We found this passive circuit in the February 1995 Electronics Now magazine. The circuit is passive, presenting only attenuation that must be compensated by an amplification stage.
This circuit warns when the headlight bulb is on. We found it in a Popular Electronics from the...
The oscillator shown in the figure keeps its frequency constant in an active cycle adjustment...
This circuit was found in an Argentine publication from the 1970s. The circuit can be assembled with...