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  #1  
Old 07-31-2017
Aaron A Aaron A is offline
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Default Power Supply Electronic Noise

I have some questions on power supplies that cause electronic noise. I work in a manufacturing facility and have some very sensitive electronics affected by noise. If I use the PC power supply (12VDC) to power my equipment, I amazingly get good (noise free) results. Iím actually amazed with this, as I heard PC power supplies are generally noisy. If I use a Wall Wart or desk top supply I get lots of electronic noise. I did a lot of research and found some very low ripple noise Wall Wart/Desk top power supplies. I tried all of these with no success. I finally went to a Linear Power supply and got good results (similar to the PC power supply). My questions are what makes a PC supply so special? Why does it compare to a Linear Supply while others donít? PC supplies specs (ripple noise) are not that great. Does anyone have any ideas?
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Old 07-31-2017
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jonnyGURU jonnyGURU is offline
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The problem with wall warts or power bricks is that there is very limited space to install additional noise filtering inside their tiny housings.
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Old 08-02-2017
VitorOpressor VitorOpressor is offline
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I think the difference is that the linear source provides only one current. Already the switched source provides 5: 12V 5V 3.3V 5VSB and -12V. And the design of linear sources does not have the capacity to provide large powers with good efficiency.
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Old 08-20-2017
kileykupery kileykupery is offline
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Well thats false that you state pc power supply generally make noise.... it depends on the internal hardware as well. I have moderately good rig and a 440 watts power supply and it doesnt even seem to make a single noise while use..... Maintenance is the key.
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Old 08-20-2017
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You linked a 220W PSU.

Furthermore: "Maintenance is the key"?

What is that supposed to mean? We're not talking about fan noise.

Most noise from most desktop PSUs come from the switching frequency being within an audible frequency range. Also windings of coils, transformers, etc. that aren't wound absolutely perfectly (not typically possible in a mass production facility in China) will also vibrate at an audible frequency at certain loads.

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Old 10-21-2017
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PC power supplies live in a Faraday cage, while wall warts tend not to, and maybe this is the discriminating difference (covering it in aluminum foil might be a good experiment)

If the problem persists, I might be tempted to rewire the 12V to run on a twisted pair (or even coax) to reduce the radio transmission effectiveness of the unintentional 'antenna'

Of course here I am assuming radio noise, and am probably way off the mark.

Last edited by ashiekh; 10-21-2017 at 01:00 PM.
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Old 10-21-2017
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Most power bricks are wrapped in a metal shield within the plastic housing.
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Old 10-21-2017
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Good point; my bad
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