This circuit was found in documentation from the 1980s. It is powered by the audio signal that must be cut. Transformers are the critical components and transistors are 2N2222.
This timer was found in the Texas Instruments 1996 linear applications manual. The relay must be...
This circuit compares two light intensities, providing the indication on an analog instrument. The...
This circuit was obtained in a 1983 publication. It is a 1-transistor voltmeter, capable of...