Audio Level Meter
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
- 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.