Peak Indicator


A simple circuit, peak indicator of tops of musical signal. Each time where the level of signal exceeds the level + 4dB, turns on led D1. It is useful in each channel of console of sound, in final amplifiers or in that other application, to we needed. With the prices of circuit, the indicate begins with levels above + 4 dB (1.25V rms). For adaptation in different levels of signal, we can use a trimmer, before capacitor C1.

Circuit Diagram:

Peak Indicator-Circuit Diagram


  • R1 = 10K
  • R2 = 1.2K
  • R3 = 220K
  • R4 = 4.7K
  • R5 = 4.7K
  • C1 = 47uF-25V
  • C2 = 2.2uF-25V
  • Q1 = BC550C
  • Q2 = BC550C
  • D1 = Red LED


  • It can be assembled on a general purpose PCB.
  • It can be powered from a 12V-15V regulated power supply.