This circuit was found in Raytheon's 1967 documentation. The circuit uses an operating of the era, but the configuration can be applied to modern operational amplifiers.
The purpose of this circuit is to adapt a common speaker to function as a microphone. The circuit is...
This amplifier circuit for listening was found in a book by Hugo Gernsback from 1960. The...
The presented circuit uses an optocoupler to trigger a triac. We found it in a Popular Electronics from...