Simple noise indicator using an analogue meter

[DeanO1000]

Hi there. I need to build a simple room noise level indicator that would incorporate an analogue (needle) meter, not LEDs with a low voltage power source.Say around 5 to 9 v. Any ideas? Are there any ready built units out there? Thanks !!

 

[Harald Kapp]

This one looks reasonably simple. Works from 18 V, so use 2 * 9 V batteries in series.

Or search for "analog sound level meter circuit".

Don't despair: although most sound level meter circuits feature an LED bar graph display, the circuits can be used for your purpose, too. Simply replace the bar graph IC and the LEDs by an analog meter. These ICs register the input voltage and drive the respective number of LEDs. But the input voltage can be used to drive an analog meter directly. Some scaling using resistors may be required to match the voltage from the microphone amplifier to the range of the analog instrument.