This circuit uses a resonant reed switch at the trigger frequency. The circuit is from General Electric in a 1966 documentation. This type of component is rare today.
Any JFET can be used in this circuit suggested by Electronics Now magazine, April 1993. The...
This circuit allows you to view two low frequency signals on a single channel oscilloscope. It was...
Found in an old Popular Electronics this circuit is still current. The SCR can be of the 106...