evanski Posted June 7, 2009 Share Posted June 7, 2009 Note to self... 1. DO NOT connect the power supply directly to LED without the driver in between...it drastically limits the life-span of the LED. My best estimate is several microseconds before failure. Newbie electronics mistake. 2. DO NOT look at the LEDS directly. I am seeing spots almost 30 minutes later. Thanks to Cdelicath and Evilc66 for inspiration and help! E Link to comment
Yamato Posted June 7, 2009 Share Posted June 7, 2009 Note to self... 1. DO NOT connect the power supply directly to LED without the driver in between...it drastically limits the life-span of the LED. My best estimate is several microseconds before failure. Newbie electronics mistake. 2. DO NOT look at the LEDS directly. I am seeing spots almost 30 minutes later. Thanks to Cdelicath and Evilc66 for inspiration and help! E That was just wnat I was wondering. Why do I need a driver when my power supply says the current it outputs is less than that of my LED. Say my led can handle 1a, and my PS says it outputs .7a doesn't that mean it should be safe??? Yes, I am a noob at this, please inform. thanks. Link to comment
cptbjorn Posted June 7, 2009 Share Posted June 7, 2009 If you have a multimeter and can measure exactly how much current is actually flowing and it is less than the rating of the power supply, then it is safe. Otherwise it is not. For any given voltage put across an LED it draws a certain amount of current, so while the power supply can source up to .7A safely the LED can still draw more than that, potentially overheating, burning out the led, blowing a fuse in the supply, and also potentially working just how you want. All depends on how the power supply is set up (specifically its output impedance). Also one possible failure scenario is it working perfectly until you go on vacation and it starts a fire. Link to comment
evanski Posted June 7, 2009 Share Posted June 7, 2009 If you have a multimeter and can measure exactly how much current is actually flowing and it is less than the rating of the power supply, then it is safe. Otherwise it is not. For any given voltage put across an LED it draws a certain amount of current, so while the power supply can source up to .7A safely the LED can still draw more than that, potentially overheating, burning out the led, blowing a fuse in the supply, and also potentially working just how you want. All depends on how the power supply is set up (specifically its output impedance). Also one possible failure scenario is it working perfectly until you go on vacation and it starts a fire. Roger that. What I CAN tell you is that 12V and 3A was too much. A flash and then nothing else... Link to comment
Yamato Posted June 8, 2009 Share Posted June 8, 2009 Roger that. What I CAN tell you is that 12V and 3A was too much. A flash and then nothing else... Okay, I know it doesn't make a difference bc I made the mistake already, but it was not 12Vs but 5 V and not 3A but .7 A... None the less, I hope I didn't bust my LEDs...damn rookie mistakes...just too impatient. Link to comment
evilc66 Posted June 9, 2009 Share Posted June 9, 2009 Yamato, remember that your 0.7A power supply is also 5v, which is enough to kill the LED in the short term. Your test shouldn't have caused any major issues, but don't do it again. DC power supplies are constant voltage, so the LED would see 5v, no matter what. A constant current driver would keep the voltage down to what the LED wants, regardless of the what the voltage on the power supply is. It's a saftely precaution so your array will live a long and happy life. Link to comment
SpankythePyro Posted June 10, 2009 Share Posted June 10, 2009 I've gone through a couple pages here but could we get a diagram? I'm very interested in the rebel stars and leds I saw earlier... I'd like to experiment when I have money and as I am a hand-ons person I probably won't fully understand this till I have something in front of me. Link to comment
Yamato Posted June 10, 2009 Share Posted June 10, 2009 Yamato, remember that your 0.7A power supply is also 5v, which is enough to kill the LED in the short term. Your test shouldn't have caused any major issues, but don't do it again. DC power supplies are constant voltage, so the LED would see 5v, no matter what. A constant current driver would keep the voltage down to what the LED wants, regardless of the what the voltage on the power supply is. It's a saftely precaution so your array will live a long and happy life. Duly noted Evil, thanks for the heads up. Again, rookie mistake...I got to control myself. Just can't wait to see this sucker in action...have to be patient and wait for the drivers to come in. If you have a chance, I would love to read your comments on my LED array...check out my thread...thanks. Link to comment
