This circuit can easily be assembled on a small piece of prototyping board. Use low-current types for the LEDs. They have a low forward voltage and are fairly bright at current levels as low as 1 mA.

This sound level meter circuit can be used to control the intensity of a sound recording or in a disco. It has 5 measurement domains between 70 and 120 dB; reading accuracy is 0.5 dB. Microphone M1 is ...

Usuallyyour meter will be bought or adapted for a specific measurement and youwill not have to make special efforts to get it to read what you want.Or your schematic will specify the sensitivity of ...