Found in a 1924 documentation, this circuit is powered by 3 batteries, two of which are high voltage. The output is a high impedance headphone jack.
This circuit appears several times in this section and on this site, obtained from different...
This circuit was found in a General Electric documentation from 1970. Equivalent transistors can be...
The circuit shown consists of a NO and NC sensor system for alarms. The output must be connected to a...