This 80's circuit uses an audio amplifier to obtain a symmetrical source from a single source. The maximum current is on the order of 1.3 A and the input voltage must not exceed 20 V.
This circuit with different colored indicator LEDs has an expanded scale. We found it in the March...
This circuit can be used as an answering password system in a store, office, or other location....
This circuit is from the American magazine that no longer exists Science & Electronics,...