This 3-digit digital gauge was found in the July 1900 issue of Radio Electronics magazine. The circuit is based on the CA3161 and CA3162 A/D converters of the time.
This circuit from an old documentation uses an optocoupler to control the feedback. FET is...
We found this circuit in a publication for radio amateurs in 1974. The bipolar transistors can be...
This circuit was found in a documentation for radio amateurs from the 70s. The integrated circuits...