In use telephone indicator (CB8665E)

This circuit was found in a 90s Electronics Now. The circuit can use a TIC106 for the SCR.

Locomotive whistle (CB7507E)
This railroad model circuit was found in a 1960 Sylvania transistor manual. The components are from that...
Overload sampler (CB8354E)
This circuit samples the current in a load and in case of excessive value it activates a...
Multiplex Series Lamp (CB6874E)
We found this circuit in a 2004 documentation. The circuit consists of a standard lamp for testing...