+Avoiding+Robot.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="322" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmGjLG1A4qEIr-OChVenmnx_oMtTVn6_spKwLAiBXWieKkFK4vAi-DCY3Q4PBf9cXYw3b4SLk_9R5NccJDxeyXZfSYz3FjwgVQG-fAsyOfI8ehKRdKbqSc33Cg-8v3s6qlzVtsl7m7obZV/s1600/Obstacle+Avoiding+Robot.png" width="640" /></a></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Working</b></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> ROBOT uses a front facing Infrared LED (Tx) to scan its path and a Photodiode (Rx) to detect light reverted from the obstacle by reflection. As soos as an obstruction is detected, ROBOT goes into reverse direction, and set off the locomotion in another forward direction. The sensor electronics is wired around the small <i>Op-Amp LM358N (IC1)</i>, which is an 8-pin chip having two inbuilt Op-Amps. One part of IC1 used here is configured in comparator mode. The sensitivity of the circuit is controlled by the reference voltage at pin 2 of IC1 using a 10K trimpot (P1). P1 will help to reduce unwanted detections caused by external light sources.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Parts list</b></div> <div style="text-align: justify;"> <b><br /></b></div> <table border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: none; mso-border-alt: solid windowtext .5pt; mso-border-insideh: .5pt solid windowtext; mso-border-insidev: .5pt solid windowtext; mso-padding-alt: 0in 5.4pt 0in 5.4pt;"> <tbody> <tr style="height: 22.0pt; mso-yfti-firstrow: yes; mso-yfti-irow: 0;"> <td style="border: solid windowtext 1.0pt; height: 22.0pt; mso-border-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <b><span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Symbol<o:p></o:p></span></b></div> </td> <td style="border-left: none; border: solid windowtext 1.0pt; height: 22.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <b><span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Name<o:p></o:p></span></b></div> </td> <td style="border-left: none; border: solid windowtext 1.0pt; height: 22.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <b><span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Value<o:p></o:p></span></b></div> </td> </tr> <tr style="height: 13.9pt; mso-yfti-irow: 1;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 13.9pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">IC1<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 13.9pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Op-Amp<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 13.9pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">LM358N<o:p></o:p></span></div> </td> </tr> <tr style="height: 10.75pt; mso-yfti-irow: 2;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 10.75pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">T1<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 10.75pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Transistor<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 10.75pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">BC547<o:p></o:p></span></div> </td> </tr> <tr style="height: 3.5pt; mso-yfti-irow: 3;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">D1, D2<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Diode<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">IN4007<o:p></o:p></span></div> </td> </tr> <tr style="height: 17.5pt; mso-yfti-irow: 4;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">LED1<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Green<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">5mm<o:p></o:p></span></div> </td> </tr> <tr style="height: 18.4pt; mso-yfti-irow: 5;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 18.4pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Tx<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 18.4pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Infrared LED<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 18.4pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">3mm<o:p></o:p></span></div> </td> </tr> <tr style="height: 16.6pt; mso-yfti-irow: 6;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 16.6pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Rx<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 16.6pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" style="margin-bottom: .0001pt; margin: 0in; text-align: center;"> Photodiode<o:p></o:p></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 16.6pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">3mm<o:p></o:p></span></div> </td> </tr> <tr style="height: 17.5pt; mso-yfti-irow: 7;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">RL1<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" style="margin-bottom: .0001pt; margin: 0in; text-align: center;"> DPDT Relay<o:p></o:p></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">6V<o:p></o:p></span></div> </td> </tr> <tr style="height: 3.5pt; mso-yfti-irow: 8;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">M1, M2<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">DC Motors<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <br /></div> </td> </tr> <tr style="height: 14.35pt; mso-yfti-irow: 9;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">S1<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">On/Off Switch<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <br /></div> </td> </tr> <tr style="height: 14.35pt; mso-yfti-irow: 10;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">R1<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Resistor<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">150 ohm<o:p></o:p></span></div> </td> </tr> <tr style="height: 14.35pt; mso-yfti-irow: 11;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">R2<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Resistor<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">10K<o:p></o:p></span></div> </td> </tr> <tr style="height: 14.35pt; mso-yfti-irow: 12;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">R3<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Resistor<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">120K<o:p></o:p></span></div> </td> </tr> <tr style="height: 14.35pt; mso-yfti-irow: 13;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">P1<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Potentiometer<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">10K<o:p></o:p></span></div> </td> </tr> <tr style="height: 14.35pt; mso-yfti-irow: 14;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">C1<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Capacitor<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">100uF/16V<o:p></o:p></span></div> </td> </tr> <tr style="height: 14.35pt; mso-yfti-irow: 15; mso-yfti-lastrow: yes;"> <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 59.4pt;" valign="top" width="79"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">C2<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 94.5pt;" valign="top" width="126"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">Capacitor<o:p></o:p></span></div> </td> <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.0in;" valign="top" width="96"><div align="center" class="MsoNormal" style="text-align: center;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%;">100nF<o:p></o:p></span></div> </td> </tr> </tbody></table> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Robot Parts</b></div> <div style="text-align: justify;"> </div> <ol> <li>Single Shaft Plastic Gear Motor x 2</li> <li>Plastic Wheel x 2</li> <li>Plastic Chassis Board</li> <li>Plastic Castor Bullet x 2</li> <li>DC Motor Clamp x 2</li> <li>4 x AA Battery Compartment/Holder x 1</li> </ol> <div style="text-align: justify;"> <b>Important Note</b></div> <div style="text-align: justify;"> Normally relay RL1 switches the positive and negative supplies to both motors M1 and M2. In case of an obstruction detection, RL1 switches to reverse the polarity of the motor connections. D2 now becomes reverse biased and hence supply to M2 is not available. Now only M1 goes into reverse mode. When RL1 switches back (no obstacle detection) Tiny BOT returns to the initial condition.</div> </div>

