G+_Jason Kirk Posted March 22, 2016 Share Posted March 22, 2016 I'm trying to power a string of 300 rgb leds and the ardrino that runs them. The power will be split to the ardrino, and to the leds so that the ardrino isn't powering the leds. I've got a bunch of old power adapters with output voltages higher then the 5 volts I can use for the task. How do I convert some volts into amps to power everything? Link to comment Share on other sites More sharing options...
G+_Arcturus Lancaster Posted March 22, 2016 Share Posted March 22, 2016 You would have to build / buy DC DC converter or just get a 5A 5v PSU. It is a lot of power to try and convert and your random adapter might not give enough current. Link to comment Share on other sites More sharing options...
G+_Scott W Posted March 22, 2016 Share Posted March 22, 2016 Are the RGB LED's 5v or higher? And what are the specs of the power supply you intend to use? Link to comment Share on other sites More sharing options...
G+_Jason Kirk Posted March 23, 2016 Author Share Posted March 23, 2016 Cool, I guess you do post on here a lot. LOL I'm not as worried about volts as I am about having enough amps and after seeing your last podcast about amps/volts being like ocean waves, I was wondering if I could get a power supply that outputs at a higher voltage and convert the excess into extra amps that my LEDs will need. I actually bought half a dozen of the cheap voltage limiting devices you've mentioned in the past from ready to fly quads so I'm covered there. I'm not sure how they effect amps though. Do they stay the same, do the volts get turned into amps, etc? And how is it related to what you posted? Backing up a bit, I help out at a high school maker space and I saw a video on how to make LED lit indoor clouds on sparkfun https://www.adafruit.com/products/658 and thought that would be a attention grabber for the kids and relatively cheapish. So I'm trying to build a prototype to get them interested. To help keep costs down, I was trying to reuse old power supplies from defunct routers, etc though I'm realizing something like https://www.adafruit.com/products/658 would be better in several ways. Right now I'm powering the LEDS with a table power supply and the ardruino with a USB power adapter. Before I worry about a long term power supply though, I need to make sure I have the controller locked down. Thanks for the help. Link to comment Share on other sites More sharing options...
G+_Scott W Posted March 23, 2016 Share Posted March 23, 2016 The LED string will pull the amount of power it needs from your power supply depending on how bright they are. You just need to make sure your power supply has enough amps to power the LED strip. The average 1 meter 300 light LED strip will need apx 18amps per meter at full bright. If you are just going to be blinking the lights and running a pattern, the 10a power supply you link to would work, but I would find a step down that matches the power supply output. Link to comment Share on other sites More sharing options...
G+_Jason Kirk Posted March 23, 2016 Author Share Posted March 23, 2016 Here's the LED strip I got https://www.sparkfun.com/products/12026. Looks like you were right on the money. 60 per meter, equaling 300 LEDs in all with each of the 3 colors taking 20 mA so 18amps in all I'd like to aim for worse case, but it doesn't even look like the power supply I mentioned would take care of this. I assume the worse case when set at max brightness is that the lights wouldn't be as bright as they could, or would the power supply heat up? I suppose I could wire in another power supply farther down the line, but this project is already getting to be more than I planned. If I don't disconnect the power leads for the two half strips so both power supplies feed into the same line, would it cause any problems? I'm not sure what you mean by a step down. Link to comment Share on other sites More sharing options...
G+_Jason Kirk Posted March 23, 2016 Author Share Posted March 23, 2016 Mud must be thicker where you come from. LOL. I should have the voltage regulator covered, I got the ones Padre mentioned several times in the past from Read to Fly quads. It's the amps that are the problem. Using the voltage regulator on the power supply you mentioned, wouldn't trade out volts for more amps, would it? Even if not, 3 of them would be cheaper than two of the ones I mentioned and I can get it from Amazon so free shipping. Could I wire then all in at the end and have them combine their amps or would something start to melt? Link to comment Share on other sites More sharing options...
G+_Jason Kirk Posted March 23, 2016 Author Share Posted March 23, 2016 Thanks, that is a lot more helpful than the one I found. Though I'm not sure how they solved the amps problem yet. But anyway, thanks for your help. Link to comment Share on other sites More sharing options...
G+_Arcturus Lancaster Posted March 23, 2016 Share Posted March 23, 2016 Rgb means 20 ma per colour so 60ma per rgb led at max. So 60ma x 300. 18A at max power. Depends on what you do with it if you pull full draw Link to comment Share on other sites More sharing options...
G+_Jason Kirk Posted March 23, 2016 Author Share Posted March 23, 2016 Yep, that's how I figure it. And for a second there I thought I did the math wrong and I just needed a third as much power as I thought. And the spec sheet shows 20mA per color, not 18.5. Link to comment Share on other sites More sharing options...
G+_Jason Kirk Posted March 23, 2016 Author Share Posted March 23, 2016 Yeah, all three equals white drawing 20mA each so 18 amps in all. I can of course dial all of them down equally to make it less bright. Link to comment Share on other sites More sharing options...
G+_Jason Kirk Posted March 24, 2016 Author Share Posted March 24, 2016 True, unless the cloud was maxed for lighting purposes. I'm just surprised that powering a single strand at max can be problematic with how LEDs are suppose to use so much less power. Link to comment Share on other sites More sharing options...
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