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.
Found in an English documentation from 1989, this circuit uses components common today. The...
The LED frequency flashes depends on the value of the capacitor tested according to the table. We...
Found in a Popular Electronics from the 90s, this circuit generates a signal that depends on the...