This circuit was found in Motorola documentation from the 1980s. The components are of the time, not currently common as operational and opto receiver.
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...