Author Topic: Anderton NSM3916 VU meter breadboard layout help?  (Read 795 times)

Bandwagonesque

Anderton NSM3916 VU meter breadboard layout help?
« on: January 30, 2023, 05:41:07 PM »

Hi everyone. It's been a good while and think time has left me learning things all over again. Iíve been having a bit of trouble getting this Craig Anderton designed VU meter to function (rather embarrassingly). Iíve put it on the breadboard and canít figure out what I may be misinterpreting or doing wrong.


Itís based around the NSM3916. Iíve instead used an LM3916 in its place. Iím hoping my pinouts are correct and Iím 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, Iím only using the lower 6 out of the 10 LEDís offered but those are the only caveats Iíve made.

But once I try to bring in everything before that with the TL071ís input buffer, and peak to peak voltage and detector, I get nothing out of the LEDís. After scouring the first 3/4ths of the circuit again and again, I still canít seem to figure out what I may be missing or doing wrong. Iím 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. Iíd 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 Iíd 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.






PRR

Re: Anderton NSM3916 VU meter breadboard layout help?
« Reply #1 on: January 31, 2023, 12:57:48 AM »
Do you understand "bipolar" power supply? I think the opamps want a negative supply rail.

I do not understand all of Anderton's rectifier. The LM3916 datasheet has others. I can endorse Fig 18 as simple and effective. And works single-supply!
https://cdn.sparkfun.com/datasheets/Components/General%20IC/lm3916.pdf

Google "sparkfun LM3916" brings up more LM3916 fun.
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ElectricDruid

Re: Anderton NSM3916 VU meter breadboard layout help?
« Reply #2 on: January 31, 2023, 05:35:40 AM »
+1 what Paul said. You need a bipolar supply, both +9V and -9V.

Rebuild it using Red for +9V, Black for -9V, and Green for Ground. Don't confuse -9V with Ground.

The current layout has lots wrong with it and you'd be better off starting from a clean slate.

PRR

Re: Anderton NSM3916 VU meter breadboard layout help?
« Reply #3 on: January 31, 2023, 10:46:29 PM »
> You need a bipolar supply, both +9V and -9V.

I think, using the Fig 18 rectifier, and possibly any standard single-supply gain stage, it can be done single supply.

Of course last time I thought that I ended up having to build more stuff for factors I overlooked....

We know that "LED VU meters" are cheaper from the Asian barter sites than they ever were at Allied or RadioShack?
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