This circuit, from a 303 Circuits from the 90s, uses a telephone pickup coil as a sensor to capture power grid noise, thus making it possible to locate electrical wiring.
This circuit has an automatic dynamic gain control in a range of 6 dB to 40 dB. We found it in...
This circuit doubles the frequency of a signal using a varicap. In this case, the input is 28 MHz,...
The presented circuit was found in the National Semiconductor FET Databook. The setting applies to other...