PC ATX psu with +5V remote sense

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fjpompeo

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Hi folks,

I need to power a CNC cpu with a PC ATX smps but the TTL based cpu is one meter far from the PSU and the cable's voltage drop is more then 1 volt so need to remote sense +5Vdc output of the PC smps using TL494 IC. Will use only +5V(+-5% TTL LS tolerance) and -/+12V(that can reach -/+15V without problem).

Can you help me?

P.S. There is a lot of electrical noise inside a CNC latch electical panel!

Regards,

Fernando - PU2PLL
 

Here is the schematic of an ATX PSU: http://www.pavouk.comp.cz/hw/en_atxps.html

As you can see there is a feedback path from the +5V and +12v outputs - maybe
you could modify your supply and route them to your load instead. Use shielded
wires.
If the electrical noise level is very high you might need to build a differential
sense circuit of some kind, but you can try this simple modification to start with.

/Rambo
 

Well, can't you use the power cable wire of a gauge wide enough to eliminate this 1 Volt drops over the feeding wires?
You can use some special EMI filters or path-through capacitors to reduce the noise.
 

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