Given its appearance in one form or another in all but the cheapest audio gear produced in the last 70 years or so, you’d be forgiven for thinking that the ubiquitous VU meter is just one of those ...

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.

In almost every measurable way, a lossless digital audio file is superior to any analog media. This doesn’t mean that analog audio isn’t valuable though; plenty of people appreciate the compression, ...