This simple circuit to monitor the frequency of the power grid uses an analog indicator. The adjustment trimpot can be 4k7 and the indicator is 100 mA full scale.
This boost amplifier was found in a Popular Electroniics from the 90s. The circuit operates up to...
This simple transistorized radio for listening on a crystal phone was found in a Japanese...
The circuit presented, from 2006, serves to control loads at a distance, robots, etc. It can be...