G+_Dan Molseed Posted June 23, 2016 Share Posted June 23, 2016 Episode 213 Fr. Robert Ballecer, SJ talked about connecting Ws2812 LEDs and arduino separately with 5v power. Did I miss where this was covered? Maybe a later episode? Link to comment Share on other sites More sharing options...
G+_Dan Molseed Posted June 23, 2016 Author Share Posted June 23, 2016 Around 20:35 into show. Link to comment Share on other sites More sharing options...
G+_Branden Snyder Posted June 23, 2016 Share Posted June 23, 2016 A.) I use a power supply like this one. https://www.amazon.com/gp/product/B018TEAPRQ/ B.) Use one of the output +/- pairs for the Arduino and the second for the LED's. They are simply in parallel so you can do this many other ways. C.) If you have issues with the voltage dropping and the Arduino randomly freaks out, try putting a 1000uF (microfarad) capacitor in parallel with the LED's, as close to the LED's as possible. This will buffer any large changes in current draw (ie. when you turn a bunch of pixels on at the same time) and help to minimize the voltage drop. Just to share my experience, but not recommended... I have many Arduino's to replace the ones I break lol :P I have successfully powered up to 48 pixels of ws2812's from my Arduino uno of a USB wall charger. I ran one of the sample sketches and got distracted by something else (squirrel?!). It must've ran for a couple hours and it didn't burn out the Arduino. They were not on full brightness, so I can't say exactly how much power they really pulled from the Arduino. I don't recommend running any pixels from the logic board. The risks are pretty high that you'll burn it out or shorten the life of the board. But for playing around, learning the ws2812 module, testing your Arduino code, etc... Link to comment Share on other sites More sharing options...
G+_Tyler Pearson Posted June 23, 2016 Share Posted June 23, 2016 Ive seen mention of using a 1000uf capacitor before in other projects and on a best practices from Adafeuit i believe. But its always been for a full strip of ws2812b. Is there a way to determine or a calculation for using a smaller capacitor for less leds say 50-100 leds instead of a full 300 led strip. So for 50-100 leds maybe only a capacitor in the 200-350 range or something. Link to comment Share on other sites More sharing options...
G+_Branden Snyder Posted June 23, 2016 Share Posted June 23, 2016 The Adafruit site gives a range of 100-1000uF. I'm not aware of any calculation to determine the "correct" size capacitor. Over-sizing the capacitor is not a problem so you could make a habit of always using a 1000uF cap. I believe there is a direct correlation between these variables, aka Less pixels = Less current change possibility = Less voltage variation Also, Meanwell makes good quality psu's with good load regulation. The specs on the LRS-100-5 that I linked above say that a 50% to 100% to 50% load changing 120 times per second it will stay within 297mv of rated output. Thus, between 4.7 and 5.3 volts under a changing load. http://www.meanwell.com/mw_search/lrs-100/LRS-100-5-rpt.pdf It may even work without a capacitor. Most of my projects don't use one. Try it out and see if it works :) Link to comment Share on other sites More sharing options...
G+_Dan Molseed Posted June 24, 2016 Author Share Posted June 24, 2016 I want to use a small 6v lead acid battery (about 5 Ah) to power both the arduino and the LEDs using this regulator (http://www.readytoflyquads.com/rtf-1v-17v-adjustable-voltage-regulator) to get down to 5v. I am better off running 2 power lines from the regulator to the arduino and the LEDs separately? Instead of running power from the regulator to arduino and then out from arduino to the LEDs? Or did Fr. Robert mean you should have 2 separate power supplies? One for arduino and a separate for LEDs? I'm guessing it depends on the power draw of the LEDs, aka how many you strand together. I will have about 168 LEDs in my project. And plan on running 2 power lines out of the regulator. One to the arduino and another to the LEDs. Is it any advantage to use two of the regulators, or should I just use 1 of them? Link to comment Share on other sites More sharing options...
G+_Tyler Pearson Posted June 24, 2016 Share Posted June 24, 2016 1 regulator should be fine. 168 Leds would draw too much current through the arduino and should be run like you intended with 2 sets of +/- from the output of the regulator. One set to the lights and a other to the arduino. Also make sure that you connect one of the ground leads from the Leds to the arduino as well. So the led strip should have a +/- going to the regulator and a data pin and ground going to the arduino. Then the arduino should have +/- from the regulator seperatly. You may want to add 1000uf capacitors as well between the power and ground at the led strip and arduino? I myself am still new but this is how I plan to set mine up unless i here otherwise. I e also heard about adding a resistor on the data pin line as well for best practice. Link to comment Share on other sites More sharing options...
G+_Branden Snyder Posted June 24, 2016 Share Posted June 24, 2016 I preface this post with "To the best of my knowledge..." lol. Correct me if I'm wrong In a 5V DC circuit, the "-" line is the same as ground. So you don't need to run a second ground from the led's to the Arduino, as long as you use the same 5V source. If you run the Arduino from a USB cable but the led's from the battery regulator, then you are using 2 different sources and you MUST connect grounds. I get this confused with AC circuits when you have a hot / neutral / ground combo. The ground is only a safeguard, or a "reference ground" (that's how GFI's know if you're hair drying fell into the bath tub lol) Link to comment Share on other sites More sharing options...
G+_Branden Snyder Posted June 24, 2016 Share Posted June 24, 2016 Regarding the 300-500 Ohm resistor on the data line, I don't use one.. But your mileage may vary Link to comment Share on other sites More sharing options...
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