This circuit also detects IR, providing LED indication. The circuit is used to indicate humidity in bench tests. We found it in the Radio Electronics magazine of February 1990.
This circuit converts inductances on two scales into voltages. The circuit was obtained from a...
Placed in the vicinity of a telegraphic transmitter (CW), this circuit produces an audible signal on...
This circuit was found in a 1967 RCA documentation. The components are of the time. The circuit...