Hi everyone. It's been a good while and think time has left me learning things all over again. I’ve been having a bit of trouble getting this Craig Anderton designed VU meter to function (rather embarrassingly). I’ve put it on the breadboard and can’t figure out what I may be misinterpreting or doing wrong.
It’s based around the NSM3916. I’ve instead used an LM3916 in its place. I’m hoping my pinouts are correct and I’m translating things right, and it seems that last section of the circuit works fine isolated after putting some voltage into the input for testing. The 10K pot on the REF OUT/ADJ. is there for fine tuning and will be replaced with a resistor's once I settle on the right value(s). Also, I’m only using the lower 6 out of the 10 LED’s offered but those are the only caveats I’ve made.
But once I try to bring in everything before that with the TL071’s input buffer, and peak to peak voltage and detector, I get nothing out of the LED’s. After scouring the first 3/4ths of the circuit again and again, I still can’t seem to figure out what I may be missing or doing wrong. I’m hooking it up guitar/amp wise per the suggestion of the article and not being used in conjunction with any other circuits (yet).
Here is the schematic out of the book DIY Projects for Guitarists by Crain Anderston and a scan of the whole article to boot if it may help anyone else and if it offers context to something I may not be paying attention to or getting wrong. I’d love to get this particular circuit working even though the parts count is high (I want to use this with a treble booster lol), but seems to offer everything I need in a VU meter that was designed just to respond to a guitar. I may end up using something else that does just the same minus a couple TL071's but would love to give this a go.
If anyone could spare a few moments to look over my layout vs the schematic I’d be really grateful. I must be doing something wrong with the bipolar power supply but have tried every iteration of hooking things up that make sense to me and still getting nowhere. Thanks for reading folks and can post a revised breadboard layout if that will help anyone in the future get out of the same rut.
