AM Transmitter

Here we introduce an AM transmitter circuit, which has stable frequency, simple circuit, easy production and can be successfully used without debugging. It can be used for radio debugging and dial calibration, etc.

The transmitter circuit uses a CD4049 inverter, which makes the circuit very simple. The circuit uses inverter III as the RF oscillator, and the frequency of the RF oscillator is controlled by a 1MHz crystal. Inverters IV and V form an amplification and shaping circuit to improve the effect. Inverters I and II and the peripheral R1, R2, and C1 form an audio oscillator to modulate the RF signal. The antenna can use a few inches of wire.

The frequency of the transmitter can be changed by simply changing the oscillation frequency of the crystal oscillator (the frequency of the crystal oscillator can be 2MHz, 3MHz, etc., and the maximum can be 10MHz). Therefore, as long as a suitable crystal oscillator is replaced, the circuit can also verify the SW frequency band of the radio.