The circuit is from the 1994 National Semiconductor Linear Applications Handbook but can be implemented with more modern operational amplifiers. The power supply must be symmetrical.
Found in a Popular Electronics from the 80's, this circuit triggers an SCR keeping an LED on when...
Found elsewhere in this section, this circuit is from the April 1971 Radio Electronics magazine. Note...
This circuit works with practically any tunnel diode, transmitting signals in the FM range with a...