Using the LM170 integrated circuit, this circuit was found in the May 1970 Radio Electronics magazine. The transistor is general-purpose, and the potentiometer adjusts the gain.
This circuit uses half of the LM158 operational double but can be used in the series as the LM258,...
This circuit generates audio tones in a speaker with controlled frequency and volume. The...
This circuit was obtained from an article in Radio Electronics magazine in October 1966. It...