VU Meter 1


It is a simple circuit of optical index of level of sound signals, adapted in various needs of user. It can be adapted in various levels of entry, regulated from trimmer TR1 (Level) - TR2 (Gain), then it is rectified by the D1-2 (cutting off of negative periods of signal-rectification) and drived to the main circuit of index, that it is constituted by D3...D13 , the transistors Q2-Q13 and the materials that exist around them. The optical index him we take from the line of LED LD1-13. The each led turns on when the level is altered at 0,65V roughly. The requirements in current are 100 ma with complete index. We can add all units LED we want, always calculating the current where they will need the news LED.

Circuit diagram

Circuit diagram

Part 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
  • TR1=100Kohm Trimmer
  • TR2=4.7Kohm Trimmer
  • 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
  • LD1-7=LED Green
  • LD8-10=LED Yellow
  • LD11-13=LED Red
  • D1-13=1N4148
  • Q1 ....Q13=BC550C - BC549B
  • IC1=TL071
  • IC2=7812 [With Heatsink]

All Resistors is 1/4W 1 -5%