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Description 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. Description 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 modi...

Amplifiers which run from 12V DC generally don’t put out much power and they are usually not hifi as well. But this little stereo amplifier ticks the power and low distortion boxes. With a 14.4V supply, it will deliver 20 watts per channel into 4-ohm loads at clipping while harmonic distortion at lower power levels is typically less than 0.03%. This is an ideal project for anyone wanting a compact stereo amplifier that can run from a 12V battery. It could be just the ticket for buskers who want a small but gutsy amplifier which will run from an SLA battery or it could used anywhere that 12V DC is available – in cars, recreational vehicles, remote houses with 12V DC power or where ever. 20W Stereo Audio Amplifier Because it runs from DC, it will be an ideal beginner’s or schoolie’s project, with no 240VAC power supply to worry about. You can run it from a 12V battery or a DC plugpack. But while it may be compact and simple to build, there is no need to apologise for “just average” pe...