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mkv 26th June 2012 07:53 AM

How to power these boards on DC?
Hey guys,

Forgive my beginner questions, I'm learning as I go along.

I'm putting together a little DIY audio project, and I found this great preamp board which I want to use. The problem is though that the board specifies that it requires an AC supply, however the project is mobile and will be running on DC. Am I able to run this board on DC somehow or do I have to find another preamp?

The preamp is pictured here:
NE5532 Preamp DIY Treble Mediant Bass Blance Volume Board Aseeembled $20.73 Free Shipping

It seems alot of these preamps using the NE5532 require an AC aupply. How can one get around this?

Thanks for your help!

DF96 26th June 2012 09:08 AM

You could try feeding in a DC supply, say 20-0-20V. The AC probably goes straight to a bridge rectifier so you can feed DC through it. This device probably will not function from a single DC supply without some reworking - would be easier to start again if that is your aim.

mkv 26th June 2012 09:13 AM

I have had a quick look around for an off the shelf dc to dc supply, say 12V DC to 6-0-6, or 24V DC to 12-0-12.

Haven't found anything...

It's easy to find DC powered class D power amps for what I'm looking for, but I can't seem to find any volume/bass/mid/treble preamps which run on DC for my needs... Can anyone suggest something?

Thanks for the help!

Minion 27th June 2012 11:27 PM

The board has on board rectifiers , regulation and filtering for turning AC to filtered DC .....
If this is going to be a mobile you can use 2 x 9v batteries in series to get a +/-9v dc supply , You would need to mod the Rectifier/regulator section of the pcb to accept a DC supply , it could be as easy as installing a couple jumpers .....


wwenze 28th June 2012 05:35 AM

I see 3-pin regulators... likely to be 12V or 15V...

MarianB 28th June 2012 07:46 AM

That board requires AC suply because it has it's own bridge rectifier and filtering caps, and stabiliser just after them, the stabilisers seem to be 7812/7912 so it would be as simple as feeding the DC supply voltages directly on the capacitors pins ( the 2200uF/25V ones ), no modification needed, just be careful to respect the polarities. If DC supply voltages are smaller than 12V ( or equal ) but they are from some battery so stable than you need to bypass the stabilisers, just remove them and with a jumper feed the voltages from the caps to the Vout of the stabilisers, it's sound complicated but in fact it's verry easy.

DF96 28th June 2012 10:05 AM

You can't simply apply a single supply to a circuit designed for a dual supply. Single supply is less popular now, but I would have thought that the internet still has lots of simple preamp circuits for 12V. Just look for them. There is a 12V based tone control being discussed in another thread on here right now.

MarianB 28th June 2012 10:16 AM

I do not remmber saying that he should use single supply, ofcourse it should be a simetrycall DC supply ( i sayd voltages, not voltage ), so as someone else sayd use two 9V batteryes and all should be ok, just bypass the stabilisers.

DF96 28th June 2012 10:52 AM

No, he implied he wants to operate from a single 12V or 24V DC supply - presumably a battery? See post 3. He can of course use two batteries.

MarianB 28th June 2012 11:00 AM

Ok sorry then... as i see he sayd that he was looking for some DC to DC converter from a sigle supply to simetricall one ( for example 24Dc in <=> +/-12VDc Out...) , but he did not find anyting ( he might try floating ground..), i might be wrong but this is what i understud from message #3.

Two 9V batteries are more than ok, the power consumption for that board is verry low so the batteryes should last long time, and they are cheap.

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