VU meters

This is a complicated subject. Do you just want blinking lights or do you want a useful tool? There are some standards out there but the real issue becomes ballistics. How fast does the needle (or LED's) move? Hold times? A crappy meter is worse than no meter at all.

So metering design depends on what you are trying to measure. If its signal level on digital recording, you need to make damn sure you don't run out of bits. If its for a power amp, clipping / power output, thats a different circut.

AES has some really good info out there.