The sensor of this circuit is a photodiode. Equivalent operations can be used, and the instrument can be replaced by the lower current range of a standard multimeter.
This circuit was found in the September 1976 issue of Radio Electronics magazine. The circuit is...
We found this circuit in a 1995 documentation. It operates in the 3.5 MHz band that corresponds to the 80...
This 3-decade operating range VCO was found in a 90s Popular Electronics. The circuit uses...