Simple AM Transmitter

There are not many AM
transmitters that are easier to build than this one because the inductor
is not tapped and has a single winding. There is no need to wind the
inductor as it is a readily available RF choke (eg, Jaycar Cat LF-1536).
To make the circuit as small as possible, the conventional tuning
capacitor has been dispensed with and fixed 220pF capacitors used
instead. To tune it to a particular frequency, reduce one or both of the
220pF capacitors to raise the frequency or add capacitance in parallel
to lower the frequency. Q1 is biased with a 1MO resistor to give a high
input impedance and this allows the use of a crystal ear piece as a low
cost microphone.

Simple AM Transmitter Circuit

Simple AM Transmitter Circuit Diagram

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