This receiver for a modulated light intercom was found in a 90s Elektor. The audio amplifier can be replaced by an equivalent. The sensor can be any phototransistor.
This sensitive field strength meter was found in 1993 documentation. The instrument may be the...
This circuit was found in a 1967 General Electric manual. It is intended for the control of high...
The figure shows how to vary the output voltage of a 7812 regulator between 12 V and 2 V less than...