Amplitude Modulation AM with Op Amps

298

02:39:59

Inject noise to start carrier oscillator. Carrier wave is passed through a CMOS inverter. The signal wave is shifted up and inverted. This splits the signal into a differential pair of waveforms with one waveform shifted up and the other shifted down and 180 degrees out of phase. The up-shifted waveform is used to clamp the high rail of the CMOS inverter and the down-shifted waveform clamps the low rail. The resultant output is the carrier wave with an amplitude modulated by the signal wave.

published 2 years ago

joshinator

2 years ago

I tested this circuit IRL with an extra cmos inverter and 1nF caps at the op amp outputs and it worked very well at transmitting over antenna at AM frequencies! UA741CN general purpose amps used. And the oscillator needs to be appropriately biased. Fidelity could probably be increased by tweaking values. But I hooked up an audio jack and was able to play audio and distinguish different components and voices in the signal. Give it a go and let me know what you think!

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