When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. The unbridled development of radio broadcasting in the 1920s and 1930s demonstrated the need to ...

While refurbishing an ageing audio mixer, I decided that the level meters needed special attention. Their rather horrible 100 µA edgewise movements had VU-type scales, the drive electronics being just ...

This circuit uses two quad op-amps to form an eight LED audio level meter. The op-amp used in this particular circuit is the LM324. It is a popular IC and should be available from many parts stores.