This FM Wireless Microphone project has good frequency stability and has range over 1 Km (under good conditions). This project features RF amplifier buffer (10dB gain), an AF preamplifier to boost the modulation and good microphone sensitivity. You can use it for guitars and remote control system.
This project quite simple to build. The two BC547 transistors can be replaced with any small-signal NPN transistor, such as the 2N2222. L1 is 3.25 turns in spiral form and is an integral part of the PCB foil pattern. The final stage is a BC557 PNP general purpose device. If you use different devices then you should select the 1M0 resistor for 5-volts DC at the collector of the first transistor. Select the 47K resistor for 3 – 4 volts on the collector of the third transistor.
© Harry Lythall
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