I have an LED driver:

LED driver

But I cannot understand the 12-40V @ 350mA and what I should be looking for to replace it with. The light gives no indication of voltage or draw so I'm trying to match this power supply and have no clue where to find one or do the math to figure out what a compatible driver would be.

Any help would be appreciated I'm in the US at 120V household.

  • 1
    The "light" that you refer to is an LED module, brick, or bulb type? Does it have any part/mfg numbers? The driver looks like a standard constant current LED driver so it will provide a constant 350mA to your load. The LED load can be 4.2W to 14W.
    – DigitalNinja
    Mar 17, 2016 at 22:15
  • The LED(s) define what the compatible power supply would be.
    – Nick Alexeev
    Mar 17, 2016 at 22:51
  • This is similar to the fixture at least in appearance. led-globebulbs.com/photo/… They have no markings on them and iI'm hesitant to pull out one of the other power supplies and use my multimeter as I'm not sure how to safely read the output with it. My biggest issue is these are installed all over my home with a 12inch opening in the ceiling and no markings on them what so ever. Would've been nice if the former owner would've left some clue...
    – Andrew
    Mar 18, 2016 at 13:12

1 Answer 1


As @digitalninja mentions, this is a constant current led driver. Unlike a variable current/constant voltage power supply, that attempts to keep the same voltage output regardless of the current pulled, a constant current supply will attempt to keep the same current, by varying the voltage.

It will, given a load like an led bulb, change the voltage until the current becomes 350mA. That could be a 24V 350mA led bulb/strip, or a 12V 350mA led bulb/strip, or whatever.

As such, you are looking for bulb that states it is that current draw within that voltage range.

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