Obstacle Avoiding Robot

This is a simple obstacle avoiding robot with two wheels that can be fabricated using a handful of generally available and inexpensive di...

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Musical Bell Circuit

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> This circuits uses very few component and gives melody sound. It uses 3 terminal <b><i>IC UM66</i></b> and can be build small enough to be placed inside a greeting card and operated off a single 3V flat button cell.There is not much to the circuit. The UM66 is connected to its supply and its output fed to a transistor for amplification. Any common speaker can be used or a “flat” piezoelectric tweeter like the one found in alarm wrist watches. If you use the piezo, then it can be connected directly between the output pin 1 and ground pin 3 without the transistor.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The <b><i>UM66</i></b> looks like a <b><i>transistor</i></b> with 3 terminals. It is complete miniature tone generator with a tune. Now they come with wide variety of different tunes.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> For amplification we have used a NPN transistor which is BC548. Here BC548 makes a common emitter circuit. For limiting the base current we have used a resistance of 220 Ohms so that transistor will not get damaged by excess current.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <b>Circuit Diagram</b></div> <div style="text-align: justify;"> <b><br /></b></div> <div style="text-align: center;"> <img height="296" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFvL_Vy5OROUmjsfOWzDwWT0NnhuE3ZCzFfObnf52Z5Q1X3YoNymwBIEiaTL3u5a4BO4hdcObPIiviRk5Iv46XdDb9416YXj_K9KO4KjoBHmZBdino03qFwEpMtn6qb1L_idTng8XyQKZD/s1600/musical+bell+circuit.jpg" width="320" /></div> <div style="text-align: center;"> <br /></div> <div style="text-align: justify;"> <b>Important Points</b></div> <div style="text-align: justify;"> <ol> <li>Identify emitter base collector of transistor and pin no. of IC UM66.</li> <li>Make sure all points are well soldered according to the Circuit Diagram and no dry solders. Wrong connection of IC may heat up and get damage.</li> </ol> </div> </div> <!-- Blogger automated replacement: "https://images-blogger-opensocial.googleusercontent.com/gadgets/proxy?url=http%3A%2F%2F3.bp.blogspot.com%2F-4wni1OE9Kec%2FU6LEjSMqdHI%2FAAAAAAAAAZE%2FFzT3AGDGV3I%2Fs1600%2Fmusical%2Bbell%2Bcircuit.jpg&container=blogger&gadget=a&rewriteMime=image%2F*" with "https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFvL_Vy5OROUmjsfOWzDwWT0NnhuE3ZCzFfObnf52Z5Q1X3YoNymwBIEiaTL3u5a4BO4hdcObPIiviRk5Iv46XdDb9416YXj_K9KO4KjoBHmZBdino03qFwEpMtn6qb1L_idTng8XyQKZD/s1600/musical+bell+circuit.jpg" -->

