LM317 SCHEMATIC HOW TO
LM317 SCHEMATIC FULL
LM317 SCHEMATIC SERIES

Internal pullup? That is only for input pinmode, it has no effect when using a pin as an output. This is my first time using the LM317 chipвЂ¦and trying to make a constant current circuit ever. It is regulating the current, and with no current draw, the voltage reaches the maximum it is capable of supplying.вЂќ вЂњOf course the output is high with no load connected. (just trying to take it all in and understand some of the last stuffвЂ¦ and see how it applies to my project and what specifically I need to changes things to.) No resistorвЂ¦ (I dont recall if I dialed down the AMPs or not? usually it at 1A or so)

LM317 SCHEMATIC HOW TO

Im not following on how to measure the currentвЂ¦ (sorry)вЂ¦ and I dont have any LARGE resistors like that around (no 1-2 watt fattys) just regular old SMD and through hole resistorsвЂ¦ of 1/8, 1/4, 1/2 wattвЂ¦etcвЂ¦Д¤.) Use a resistor when? you mean when вЂtestingвЂ™ the LED on my PSU? I just cranked the voltage down to +3.3vвЂ¦ and did a quick TAP on the leadsвЂ¦ to ensure it was working/is brightвЂ¦

LM317 SCHEMATIC FULL

Logic in the code should be the sameвЂ¦no? both common anode leds? I am using internal pull-up resistors on those pins.ДЈ.) I think your saying that the 1k resistor value between the transistor and Arduino pin is too high? lor is so I get more/full saturate of the gate, allowing the led to get full (constant) current? suggested value to use? I swap out the accent led for the LM317 board and 3W RGB LED STARвЂ¦ and its вЂonвЂ™ as soon as it is poweredвЂ¦ not bright eitherвЂ¦ but вЂonвЂ™вЂ¦ I put in the small, accent RGB ledвЂ¦ works as it 'shouldвЂ¦ The led should be OFF when powered onвЂ¦ (like its little, low powered, matching, common anode RGB led from Radioshack behaves) *however you saying the restвЂ¦ is sorta seems like what is happening? (no PWM, no color mixing)Дepending on the button press/eventвЂ¦ it will toggle/open that specific transistor only. Thanks for the replyвЂ¦ lets see if I can find some answers in there (theyвЂ™re thereвЂ¦ just over my head a bit)ДЎ.) yesвЂ¦ I will swap out the resistorвЂ¦ (silly mistake on my end not being more careful grabbing the resistors)Дў.) yesвЂ¦ this set up IS NOT intended to use more than 1 channel at a time. It is regulating the current, and with no current draw, the voltage reaches the maximum it is capable of supplying. Of course the output is high with no load connected. You did use a resistor when connecting to your 3.3V source, right? If not, you might fry the LED. So stick a 10 ohm 2W or better resistor in there and measure the voltage. If you want to see it operate without an LED, at 320mA a 10 ohm resistor will drop 3.2V, about what the LEDs will drop.

LM317 SCHEMATIC SERIES

In fact, that requires a Beta of 75, but the minimum rated beta for that transistor at 300mA is only 60.ДЄs for measuring the current in operation, connect a 0.1 or 0.01 ohm resistor in series and measure the voltage drop. A little variation in Beta could cause one or more transistor to dissipate a bit more power, and there isnвЂ™t much room for that in those tiny transistors. 4.3mA I BE for 320mA of I CE is not pushing it very hard into saturation. I would also drive those transistors a little harder. (so thats good) LOL :)ДЄdditionally - do you know that you cannot light all three at the same time? If you try, the one with the lowest V F will light and the rest will not or will be dim. Not sure how to try and measure the current output? Sounds ok with voltage drop across the whole board/components? (but makes me worries since thats WAY over the vF of the RGB led I'm using) Im measuring roughly +6.72v on the OUTPUT (I removed the RGB LED and metered the plug/wires ends to get this) Im measuring +7.4v at the INPUT (which is right. Where can I begin to troubleshoot this? (I'm hoping I dot need new boards for some reason?) RGB in use.the notoriously 'backwards' labeled DealExtreme 3W RGB star: it acts as if there is a short somewhere? and tested the LED to ensure it IS common anode, does work, (is super bright).and wasnt faulty there. I dont mean physically during assembly, but in design perhaps? or maybe I'm missing things elsewhere on how this works? (I had posted the schematic/board for review while designing it) I obviously have made an error somewhere. it would be a simple 'drop-in' replacement.(meaning just give the board the +7.4v directly from the battery source, and connect the 3 Arduino control/signal lines). after being assembled and the 3Watt RGB LED star also connected. Here are the files schematic, board layout and a pic of the assembled board.Д«efore these boards came, I was using a simple Common Anode RGB led from RadioShack (not a high powered led, simple 20mA spec.etc) I need some help troubleshooting an LM317 constant current circuit (pcb) that isnt working (as I believed it should).