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Walky-talky without using inductor or coil

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.

PARTS LIST

Resistors (all ¼-watt, ± 5% Carbon)

R1 = 47 KΩ

R2 = 100 Ω

R3, R4, R11, R27 = 2.2 KΩ

R5 = 330 KΩ

R6, R10 = 560 Ω

R7 = 1 KΩ

R8 = 220 KΩ

R9 = 100 Ω

R12, R15, R16 = 4.7 KΩ

R13, R31 = 10 KΩ

R14 = 15 KΩ

R17 = 1.8 KΩ

R18 = 1.2 KΩ

R19 = 1 KΩ

R20 = 4.7 Ω

R21, R22 = 100 KΩ

R23 = 120 KΩ

R24 = 5.6 KΩ

R25 = 22 KΩ

R26 = 150 KΩ

R28 = 330 Ω

R29 = 220 KΩ

R30 = 47 KΩ

VR1 = 4.7 KΩ

VR2 = 22 KΩ

Capacitors

C1, C6, C10, C24 = 1 KpF

C2, C4, C5 = 47 KpF

C3 = 20 KpF

C7, C9, C23= 2.2 KpF

C8 = 4.7 µF/16V

C11 = 22 KpF

C12, C16 = 0.1 µF

C13 = 2.2 µF/16 V

C14, C19, C25, C26 = 0.22 µF

C15 = 10 µF/16V

C17 = 220 µF/16V

C18, C20 = 10 KpF

C21, C22 = 68 pF

C27 = 1000 µF/16V

C28 = 10 µF/16V

Semiconductors

IC1 = NE565 (Phase Lock IC)

IC2 = LM386 (Amplifier IC)

IC3 = CD4011 (Quad 2-input NAND Gate IC)

IC4 = LM566 (Voltage Controlled Oscillator)

IC5 = LM7812 (Voltage Regulator)

T1 = BFW10

T2, T3 = BF194

T4 = BC148

D1 = 1N4148

Miscellaneous

XT1 – XT4 = 10.7 MHz crystal

SW1 = Single pole double throw switch

LS1 = 8Ω speaker

MIC1 = Condenser microphone

Areal

 

 

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62 thoughts on “Walky-talky without using inductor or coil”

  5. Hi ..
    It’s interesting circuits but I’m wondering about the interference effect to public FM radio receiver, since it’s use 10,7 Mhz Frequency carrier ..
    Is there any info regarding this ?

    BR//Tatang

    Reply

    1. Here we are using the Intermediate frequency band with frequency 10.7 Mhz for transmission and the public FM in most countries uses VHF band for FM broadcasting , So it should not be a problem in most countries.
      The Frequency is also used by some Satellite and FM broadcasters in some few places ( Which I haven’t heard of till now) .
      But I suggest to make sure that the frequency 10.7 mhz is not used by any other broadcaster in your place before building this project.

      Reply

  10. 1. What is the aerial antenna and what are its specifications for buying it so that it can be used in the above circuit??
    2. Is it possible in this circuit to transmit or receive the signal at a time???
    3. can you elaborate the working of the complete design circuit (not the working of vco, amplifier, etc.but the working of what mode in which it receive or in what mode it transmit)?????????

    Thanks

    Reply

  14. Hi sir,this is excellent.i’m not an electronic student but i am interested in doing these projects.Is there any chance in increasing range.

    Reply

  33. Sir Plz do reply, I have few questions !!
    1) My NE566 IC heated up like a burning coal whenever i applied the voltage, i have checked every single connection, i have done the connections exactly instructed in the circuit, so whats the problem? Is it normal?
    2) Any equivalent of BFW10? in my area there is no BFW10 available so i am using BC246A. Is it correct? Because BC246A is also N-channel JFET, can U recommend any equivalent??
    3) Can i use 11.0592Mhz crystal instead of 10.7Mhz ???
    Please sir do reply urgently, I have to submit this project within a week.
    Thanks in advance

    Reply

  36. Is there 10,7MHz crystal or ceramic filter? As i know 10,7MHz is a ceramic filter (CF). Or maybe i dont know if 10,7MHz is crystal too. And how about pin number if that is a ceramic filter (CF)?

    Reply

  38. Sir, can i connect an audio signal direct to the mic input point after removing the mic.
    hope 500 mtrs range will not violate the fcc rules,is the transmission free from disturbances,is a thin shield
    metal cover grounded to the negative supply required for any section to avoid noise and disturbances,what is the min and max current drawn by the circuit when the system is on ideal cond and current during transmission /receiving . Regards Sambath kumar.

    Reply

  47. How is that you build these circuits? I mean like how yo know where to play e the resistor and the values of the resistor , though I know that its done by calculation how to actually build these complex circuits on my known. I am sure my questions is difficult to answer or could nor be explained in a comment so please at least direct me to the materials that can help me develop these skills of building and designing circuits on my own. Your help would be appreciated and beneficial. Please reply me positive. Thank you very much.

    Reply

  49. I am a novice in electronics. Well concerning the circuit it contains an oscillator with three pins can a two pin oscillator also be used.

    Reply

  50. Hi,

    I am struggling to find the transistors – T1 = BFW10; T2, T3 = BF194; T4 = BC148. Could you please suggest any other models that wiould replace these. Thanks in advance.

    Reply

  51. I am struggling to find these T1 = BFW10; T2, T3 = BF194: T4 = BC148 transistors. Any suggestions that could replace them. Thanks.

    Reply

  54. Hello Sir, can you please message me regarding the antenna? What is it actually? and what type of modulation is used in this circuit? Is it guaranteed that this scheatic works? Thank you for the response, hope can have it sooner 🙂

    Reply

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