This static switch circuit appears elsewhere on this site from other sources. This was obtained from a Motorola documentation for 1968 power circuits. The Triac can be another according to the load.
This circuit accelerates the tripping of a relay when energized. The circuit uses the CA3018...
The circuit shown is from the National Semiconductor 1994 Linear Applications Handbook. The base...
This ultra-simple circuit has the frequency determined by the LC network. Any general purpose JFET...