Musical Bell Circuit

This circuits uses very few component and gives melody sound. It uses 3 terminal IC UM66 and can be build small enough to be placed insid...

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Multipurpose Circuit for Telephones

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> This add-on devices for telephones can be connected in parallel to the telephone instrument. The circuit provides audio-visual indication of on-hook, off-hook, and ringing modes. It can also be used to connect the telephone to a <b>CID</b> (<b>caller identification device</b>) through a relay and also to indicate tapping or misuse of telephone lines by sounding a buzzer.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> In on-hook mode, 48V DC supply is maintained across the telephone lines. In this case, the bi-colour LED glows in green, indicating the idle state of the telephone. The value of resistor R1 can be changed somewhat to adjust the LED glow, with-out loading the telephone line (by trial and error).</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> In In on-hook mode of the handset, potentiometer VR1 is so adjusted that base of T1 <b>BC547</b> is forward biased, which, in turn, cuts off transistor T2 <b>BC108</b>. While adjusting potentiometer VR1, ensure that the LED glows only in and not in red.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> When the handset is lifted, the voltage drops to around 12V DC. When this happens, the voltage across transistor T1's base-emitter junction falls below its conduction level to cut it off. As a result transistor pair T2-T3 starts oscillating and piezo-buzzer starts beeping (with switch S1 in on position). At the same time, the bi-colour LED glows in red.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> In ringing mode, the bi-colour LED flashes in green in synchronisation with the telephone ring.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> A CID can be connected using a relay. The relay diver transistor can be connected via point A as shown in the circuit. To use the circuit for warning against misuse, switch S1 can be left in on position to activate the peizo-buzzer when anyone tries to tap the telephone line. (When the telephone line is tapped, it's like the off-hook mode of the telephone handset.)<br /> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirha3F9d72JD6L8NPr-1sPS3_Iub1KJBJ4l6Wso7ZQQ5GeZo_v2_U1cheGv9AFLzL1AEcuSfLv8oQSTF7jA7C8o3TUsqDZOJnSJXqUUomAPsZzaKw1bo-F__GQqrk4gpggomnQdSWYsRVh/s1600/Multipurpose+Circuit+for+Telephones.JPG" imageanchor="1"><img border="0" height="375" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirha3F9d72JD6L8NPr-1sPS3_Iub1KJBJ4l6Wso7ZQQ5GeZo_v2_U1cheGv9AFLzL1AEcuSfLv8oQSTF7jA7C8o3TUsqDZOJnSJXqUUomAPsZzaKw1bo-F__GQqrk4gpggomnQdSWYsRVh/s1600/Multipurpose+Circuit+for+Telephones.JPG" width="640" /></a></div> <div style="text-align: justify;"> <br /> Two 1.5 volt pencil cells can provide Vcc1 power supply, while a separate power supply for Vcc2 is recommended to avoid draining the battery. However, a single 6-volt supply source can be used in conjunction with a 3.3 volt <b>zener diode</b> to cater to both Vcc2 and Vcc1 supplies.</div> </div>

Multipurpose Circuit for Telephones

This add-on devices for telephones can be connected in parallel to the telephone instrument. The circuit provides audio-visual indication ...

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