Friday, July 4, 2014

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 Diagram

Simple AM Transmitter Circuit Diagram

1 comment:

  1. Hello, Magnificent Information.

    I need a low power AM transmitter (200mW) for 27.1 MHz.

    Modulation frequencies are from 100 Hz to 100 KHz.

    My e-mail is:

    Thanks for your help.