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5V 3A PSU

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Ernie View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ernie Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 2020 at 7:54pm
Originally posted by Graham Slee Graham Slee wrote:

Originally posted by Ash Ash wrote:

We could discuss the necessary calculations, hazards and heatsink config best for adequate passive heat dissipation.


Quite happy to do so. Probably best to do it here, stage by stage.

Hi Graham,
We talking about powering streamers into dacs and the like though not a pre amp. Worth a punt building an add-on?


Edited by Ernie - 06 Jun 2020 at 7:55pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ash Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jun 2020 at 11:11pm
Graham, slight change of rationale with the 12V PSU.

How about I buy the 5V 3A product but you supply the internals for 12V 3A alongside it as well. Then I can swap in what supply voltage I need for the product that I want to power and in the case of using the 12V internals, I will have to add further heatsinking to the case to increase heat dissipation before I can use it?? I will still consult you closely before handling anything on the mains side.

By the way, my mini-PC is 12V but is rated at 15-25W so less than 3A. I will be trying to keep it as solid-state as possible. One external USB HDD and a USB CD/DVD drive would be the only "motorised" peripherals I would have drawing current and they would only be used sometimes and maybe not at the same time. As long as I respect that I need to keep power draw down, perhaps the PSU temperature won't rise to an unacceptable level.


Edited by Ash - 12 Jun 2020 at 11:24pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jun 2020 at 6:45pm
12V 2A is a bit easier to do than 12V 3A. However, I had hoped to get across the impact of any voltage change in a design like this, that it isn't just the voltage, but all the things I calculated for you (and other readers) a few posts back.

I am flattered by those members who think I somehow have magical skills, but I am sorry to have to inform you, that it's just engineering. In fact, most of hi-fi seems to be dominated by thoughts of magic being at play. There is no such thing as magic, but confidence tricks.

24 or 25 watts, is still more than 15 watts, and will still require larger heatsinking, and obviously a different transformer.

It will most likely cost me £4,000 in prototyping and having a few cases made, and that's without any payment for my time. How do I know? Well, that's how much the 5V 3A version has cost me so far. Switchmode is stacks cheaper and available off the shelf.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ash Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jun 2020 at 6:56pm
And I guess there is no guarantee that it will make a significant difference when powering a computer, which has other sources of high frequency noise. Perhaps it would be wise for me to just forget it then.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jun 2020 at 10:04pm
With around 2 trillion transistors switching at 4 GHz, I don't think a vintage 100Hz ripple type power supply will make all that much difference. Then again, it might cause it to crash!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ash Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jun 2020 at 11:05pm
So you are actually sceptical that a linear PSU of any voltage will offer any audible improvement for a single board computer or streamer circuit? The switching noise of the circuitry during normal functioning perhaps would offset any reduction in noise from the supply.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jun 2020 at 3:56am
A processor running at 4GHz clock speed presents a highly harmonic constantly changing structure of charges, which might be handled better by the high frequency and low impedance characteristics which are a prerequisite for switchmode power conversion.

A 10MHz to 25MHz clock speed of something dealing with SPDIF (or even audio frequencies), which are more "analogue" in nature, might be served equally by either type.

The conventional 50/60 Hz transformer-rectifier supply requires aluminium electrolytics able to handle ripple current on a roughly 10:1 diode charge ratio 100/120 times per second, which means the ripple current is approximately 10 times the load current. For 3A the ripple is 30A.

With switchmode, the diode switching is on the mains side, prior to any capacitive load.
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