Leak Detector (CB22456E)

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

Dual-intensity LED (CB22128E)
This circuit switches the brightness of the LED. We found it in an English documentation....
Timed Photo-Electric Automation (CB13146E)
The circuit shown in the figure triggers a relay when S1 is pressed, but this only in the absence of...
Astable (CB19898E)
This astable multivibrator is one of the many configurations that we have in this section and on...