This circuit was found in a 90s Popular Electronics. It is possible to analyze the voltages of an automotive battery. The integrated voltage comparator circuit admits equivalent.
Below are two frequency filters for receivers using crystals. The crystals must have the frequency of...
We found this circuit in a Radio Electronics from December 1963. The circuit combines valves and...
This circuit published in the November 1964 Radio Electronics magazine powers a light bulb but can...