This circuit was obtained in a 1970 engineering documentation. The operational is the 741, but other operational ones can be used. The power supply must be symmetrical.
The circuit shown is from a 1975 Motorola thyristor manual. The triac can be of the TIC series and the...
This crystal tester was found on a 90s Ham Radio. Transistors are commonly used. The circuit is for...
This circuit was found in Radio Electronics magazine from April 1960. It was in an article that...