Freeze Alarm (CB14454E)

The circuit of a 1968 publication can be implemented with more modern transistors such as BC548 for NPN and BC558 for PNP.

Unijunction Metronome (CB12281E)
This circuit is from a 1991 publication, but it can be assembled with more modern components. We...
Precision Current Source (CB14078E)
This circuit provides a current given by the components calculated according to the formula next...
Audio Booster (CB23540E)
Published in Radio Electronics in October 1963, this circuit increases the audio output of a small...