This telephone circuit was found on a 90's EDN. It keeps a flashing LED to indicate that there was a call in your absence. The components admit equivalents.
The trigger element of this circuit is a neon lamp. The SCR admits an equivalent. We found it in...
This bistable with transconductance operational amplifier was found in early National...
This 1965 circuit consists of a small inverter for an ultraviolet lamp. The circuit is from a...