This analog frequency meter for low frequencies was found in Radio Electronics magazine from July 1958. The circuit has several scales with the frequencies indicated in the diagram.
This circuit was found in documentation from the 1980s. The transistor depends on the desired...
We found this circuit in a 1985 technical publication. The circuit uses PUTs to drive lamps....
This type of circuit, found in American documentation from the 1980s, triggers producing output...