5v supply through Extender module...what's the max draw in current?

I’m playing around with the new RGB LED strips that arrived today, and I’ve got a full reel, which is 5m, and according to this:


the strips can draw up to 2A per meter, which means that a reel could (with all LEDs on full white) draw as much as 10A (eep!)

My question is this…if I power my mainboard (currently testing on the Cerbuino Bee) with a wall wart, is the supply coming directly from the wall wart via the power jack, or is it going through the mCu first?

And either way, what is the max amount of current I can safely draw from the 5v supply on an extender?

I’m assuming that the “right” way to wire this up is to get a beefy enough power supply, and hook that up to the RGB LED strip separately from the board entirely, and just connect the grounds from the power supply and the extender, and run the SPI signals to the LED strip from the extender, and the +5v from the power supply to the LED strip.

Does that sound right? I don’t want to burn up any of my beautiful blinkies, nor kill a mainboard out of ignorance. :slight_smile:

I believe the DP module current limit is “over 800ma” with an external power source, and the SP is the USB target of 500ma.

The external power is going through the DP power supply which has the current limit.

You definetly need external power supplier for led stripes driver…

May be this can help you:

Thanks, Mike. I was thinking about getting a beefier wall wart and running it through this:


But alas, it turns out that the breadboard power supply only supports a max of 1.5A. While that’s twice what I can get out of the USB Client DP (and presumably the power jack on the Cerbuino Bee), it’s not nearly enough to reliably power the entire strip.

It may finally be time for me to crank out the planned PC PSU to bench PSU conversion project I’ve been putting off for so long…whoever thought I’d need 10 amps of DC power? :smiley:

@ devhammer - Do you know who sells the 5mt stripes of this leds in Europe ?

@ devhammer - do you actually need to light them all at once or can you light just a few at a time but very quickly like with a multiplexed array? I suspect you could get by with the later.

I don’t, sorry. I got mine through @ ransomhall, perhaps he might know of a supplier.

Yes, but I don’t want to just “get by” I want ALL my blinkies lit!!! :slight_smile:

I’m in the process of converting a PC power supply over for use as a bench supply, which should give me more than enough amperage to power the full strip. PSU is rated for 22A at 5v. Hopefully should be plenty of power.

Alrighty… Although I wouldn’t call that just “getting by”. It’s a pretty standard way of doing it. Requires a lot less power and in most cases the human eye can’t tell the difference. It also makes a really cool demo. My zombie gun “site” is a multiplexed array that has one LED lit at a time. When I’m telling the crowd about it, I briefly explain how it works and then I put a video cam on it and project it up. Due to the frame rates, you can then see the individual LEDs getting their turn. That wasn’t planned the first time but it was such a hit that it’s in the presentation intentionally now. :slight_smile:

I was just joking about the getting by part. Truth be told, I’m just scared to death of frying a mainboard, so I figured that this is a good route to ensure I have plenty of power available. Plus, it’ll be handy to have the bench power supply available for other projects, should I need it.

Given that the wall wart I have (switchable 3v-12v) only supplies 1A, and the LED strips can draw up to 2A per meter, it just seemed a safer bet to me to go over what’s needed. That way, if I goof up in the software, I don’t burn anything up (hopefully).

Does that make more sense now?

Oh, I understand. I have a PS3 power supply that I did the same thing with. I just didn’t want you bringing down the power grid when you got your next order of blinkies in the mail :wink:

Well, I’m about to find out if my FrankenPSU will actually supply as much current as I had hoped. Got it all wired up and tested for 5v and 3.3v (I wasn’t thinking and cut the 12v wires back at the PCB…d’oh!). Now it’s time to hook up the blinkies and see what happens. :slight_smile:

Forgot to follow up…FrankenPSU works a treat. Lights up all 320 LEDs in the 2 reels nice and bright!

I’ll make sure to get some video from MADExpo and post. :slight_smile:

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Can’t wait to see someone wrap themselves in those and do some dancin’. Disco Inferno, baby!!!

@ devhammer - DP just released their version of a FrankenPSU breakout. It’s got some nice features. I may be ready to upgrade my hack job :wink:


the DP board has 1.25 amp fuses on all of the voltages. Not enough current for lots of LEDs.

Yup. Not even close, alas. I guess they use the fuses to limit current (and limit potential damage from overcurrent), but what a shame to waste the potential of an ATX PSU.

why not swap out the fuses with something beefier?

Couldn’t one use the Molex/SATA power connectors for light strips and other high (5/12) voltage devices and then this device for the FEZ?

I think at some point there might be an issue with the traces on the PCB?