Motorcycle headlight monitor (CB9117E)

This simple circuit was found in Popular Electronics from the 1980s. The circuit uses an LED as an indicator.

Peak Detector (CB13262E)
We found this circuit in a technical documentation from the 70s. It can be implemented with more...
Linear Optocoupler (CB12458E)
We found this shield circuit in a 1991 technical documentation. The phototransistor can be...
Bridged output amplifier (CB23540E)
This circuit was obtained from a Radio Electronics from October 1963. The 4 transistors must be...