This circuit is from an1966 General Electric documentation. The Triac can be equivalent to 6 A or more, mounted on a good heatsink. Any diac can be used.
This circuit, found in documentation from the 1980s, uses an operational amplifier from that time....
This low frequency sinusoidal oscillator was obtained in documentation from the 1970s. Operational...
This circuit was found in a 1980s documentation. It is intended for remote vibration monitoring...