This circuit was found in the Electronics Experimenter Handbook from 1991. The circuit controls a simple relay for the purpose of turning circuits on or off or switching audio channels.
We found this circuit in a Popular Electronics of the 90s. The circuit still uses light bulbs, but...
This circuit is from Linear Technology 2005 documentation. The circuit is based on company...
The integrated circuit used in this power supply is no longer very common in power supplies today....