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Can I use the computer ATX PSU to power electronics circuits

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vsmGuy

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Can I use the computer ATX PSU to power my electronics circuits ?

I see many using their ATX SMPS as PSUs, but I noticed that the output current is typically in range 1A to 20A. For example +12v is supplied at 10A

Most of the ICs we use have Icc (supply current) in 50mA range, for example, the popular MAX232 has Icc specified at 50mA

So if I were to connect 5v, 1A supply from ATX SMPS to supply MAX232, will it go bad ?

So how can I use the ATX SMPS to power my circuits ? Use a current limiting resistor ??
 

Re: Can I use the computer ATX PSU to power electronics circ

5V is still 5V - doesn't matter where it is comming from ..
If your 5V circuit draws 50mA, it will draw 50mA from a 50A (5V) power supply ..
If you want to be safe, use some sort of fuse, for example, 100mA-200mA on 50mA circuit .. similar effect you can achieve by using a 1Ω-2Ω/0.1W resitor ..

And, dont forget to connect pin 14 (green cable) to any BLACK cable to get it (the PSU) working .. see picture below ..

Regards,
IanP
 

Re: Can I use the computer ATX PSU to power electronics circ

To make things simple, you can think of the PSU as a constant voltage source, guaranteed to deliver the rated voltage upto the maximum rated current.

So simply, considering the 5V/10A supply, the PSU is rated to supply a constant 5v to ANY load which draws maximum 10A current.

However, if the load draws more than 10A from the PSU, then the behaviour is implementation defined. The PSU may blow a fuse, shutdown, etc...

So the PSU is good enough for the CMOS/TTL ICs - and don't worry about the ICs being "supplied" 10A of current ;)

A PSU SUPPLIES voltage and the load DRAWS the current. Be clear about this.

Got it ?
 

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    vsmGuy

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