I found out that a computer PSU is an economic and convenient option for powering my signal conditioning circuit (SCU) which require +3.3V, +5V, +12V and -12V dc voltages for its working. My SCU reads millivolt signal from Wheatstone bridge circuit, amplifies and digitize the signal for re-transmission.
My Question is how good is a computer PSU for using it for such precision applications in terms of ripples, noise , EMI etc?
(I presume that a computer motherboard is more sensitive to power supply disturbances so a computer PSU will WORK FINE for my application )

 

I have just such a power supply as a bench supply. I've never seen any ripple or noise on the lines. Assuming you get a quality PS you should be OK. That's my opinion on the subject.

 

An ATX Form Factor PSU should do just fine. I doubt your power needs are very high. I would also suggest one of these in the best interest of keeping things clean and simple. Since you mention a -12 volt rail make sure your choice of PSU has the negative 12 volt output. Again make sure your choice of PSU meets your requirements as to available power which based on your description is low.

Ron

 

Filter the supply output by using series inductors for choking ripple presence, and extra capacitance after for smoother DC.
Computer supplies are very avoided in radios and high fidelity amplifiers and processors because of their switching frequencies leak and create noisy results. A toroidal transformer is far better as supply, but not saying your SPSU is noisy for your application.

 

I would also suggest one of these

Thank you very much for that suggestion!

 

Thank you very much for that suggestion!

Your welcome. It just may help as to easier and keeping things simple and neat.

Ron

 

Another option is to build a battery bank with several linear regulators and paralleled capacitors. Shielding the device in lead would also reject the majority of environmental interference.

The major downside is of course recharging and state of charge but that's a fair compromise for pure DC to begin with.

 

Thank you very much for that suggestion!

Make sure the breakout board you buy is compatible with your supply.

 

Since you're not concerned with having everything tiny in scale,
I would suggest that You use a Toroidal-Transformer,
and then simply add the other needed Windings that
the Transformer is not supplied with from the manufacturer.

There won't be any concerns about noise anywhere,
and it will be a little smaller than an ATX-Supply,
and most likely no Cooling-Fan needed.
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