Leak Detector (CB22456E)

We found this circuit in a Popular Electronics from 1992. The transistor is general purpose, assuming equivalent.

Null Detector (CB11550E)
We found this circuit in the Texas Instruments' Linear Circuits Applications. It uses an...
Pulse Generator 4093 (CB19413E)
The integrated circuit of this pulse generator is 4093 and the frequency can be between a fraction of...
4066 Latching Touch Switch (CB25241E)
This circuit was found in the November 1989 Radio Electronics magazine. Power supply depends on...