It’s been tested and reported to work very well. This simple FM transmitter is very powerful (not a simple transmitter, but easy to build). Using this transmitter, you can transmit FM signals up to a circular area with a radius of 5 km. A 12V battery is recommended to power the circuit.
A ready-made 12V AC-DC adapter can be used, but if a low-frequency hum is very disturbing while listening to the FM radio output, you should use a power supply with a regulated, clean DC output from a classic sheet metal transformer.
For the antenna, use the center wire of a 75Ω TV cable, which gives the best results. It should be at least 2 meters long. If you can’t find antenna cable, you can use any copper wire.
Note: You don’t need to strip the entire TV cable and remove the center wire; just make sure the ground wire wrapped around it doesn’t touch the center wire.
To make the L1 coil, use 18 SWG copper wire (approximately 1 mm in diameter) and wrap it 7 times with a diameter of 1 cm.
NOTE: A warning has been issued regarding the use of a heatsink for the transistor. Otherwise, it is stated that the transistor will be damaged within a few minutes. Also, powering the circuit before connecting the antenna may damage the transistor.
Long Range Powerful FM Transmitter Circuit Diagram
PCB Drawing of a Powerful Long-Range FM Transmitter
Note: PCB design was created using Sprint Layout 6. It has been checked but not tested. PCB dimensions are 62x72mm.
Warning: This project is for educational purposes only. If you wish to use this circuit, you must obtain permission from the relevant authorities.
