This two-channel bargraph meter uses a single KAA2281 integrated circuit. Found in the January 1991 issue of Radio Electronics magazine. The stereo circuit drives 2 scales of 5 LEDs.
This circuit uses an LDR as a sensor to trigger an LED indicator at a preset lighting level. The...
We found this circuit in an American publication from the 80's translated into Portuguese. The...
We found this circuit in an old French documentation from the 70s, but it can be assembled using...