Saturday, April 16, 2011

1 km. FM Transmitter


This one is a high power long range (use yagi antenna)  FM Transmitter  that provides very good frequency stability in about 1km range and very good microphone sensitivity. It can be used inside guitars, as a part of remote control systems or in other similar applications.

The features said above are achieved by including an RF amplifier stage with 10dB gain and AF preamplifier stage to boost the modulation.

The circuit construction is simple. L1 is integrated into the PCB with 3.25 turns. Transistors are not critical. The BC547s can be replaced with any small signal NPN type transistor and BC557 is a general purpose PNP transistor so it can also be replaced easily.

The power consumption is low. The finished circuit draws about 30mA. A single 9V battery is ample to power the FM wireless microphone.

The PCB file is given in the download section of the project page. You should check Harry's page for more detailed information about the components, PCB modifications and the other features of the circuit.

if you need more details then post a comment below

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