Audio Cable Tester (CB3827E)

This simple circuit tests both monophonic and other two-wire audio cables. The circuit is powered by two common batteries.

Random Neon Flasher (CB14780E)
We found this circuit in a 1981 publication, when it was still possible to find 22.5 V batteries (used...
Pulsating audible LED (CB20946E)
This circuit was found in an old Popular Electronics. It causes an LED to pulse and, at the same...
Micro metronome (CB20743E)
This simple CMOS metronome circuit can be mounted in a small box, providing both sound and light...