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I'm building a chicken coop opener - I've build my circuit (let's say arduino) with a DS3231 clock module and if functions as follows: My DS3231 will pull down its interrupt pin which is connected to my ATX supply (I-ARENA SERIES GPB-500S) enable wire (green). This will turn on my supply and power the arduino. So far so good. The arduino then do some funny stuff and eventually decide to either open or close the chicken coop door. So far this works and i successfully tested it. I want my circuit to be robust - so i chose a windshield motor because of conditions where i want to use it. The problem starts when my motor is running. I've measured that when the motor is spinning, it draws arduino 1 - 1,5 Amps @12V (Not bad, my atx supply should be very in range). I've limited the in-rush current using an 2 Ohm NTC thermistor, which helped start the motor and prevented my supply shutting down. But after few seconds (3 to 20) Of the motor and whole circuit doing just fine, the supply will shut down. I have no idea why because the current is in range... Is there some feature in my ATX that i'm not aware of? Is my supply not happy with inductive loads?

What i know:

  • The problem is not in my circuit - if i connect a lab bench supply it works fine.
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  • \$\begingroup\$ does your PSU run indefinetely powering a (let's say) 21 W auto bulb load? Does it need a dummy load on the 5 V output to be happy? \$\endgroup\$ – Neil_UK Mar 15 '20 at 10:06
  • \$\begingroup\$ @Neil_UK Just tested it, and it immediatelly shuts down after connecting a 21W auto bulb... \$\endgroup\$ – Kralik_011 Mar 15 '20 at 10:49
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    \$\begingroup\$ You seem to be left hanging so here is my two cents worth: ATX supplies are really designed for computer use only. I have read on several places where people try to use them standalone with little success (Of course you will not read about them when they work :-) It seems the manufacturers expect and test for a certain behavior on the outputs and if that is not the case they assume a fault and shut everything down. Thus the only thing you can try is to add a dummy load to the various outputs and hope it keeps working. Otherwise I am afraid you have to get yourself a standard supply. \$\endgroup\$ – Oldfart Mar 15 '20 at 19:20
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Well, It turned out that i haven't connected enough ground wires. After connecting almost every ground wire to my circuit, it started working!

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