Lead Acid Battery Charger (CB26301E)

This power charger was found in a 1990s issue of Popular Electronics. Integrated circuits must be equipped with a heat sink.

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Contrast Meter (CB26202E)
This circuit for photography uses was found in the Electronics Experimenter Handbook Special...
Lock Timer (CB5980E)
It is like to the previous circuit with a lock that keeps the LED on at the end of the timer. The...
Dual Sensor (CB21521E)
This circuit, with two operationals, was obtained from an old American publication. Operational...