Audio level meter circuit

Audio Level Meter

Description

A simple and low cost audio level meter circuit that can be used to measure the audio level of your sound source.This circuit is a valuable tool for those who are interested in audio circuits.

The circuit is designed with a flat frequency response in the range of  20Hz to  50Khz. Input sensitivity is 100mV for a FSD on a 100uA ammeter.The circuit is build based on on two common emitter amplifiers, the first stage has a preset resistor R3 (1K) which may be adjusted for a FSD. The last stage is biased to operate at about 1/2  the supply voltage for maximum AC voltage deflection. C2&C2  (10 uF) acts as a filters through which audio frequencies  are passed .  The full wave bridge rectifier converts the signal to a varying dc voltage. The meter will show this voltage as the output reading which is proportional to the input voltage level.

Audio Level Meter Circuit Diagram with Parts List

sound level meter-VU level meter

Notes.

  • The meter reading is instantaneous and it will not provide you with a peak to peak reading.
  • To calibrate the meter, provide a  1Khz 100mV sine wave at the input and  adjust R3 to get a full scale reading on the meter.
  • Use a well regulated & filtered 12 V supply for powering the circuit.

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2 thoughts on “Audio level meter circuit

  1. Watson

    The meter is labeled 1 microamp full scale deflection. I’ve never heard of such a beast. If there is such a thing, it would be expremely expensive. It should probably be labeled 1 milliamp or 100 microamps. But since the meter is not inside of a feedback loop, the readings will be incorrect at low levels.

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