This circuit uses a contactor having been found in a 1987 publication. More modern equivalent devices may be used. The circuit has neon indicator lamps.
This circuit uses a photo-transistor to trigger a circuit sourcing a square signal for the output. The...
This circuit makes use of an uncommon integrated circuit. It can provide a power of 6 W when...
The circuit is from an 80's publication, but the components are current, only special type diodes...