Micro FM Radio Transmitter
As you already know, the fm radio transmitter may be used for many purposes like transmitting your pirate radio signals(also known as ‘ghost signals’ or ‘ghost waves’) throughout the air or for spying (eg.listening to one’s speech secretly). etc, but it’s illegal and maybe put you in prison for a long time! So i request you to not use this device against any person or for any kind of illegal activities, also building and using radio transmitters without a license is illegal in most countries because these unstable frequencies may confuse with fire,ambulance,police,aircraft frequencies. so use this circuit at your own risk! Moreover i don’t recommend you to build this transmitter and if you used this device for some good purposes, such as ‘transmitting music in your college or just to your backyard’ then i recommend you to use it but never use a long antenna to get more range as it may jam the “life” frequencies
This circuit requires SMD components to make it as small as possible, so you need to get some SMD components such as smd resistors,smdcapacitors..etc you may get all these from junk(eg.damaged circuit boards, but you must test them before soldering to the pcb) circuit boards if it’s not easy to get from electronics components selling stores. You may need micro soldering iron although i used an ordinary one to get it all soldered, but it was quite hard to solder the SMD components onto the PCB using an ordinary soldering iron.
The picture below shows some SMD resistors and how to calculate their values
SMD resistor table
Here is the circuit diagram of micro FM TRANSMITTER, just change every components in the circuit to SMD except the Transistor,coil, and two 15pf and 5pf ceramic capacitors. A tuning cap (variable capacitor) is not needed in the circuit, because you can replace it with a ’15pf’ ceramic capacitor, but if you want change the frequency of your transmitter, then gently spread the ‘spacing’ between the turns of coils.
COMPONENTS YOU NEED
T1 – s8050 NPN transistor
VC1 – use a ’15pf’ ceramic capacitor (not SMD)
L1 – coil, get a pen refill(must be 3mm diameter) and a short length(1mm thick) copper wire,wind exactly ‘6 turns’ over the refill and scrap its both ends with a blade. Done!
C3 – 5pf ceramic capacitor (printed exactly ‘5’ on it)
C4 – ceramic capacitor ‘104’ (printed just ‘104’)
C1 – use an SMD one (just an smd capacitor)
C2 – 22n Ceramic
R1 – 47k SMD resistor (printed ‘473’)
R2 – 100 ohm (printed ‘101’)
ANT – a short length wire
3V ~ 9V supply (use only battery)
Note: a mic may be added in the circuit to transmit your voice, but you have to modify the circuit for this purpose!