- on RF (radio)
- Published in issue 7/2002 on page 0
AM Demodulator for Intercom
This circuit should be considered as more of an experimental circuit for AM demodulation, than as a practical application. In the associated ‘AM modulator’ we have raised the problems caused by mains hum, getting in the way of interference-free operation of the AM mains intercom. When the transmitter and receiver are not coupled through the mains then the quality is perfectly adequate.The ‘receiver’ used here is the same as found in the ‘mains remote switch’ and ‘mains remote control decoder’ (C1 to C5/TR1/L1). The capacitor that connects the small toroidal transformer to the mains has been split into two, making the circuit a little bit safer. But please note: the complete circuit should be considered as being at mains potential. So don’t solder to the circuit or take any measurements while it is switched on.