Voltage regulators kits on ebay.

Hi !
I see many voltage regulators kits on ebay, assembled and not.
I wonder if anyone has experience of any of them.
My need is for 12V/1A to power a dac.
These 12V should as clean as possible.
I am about to test different dacs all using 12V and I would like that the power supply is not the limiting component.
At present i am using a smps AC adapter but I read that linear psu could be better
both in terms of residual ripple (0.1% versus 1% Vout) than of suppression of noise coming from the mains.
I have already a 12V mains transformer at hand that I would like to use initially.
I like EI type because I understand they have a better suppression of high Hz mains noise, the Achilles's heel of many single chip regulators.
I also see that many commercial high quality linear power supplies come with EI transformer.

[IMGDEAD]https://www.be-electronics.com/v/vspfiles/photos/HSC24-2.4-2.jpg[/IMGDEAD]

Thanks a lot in advance for any advice.
Kind regards, gino
 
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"These 12V should as clean as possible.
I am about to test different dacs all using 12V and I would like that the power supply is not the limiting component"
I suggest you Eliminate the AC power supply and use a Battery for Performance testing

Hi and thanks a lot for the very valuable advice.
I suspected that :( i mean that batteries based power supplies are the best.
I was watching a video from Linear Technologies. They were using a battery to power a voltage reference to get the best performance.
This sounds to me the ultimate evidence of their intrinsic superiority.

But let me describe a little better my situation.

The dac is firm. I like it and i intend to keep it, at least for a while.
Problem is that i see some differences in its noise floor using different 12VDC power supply.
For me a noise floor that is not flat at least in the audio band is not acceptable.
And especially in the low Hz it tends to go up.
It must be flat also there, aligned with the rest of the band.
Its performance looks to be dependent on the actual power supply used.
So in the end i am looking for a good power supply that gives me the flattest and lowest noise floor obtainable from this dac
For practical reasons i would like to stay away from batteries, even if in this way i will not reach the very best performance obtainable with the dac.
I have to live with that.
I had already batteries ... they were a mess.
I have already set on the type of transformer. This is another fixed point.

EI_Transformer.jpg


I am looking at 12VAC units.
But when it comes to regulators ... i am lost in the huge choice of kits, assembled or not :confused:
The idea is to put the regulator in the case close to the dac and keep the transformer outside.
In this way both vibrations and EMI generated by it will not be an issue.
I would love batteries but they are just too much inconvenient.
Thanks a lot again, gino
 
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what DAC are you gonna feed ?

Hi !
it is not a diy unit but a commercial usb soundcard.
The noise issue has been highlighted by a review with some lab measurements.
The stock smps shows some noise issues (see picture)
Others have already replaced it with linear ones or better smps.
Main problem is that space inside is very tight (see picture)
So the idea is to use an external new psu.
Kind regards, gino
 

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This may help...My assumption is that your xfmr is 18-0-18 (0 corresponds to the center tap). That voltage is probably a little high, but it would work fine given enough heatsink on the LM7812. You may have to go up a bit on the voltage rating for the 4700 uF cap, to 35 volts, to have more margin given an 18-0-18 transformer.
 

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This may help... My assumption is that your xfmr is 18-0-18 (0 corresponds to the center tap)
That voltage is probably a little high, but it would work fine given enough heatsink on the LM7812. You may have to go up a bit on the voltage rating for the 4700 uF cap, to 35 volts, to have more margin given an 18-0-18 transformer

Thanks again. I see you recommend the LM7812 as regulator ?
However i am very willing to buy a new transformer with a voltage better suited. I have already seen cheap 12VAC on ebay.
I see it as an investment. I am going to use it for some time.
Regards, gino
 
7812's do just fine. Some people like fancier stuff, s a perfectly reasonable way to get going.

The transformer will be ok...It's hard to say what really comes out of it without a good model. Heck...start with that one...you can measure the bulk DC at some point and pick a bit lower transformer voltage, maybe 14-0-14.

You just need to make sure there's enough heatsink on the 7812.
 
7812's do just fine. Some people like fancier stuff, s a perfectly reasonable way to get going.
The transformer will be ok...It's hard to say what really comes out of it without a good model. Heck...start with that one...you can measure the bulk DC at some point and pick a bit lower transformer voltage, maybe 14-0-14.
You just need to make sure there's enough heatsink on the 7812

Thanks a lot again. Fixed voltage regulators are indeed very convenient.
One thing i have discovered is that many circuits have indeed a very good PSRR
so maybe extreme sophisticated power supplies are not always needed.
Kind regards, gino
 
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