SCR Rain or Leak Alarm (CB22097E)

This sensitive circuit was found in old documentation. The SCR can be any of the 106 series and the transistor a BC548.

Missing pulse detector (CB7547E)
Using a 555, this configuration appears elsewhere on this site. This is from American...
Operational Half Wave Rectifier (CB19494E)
This precision half-wave rectifier circuit using an operational amplifier was found in a 1980s...
Girator III (CB18896E)
This spinner (see CB18894E) uses only an operational amplifier that must be powered by a...