Low battery indicator 555 (CB9551E)

This circuit can operate with different voltages, depending on the zener used. We found it in a 90s American documentation.

Micro metronome (CB20743E)
This simple CMOS metronome circuit can be mounted in a small box, providing both sound and light...
Capacitance Switch (CB4993E)
Although indicated in the original publication of the 1980s as a capacitance switch, the circuit...
Chroming with Solar Energy (CB18492E)
In the figure below we have a simple way to do chroming, silvering or another type of...