Micro metronome (CB20743E)

This simple CMOS metronome circuit can be mounted in a small box, providing both sound and light sources.

Sensitive Metal Detector (CB4406E)
This circuit was found in a 1992 documentation and has excellent sensitivity, using components that...
Turn Counter with Calculator (CB16443E)
This practical idea from a 1992 documentation shows how to count the turns of a winder using a...
Sensitive relay (CB22289E)
In this circuit from the 60s, the power supply is made with 22.5 V, which is the voltage of the...