This circuit was obtained in an Electronics World of 1968. The operational amplifiers ones are types of the time, no longer used today. The circuit responds from less than 20 Hz.
We found this TTL circuit with the 7400 in the January 1975 Radio Electronics magazine. The power...
This adjustable direct current source circuit uses a triac operating as a variac. The circuit is...
This radio's transistor is powered with the signal's own energy, producing its amplification....