Leak Detector (CB22456E)

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

Operational Pulse Width Modulator (CB5360E)
We find this circuit in an 80s operational amplifier documentation. The circuit applies to any...
Low Resistance Meter (CB12193E)
We found this circuit in a 1981 publication. Its purpose is to measure resistances of very low...
Sound Dynamometer (CB16249E)
According to its author, this device indicates the amount of force applied to the sensors. The...