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FM Transmitter
About the device in general
The transmitter can operate in wavelength 88-108 Mhz.
This is a radio frequency, which can be picked up by any radio receiver.
It is designed for monitoring small rooms and closed areas and has a sensitive microphone connected on the input.
The circuit
This prototype is based on an extremely simple circuit. The hart of it is logic 7413.
Adding three more elements and you have the transmitter ready.
The transmission distance is between 10-30 meters with antenna 30 cm and 4.5V supply.
The size of the device presented on the picture is 3x1.5 cm without the antenna (blue rounded wire).
The device can easily be fit into a box of Tic-tac sweats together with 2 batteries for supply.
It requires only moving the microphone in the place of the antenna. The sensitivity of the device is very
high considering the complexity of the circuit. You can sense even ticking of the clock in the room.
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