I have 2 equal power supplies and I try to control LED strips using arduino and n-channel mosfets. I've split the strips between the supplies, strip A + arduino is on one power supply, strip B is on the other.

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The problem is, that the other circuit is behaving randomly, and seems to be always open. I'm thinking if it's design problem. As arduino-mosfets for strip B are not on the same circuit (arduino is on different power supply, thus base is +5V on power supply 1 and it opens the circuit on supply 2). Is there a way to fix this without buying one big power supply (I cannot buy them here without waiting too long)?

Power supplies are the same: Meanwell LPV-100 (100W). LED strips use 2x72W, so there should be plenty of power. Mosfets are IRLB8721, from China. But they seem OK.

Thank you!

  • \$\begingroup\$ In my experience, 72 W of power consumption and a solderless breadboard is asking for trouble. The voltages and currents will be too high for such a build-up because you will have bad contacts in some places causing voltage drops and intermittent behavior. Also, include a proper schematic, you just show a "hookup" which doesn't show enough detail to check if everything is connected properly. So include the schematic and when that is considered to be OK, then use soldered connections for the LEDs and MOSFETs. \$\endgroup\$ – Bimpelrekkie Oct 17 at 13:30
  • \$\begingroup\$ You need to tie the grounds of the two power supplies together. \$\endgroup\$ – Dave Tweed Oct 17 at 13:42
  • \$\begingroup\$ I didn't use breadboard and soldered it myself. The wire sizes are sufficient. However, I'm not sure about my soldering skills as you mention it. I've checked the contacts. Hey, I'm sorry for the schematics, I'm new into this and don't think I can make proper one, I just found I can make something in Fritz. :) \$\endgroup\$ – mrr84 Oct 17 at 13:43
  • \$\begingroup\$ @DaveTweed will try, thank you! \$\endgroup\$ – mrr84 Oct 17 at 13:43

You need a common 0V between your two supplies. In your circuit there is no 0V reference between the arduino and the mosfets.

Add another wire between the two power supply 0V connections.

  • \$\begingroup\$ I've joined grounds of both power supplies, arduino power cable and also GND on arduino. Fixed, thank you!)) \$\endgroup\$ – mrr84 Oct 17 at 20:15

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