What sets this transmitter apart, which we found in a 1990 documentation, is the modulation by the emitter of the transistor. This type of modulation allows the use of low impedance microphones, with changes in R4. The coil has 4 turns of AWG wire 26 or 28 in a 1 cm long form without core and the supply with higher voltage takes the transmitter to a good range (more than 500 meters).
