Walky-Talky

Walky-Talky in this website is world 1st verified walky-talky project without using coil. Walky talky is very interesting and attain grabbing project for electronics hobbyist. Communication is done without any physical connection and mobile network up range of 500 meter. Almost all communication devices utilize coil which is burden for electronics hobbyist. So, we design this circuit without using any coil.

Circuit Descriptions of Walky-Talky

The entire circuit of walky-talky is divided into two main section transmitter and receiver section.

Transmitter section : Transmitter section utilize IC NE566 (IC4) as VCO (Voltage Control Oscillator) for generating frequency about 30 KHz. Resistor R24 with Capacitor C24 used as frequency components for frequencies determination. Voice is pick-up by mike (MIC1) and changed it into equivalent electrical signal. Signal from microphone is amplified by transistor T4 and given to pin no 5 0f IC4. NAND gate N1 with crystal oscillator XT4 finalizes the output from pin 3 of IC3. Lastly, signal from NAND N2 through N3 and N4 given to antenna for transmission.

Receiver section : Transmitted signal from another walky-talky is received from same antenna which is used for transmission. Field effect transistor T1 boosts the received signal and make more powerful and send to amplifier section made from transistor T2 and T3 with crystal oscillator XT1 through XT3. Detector section is made from diode D1, Capacitor C6 and resistor R12. 30 KHz frequency is obtained from detector section.

Frequency of Phase Locked Loop IC NE565 (IC1) is adjusted by capacitor C9, resistor R17 and variable resistor VR1. Amplifier IC LM386 (IC2) is used to amplify the signal and given to speaker.

Circuit Diagram

Parts List

• Resistors (all ¼-watt, ± 5% Carbon)

1. R1 = 47 KΩ
2. R2 = 100 Ω
3. R3, R4, R11, R27 = 2.2 KΩ
4. R5 = 330 KΩ
5. R6, R10 = 560 Ω
6. R7 = 1 KΩ
7. R8 = 220 KΩ
8. R9 = 100 Ω
9. R12, R15, R16 = 4.7 KΩ
10. R13, R31 = 10 KΩ
11. R14 = 15 KΩ
12. R17 = 1.8 KΩ
13. R18 = 1.2 KΩ
14. R19 = 1 KΩ
15. R20 = 4.7 Ω
16. R21, R22 = 100 KΩ
17. R23 = 120 KΩ
18. R24 = 5.6 KΩ
19. R25 = 22 KΩ
20. R26 = 150 KΩ
21. R28 = 330 Ω
22. R29 = 220 KΩ
23. R30 = 47 KΩ
24. VR1 = 4.7 KΩ
25. VR2 = 22 KΩ

• Capacitors

1. C1, C6, C10, C24 = 1 KpF
2. C2, C4, C5 = 47 KpF
3. C3 = 20 KpF
4. C7, C9, C23= 2.2 KpF
5. C8 = 4.7 µF/16V
6. C11 = 22 KpF
7. C12, C16 = 0.1 µF
8. C13 = 2.2 µF/16 V
9. C14, C19, C25, C26 = 0.22 µF
10. C15 = 10 µF/16V
11. C17 = 220 µF/16V
12. C18, C20 = 10 KpF
13. C21, C22 = 68 pF
14. C27 = 1000 µF/16V
15. C28 = 10 µF/16V

• Semiconductors

1. IC1 = NE565 (Phase Lock IC)
2. IC2 = LM386 (Amplifier IC)
3. IC3 = CD4011 (Quad 2-input NAND Gate IC)
4. IC4 = LM566 (Voltage Controlled Oscillator)
5. IC5 = LM7812 (Voltage Regulator)
6. T1 = BFW10
7. T2, T3 = BF194
8. T4 = BC148
9. D1 = 1N4148

• Miscellaneous

1. XT1 – XT4 = 10.7 MHz crystal
2. SW1 = Single pole double throw switch
3. LS1 = 8Ω speaker
4. MIC1 = Condenser microphone
5. Areal