VU Meter 2


A circuit of measurement of level based on a typical application of National. The circuit round the IC1 makes input adaptation and amplification with the trimmer TR1 [GAIN]. The circuit round the IC2 makes half-wave rectification of acoustic signal. With switch S1, we select the type of indication, that we will have from the LED. With the prices in resistances R6 and R7 that exists in the circuit, the level of signal, in the entry is 7.8V (gain of first stage IC1, is one), and the difference of level between the LED D10-11, should are 3 db. The positive department of supply, should have the possibility of giving more current, one and it is overloaded with the current of LED..

Circuit diagram

Circuit diagram

Part list

  • R1-2=10Kohm
  • R3-4=10Kohm
  • R5-8-9=1Kohm
  • R6=330Kohm
  • R7=62Kohm
  • TR1=47Kohm Trimmer
  • C1=100uF 25V
  • C2-5=10uF 25V
  • C3-4=100nF 100V
  • C6=1uF 25V
  • S1=mini Switch
  • D1-19=LED 3 or 5mm any colour.
  • D20-21=1N4148
  • IC1=TL 072
  • IC2=LM3915
  • IC3=LM3916