This is a single function indicator designed with discrete elements.
Watch Video : http://youtu.be/zRfHpgFAAQA
The circuitry consists of a level indicator for low frequency signals.
The LED indicator is mono type. Dot bar type.
Input signal is standard - 0.750 V (Low level). VU meter not work speaker output (work only line level signal - 0.500 to 1V).
Input level control - trimmer-potentiometer.
12 LEDs.
Supply voltage DC - 9 to 15 V (max 120mA), (You can use the car battery).
Overall
dimensions PCB 105x37mm (4.13"x1.45").