Wireless Audio Transmitter

About: Simplicity is the ultimate sophistication..!!

Hey world...

This is a instructable on wireless audio transmitter.In most of our day to day life we come across situation where we need a connect our iPod,mobile,laptop.....etc. to our sound system,but the major limitation is the cable that we need to connect.This probably happens if your sound system doesn't have a wireless connectivity option.i too had the same problem so i decided yo solve it...:-)
Basically its a adjustable FM transmitter that is designed to transmit sound waves to the radio receiver.We connect the transmitter to our device and use a old phone or FM receiver to connect to our sound system.This might seem odd as we are kinda broadcasting our-self but the range of the transmitter is limited to 800 meters only.The reason choosing this option is that it is very very CHEAP ..!!Also u can connect multiple sound systems at a time without any worries of sync.Hope this project helps you.!

Step 1: Electronics You Need

Parts List :

Resistors :

R1 - 10k

R2 - 15k

R3,R4 - 4k7

R5 - 68E(68 ohms)

R6 - 2k2

R7 - 10E(10 ohms)

Capacitors :

C1 - 2.2uF/25v

C2,C3 - 10KpF(103)

C4,C5 - 10pF

C6,C7 - 1KpF(102)

Transistors :

Q1 - BC548

Q2 - C2570

Inductors (air core):

L1 - 4 turns (22 S.W.G Copper wire)

L2 - 4 turns (22 S.W.G Copper wire)

L3 - 6 turns (22 S.W.G Copper wire)


Trimmers 1,2,3 - 22pf

Antenna - 30 cm

MIC (optional) - condenser MIC

Audio Jacks:

3.5 mm mono jack

3.5 mm female jack

6.5 mm mono jack (guitar jacks)

6.5 mm female jack

Step 2: Tools You Need

Tools :

Soldering iron

Soldering wire



Wire stripper



De-soldering pump

PCB hand drill (if needed)

Step 3: Schematics for the Transmitter

The above Image shows the transmitter Schematics you'll need to make the PCB.I have used a black zero PCB i.e. one that is used make a new prototype ;-).In the schematic instead of the MIC you can use a Mono jack. The pinouts for the jack are given above.Its has only two pins GND and Signal.The antenna can be replaced with a simple wire

Step 4: After Building the Transmitter

You should get this after building the PCB. I've used a plastic box to place the circuit.The transmitter has a 2 basically a 2 stage transmitter having a V.H.F. oscillator and a R.F. power amplifier.R.F. output power is 100 milliwats. Frequency of the Transmitter can be set with in 88- 108 MHz band by adjusting the first trimmer and also by adjusting the distance between the coil.Adjust the other 2 trimmers for max radiation.Connect a 9 volt battery and thats about it..!

Step 5: Applications

I had small speakers which I've connected to the speakers as radio receiver we can even use a FM receiver too. The tab is connected to the transmitter . So now whatever the tabs audio output is, it is being broadcast and received by the receivers.Also if you have to many transmitter in the at one place just change the frequency of the transmitter.
Here's a video of that.You can connect multiple sound systems now, by just getting a new receiver to each sound system.

Step 6: Its Done..!!

Your done and hope fully the R.J. of your area .. ready to rock your neighbors..!!



    • Warm and Fuzzy Contest

      Warm and Fuzzy Contest
    • Sweet Treats Challenge

      Sweet Treats Challenge
    • Faux-Real Contest

      Faux-Real Contest

    21 Discussions


    Question 4 months ago on Step 3

    Hi, could you explain how the transmitter works, please? Why did you build it like that and why does it need so many capacitors and so on. Would be very interesting :D


    1 year ago

    is it working for tv?


    2 years ago

    Can you give a vedeo how to make or written method please !! In this page or on my watsapp number please!!.-9122219711


    Reply 4 years ago on Introduction

    Thats a good one .. but i think i have a solution....
    for my solution you'll be needing two such transmitter's and two receiver's with some modification..
    the idea is that ..in mono we send a single signal to the receiver but in case of stereo we need two outputs (the device generates two signals) to be sent...so we'll send those signals on two different carriers and receive them at two different receivers(on different frequencies) and connect them to one jack to get a stereo output.See in the image you'll see the stereo jacks have left and right signals ..


    Reply 2 years ago

    The image is incorrect, a 3 conductor jack does not contain a mic. it only has ground, left and right audio so the tip of the left jack is also audio out. The right jack is correct.


    Reply 4 years ago

    thanks bro!!
    I have bought all the parts. and going to make it but i need help so can i get ur fb id or whatsapp no so that i can contact you for help in realtime.

    my whatsapp no- 8126648064


    3 years ago

    I can't find a place to buy that C2570 and I know to little to find something simmillar that I can use. I can't find the ones that Scifiswapnil posted neither :-/

    3 replies

    Reply 3 years ago

    Yay! At least I found that one on Ebay. Looks like the usual big german electronic retailers are not too familliar with your choice of transistors :)


    Reply 3 years ago

    Oh looks like the big retailers got them too, it's just that their site-search-tool sucks :)


    3 years ago

    Is this type of circuit legal to operate? What is the range?


    3 years ago

    I did everything what was in the above steps.. But mine is not working.. The output is not coming

    1 reply

    Reply 3 years ago

    did you tried changing the pot values, try doing this:

    1) set a radio receiver to a fixed channel

    2) now change the pot of the transmitter till you hear the sound on the receiver


    4 years ago

    im not getting c2570 transistor so is there any replacement for that which i can use Atty it's place

    1 reply

    4 years ago

    is it a mono or stereo transmitter???