An DIY RF decibel (or power) meter is an indispensable instrument in any radio workshop. Unfortunately, accurate, wideband models are fairly expensive, and home-constructed ones are generally not ...

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 ...