Vu Meter driver

Spencerleehorton · Dec 23, 2016

Hi,
I have bought a vu meter driver and I'm a bit confused with it.
I had thought that I would be able to feed an AC signal in but this doesn't seem to work?
I will trace signal and see how far it's getting.
It's a cheap one off eBay but I might build my own if this doesn't work.

ruffrecords · Dec 23, 2016

Can you post a link to the one you bought?

Cheers

Ian

Spencerleehorton · Dec 23, 2016

http://www.ebay.co.uk/itm/VU-Meter-Driver-Board-Audio-Level-Power-Amplifier-Board-for-TA7318P-DENON-AC9-20-/181909481403?var=&hash=item2a5aa667bb:m:mZOTomcaXkkhzQlebsqpgEA

and I've attached the schematic

Martin Griffith · Dec 23, 2016

looks wrong, the pins of the opamp pins 3 and 5 , shown as ground, should be at 1/2 supply rail

Spencerleehorton · Dec 23, 2016

i wondered why it wouldnt work!!, what a con! so i need to get 12v to pin 3 and 5 right?

kambo · Dec 23, 2016

Spencerleehorton · Dec 23, 2016

if its blown can i replace it for a 5532?

Spencerleehorton · Dec 23, 2016

im gonna need a bit more help here to understand how this should work from this schematic!!
i can see that the voltage pins 4 and 8 are correct but what and where should be feeding pins 3 and 5?

Martin Griffith · Dec 23, 2016

Done a crap mod, but two equal resistors, in series across the VCC GND and the middle goes to pin 3 and 5, its a pseudoground, a little cap say 0.1uF between my wonderful pseudo ground and real ground might be needed. Dont think I've forgoten anything obvious. edit, don't forget that their cct maybe drawn INcorrectly, check the volts wrt the real ground and pin 3 and 5

Rob Flinn · Dec 23, 2016

I would have put an electrolytic across each of your 10k.

Spencerleehorton · Dec 23, 2016

So should I put a 10uf in parallel of both 10k?

Rob Flinn · Dec 23, 2016

That's what I would do.

Spencerleehorton · Dec 23, 2016

Ok cool, if there was a like button I would have used it!!

I'm going to draw It out in eagle and do my own once I know it works!!!

Spencerleehorton · Dec 23, 2016

So just to check, if I use the schematic below but change C3 to 220uf / 25v for soft start?

Rob Flinn · Dec 24, 2016

Your C5 isn't connected across R15,it's connected across R14 & R15.

I don't think changing C3 will chive your goal of a soft start.

Spencerleehorton · Dec 24, 2016

Ah ok,

So could you suggest a way of doing it correctly then please?

Rob Flinn · Dec 24, 2016

I'm not really sure why you would want a slow start on a meter.

Spencerleehorton · Dec 24, 2016

I read that the initial power up would deflect the needle and give it a thump, that's the only reason why, if it doesn't do this that's fine.
Where would be the best place to put it then within an API-312 or Neve 1290 preamp?

Spencerleehorton · Dec 24, 2016

I will redraw schematic and submit for review before I do anything else but first Christmas!!!
Have good one everyone!!

PRR · Dec 24, 2016

That schematic has SO many problems, I think they were kidding you.

And so many that I don't want to start re-designing a cheap bit of junk kit which cost less than a piece of my brain.

Is a bi-polar +/- supply available?

Vu Meter driver

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