Charger protection relay (CB26312E)

This circuit was obtained from an Elektor magazine from the 90s. The circuit is to protect batteries while charging.

Parallel regulator (CB22266E)
This low current parallel or shunt type regulator was found in documentation from the 60's. The...
1 kHz Tone Recognizer (CB1428E)
This circuit is found in a 1975s documentation for radio amateurs. It was developed to recognize a...
Audio Relay (CB13614E)
The displayed relay operates with an audio signal applied to the input. The transistors can be...