This circuit was published in a 90s Radio Electronics. The circuit uses the well-known LM386 that appears in a large number of projects on this site.
We found this circuit in a 1967 RCA SCR manual. The circuit uses components from the era. The...
A simple bistable configuration can be obtained based on just one amplifier, as shown in the...
This series sensor circuit is from 1995 Popular Electronics. The circuit can use any SCR and the...