This circuit for audio signals was found in the March 1990 Radio Electronics magazine. The circuit uses a unusual optocoupler that can be replaced with an equivalent one.
This is the simulation of a Ultrasound Receiver using the 741 IC, an operational amplifier....
The resonant circuit depends on the crystal frequency that can go up to a few megahertz. The...
With this circuit it is possible to select the upper or lower side band on an SSB transmission by...