Here the 12 LED VU meter circuit. This is a simple visual indication of the audio level signals, adaptive to various user needs. Can be adapted to different input levels, adjustable by trimmer TR1 (state) - TR2 (Gain), then rectified by diodes D1-D2 (standard negative mark-recovery periods) and driven in the main circuit indication, consisting of the diodes D3 up to D13, transistors Q2-Q13 and materials that exist around them.
The visual indicator is taken from the series of diodes LED LD1-13. Each Led illuminates when the level changed during about 0,65 V. The power requirements are 100 ma full term. We can add as many steps we want LED, always assuming the power where you need the new LED.
Components List
| R1 = 47Kohm R2,3 = 1Mohm R4,R7 = 1Kohm R5 = 100ohm R6 = 18Kohm R9,11,13,15,17 = 560ohm R19,21,23,25,27 = 560ohm R29,31 = 560ohm R8,10,12,14 = 4.7Kohm R16,18,20,22 = 4.7Kohm R24,26,28,30 = 4.7Kohm C1 = 10uF/25V C2 = 100nF/100V MKT C3 = 4.7uF/25V | C4 = 4.7uF/25V C5 = 10uF/25V C6 = 47uF/25V C7-8 = 100nF/100V TR1 = 100Kohm Trimmer TR2 = 4.7Kohm Trimmer LD1 until LD7 = LED Green LD8,LD9,LD10 = LED Yellow LD11,LD12,LD13 = LED Red D1 until D13 = 1N4148 Q1 until Q13 = BC550C - BC549B IC1 = TL071 IC2 = 7812 [With Heatsink] All Resistors is 1/4W 1 -5% |
12 LED VU Meter Circuit source page: users.otenet.gr