A modulated transmitter with variable tuning. The modulation is applied to the base and varies the frequency of the
tank circuit, thereby producing FM modulation. However there is enough cross distortion that the signal is also
received by AM radios. The antenna circuit is tuned and transmits using a long wire antenna.
Please Note. It is illegal to transmit on the broadcast bands in most countries, as such this circuit is shown for
educational purposes only.
Please read the disclaimer
on this site before making any transmitter circuit. It is
illegal to operate a radio transmitter without a license in most countries. This circuit is deliberately limited in output
power but although strictly FM provides enough cross modulation to be received on amplitude modulation (AM) . The ooutput
radio frequency is in the range 500kHz to 1600kHz with values shown.
You can apply differemt input values in the calculator below, remember to change drop down box to picofarads for
capacitance and microhenries for the coil. The coil is fixed at 200uH, the capacitor values can be varied and resonant
by using the calculator below.
Tuned Circuit Resonant Frequency Calculator