This circuit was proposed by an old American documentation for listening to SSB stations. The circuit makes use of a small old radio 455 kHz IF transformer.
This small crystal microphone transmitter was indicated in an 80s spy book. The range depends on...
The figure shows how to use an operational amplifier with a low impedance head. The gain is...
Voltage comparators, such as those in the LM139/239/339 series, consist of devices that can be...