The circuit is identical to the V7 VHF FM Transmitter but with a few small additions. TR1 (BC547) is an inverted Hartley oscillator which based upon an inductor fabricated on the PCB. This makes it megga-stable, and setable anywhere in the VHF FM band (76MHz to 119MHz) and the BB105 varicap makes it voltage tuneable [...]
A truly minimalist circuit. Performance is relatively poor and stability is a problem. Q1 modulates the signal and acts as an oscillator. L1 and C5 determine the frequency. Decrease C5 for a higher frequency and vice-versa.
You won’t get a long range transmission with this one. The author claims 50-500 feet. A lot depends on the [...]
While there are a plethora of similar 2-transistor schematics available, this one is above average. A major improvement over the little 1-transistor circuit that we’ve discussed previously, this transmitter consist of two stages. The first transistor is used to amplify audio, which means that the microphone is now much more sensitive to sound. The second [...]
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