Uses an array of LED's to indicate the approximate input voltage level of up to a peak of 5v at 1v intervals. Neat little circuit, with a fairly low component part list. Simply uses multiple resistor voltage dividers for biasing each transistor, the resistors of each voltage divider must be calculated to output a voltage equal to the Vbe of each transistor (about 0.75V for BJT's) with whatever input voltages you desire at ideally equal intervals, such as 1V in this circuit. Could be used to put on a cool music display for example.
