Light test (CB8789E)

This light-sensing probe was found in a 90s Popular Electronics. The circuit detects light sources by triggering a buzzer.

Zero Crossing Detector LM139 (CB15251E)
This circuit is from the 1993 Motorola Linear Interface Circuits. The source does not have to be...
25 MHz band Receiver (CB19558E)
This range is normally used in marine communications as indicated in the 1989 documentation. The...
Relay shield (CB8836E)
This shield circuit is from a 1968s Motorola documentation. The relay is according to the supply...