cdelicath Posted June 10, 2009 Author Share Posted June 10, 2009 My LED pico is up for sale $80.00 This will include the tank, filter and LED pendant. "You will need a way to hang the pendant" I can make the unit mount on the tank for a extra $10 instead of hanging. I will also sell the rock, coral and sand for a extra $40 If you want the ATO unit with it add $15 "no pump, just ATO" It would cost over $150 to build this unit new. more info here: http://www.nano-reef.com/forums/index.php?showtopic=180447 and here: http://www.nano-reef.com/forums/index.php?showtopic=180485 Link to comment
Yamato Posted June 10, 2009 Share Posted June 10, 2009 why you selling the pico? You bored of it? Link to comment
cdelicath Posted June 10, 2009 Author Share Posted June 10, 2009 why you selling the pico? You bored of it? got a new one that is a bit bigger. It's a secret that 2 Link to comment
Yamato Posted June 11, 2009 Share Posted June 11, 2009 You doing another LED project? if I didn't order all that stuff fomr my light, I might have asked for the LED set up Link to comment
cdelicath Posted June 11, 2009 Author Share Posted June 11, 2009 You doing another LED project? if I didn't order all that stuff fomr my light, I might have asked for the LED set up Yeah I will have LED's on the new tank. Link to comment
Yamato Posted June 20, 2009 Share Posted June 20, 2009 More questions about Drivers, wondering if you can help me out again. My hook up through a NR member did not work out. Now I am stuck with no drivers or powersupply. I am not too keen on spending more money on the light since I was only able to do it within budget when I had a deal on the drivers and PS...but now its not going to work out...anyway...sigh. Just so I can get this straight, if I have a 12V .7a PS, a driver would lower the voltage to the needs of my LED? If I have two LEDs set up in series, the driver would lower the voltage output to 7.4 (3.7 +3.7v) thus not allowing more than .7a of current running through my LED? Is this correct? thanks Link to comment
evilc66 Posted June 20, 2009 Share Posted June 20, 2009 Kind of. The driver will vary the voltage required by the LEDs, but it will also limit the current to a fixed point. The power supply is not responsible, or capable of that. Link to comment
Yamato Posted June 20, 2009 Share Posted June 20, 2009 then the next question I pose is this: would I not be able to eliminate the need for a driver if I was able to get my hands on a PS that puts out: 3.7 v and .7a? I would just wire the lights in Parallel, thus deliverying 3.7v to each LED. Would I be doing something bad to the Amps? Less amps per LED if I wire in parallel. If I had 5LEds in Parallel, would this be too much of a load for my PS? thanks Link to comment
evilc66 Posted June 20, 2009 Share Posted June 20, 2009 DC power supplies are not constant current. Just because they say they are rated for XXXmA, doesn't mean that they can't suply more, and the LEDs will draw more if they are allowed. This is the whole reason we use drivers. They are a constant current source that will prevent you from cooking the LEDs. To make it simple... DO NOT RUN LEDS DIRECTLY FROM A DC POWER SUPPLY WITHOUT ANY FORM OF CURRENT LIMITING DEVICE. You can't cheap out on this. If you do it right now, the setup will last for many years. If you cheap out, it may not last past the end of the week. Link to comment
Yamato Posted June 20, 2009 Share Posted June 20, 2009 DO NOT RUN LEDS DIRECTLY FROM A DC POWER SUPPLY WITHOUT ANY FORM OF CURRENT LIMITING DEVICE. I am so stubborn and cheap. Sorry for having you guys to spell it out for me. I am frustrated because I didn't get the drivers and need to blow my budget inorder to get this project off the ground. Thanks a million. Okay, so drivers are needed to ensure good LED life. As for power supply, can any old adaptor with the right voltage output and amp good...I have been eyeballing a surplus store with some adaptors (black ones...u know...) thanks again Link to comment
evilc66 Posted June 20, 2009 Share Posted June 20, 2009 As long as the voltage is more than the forward voltage of the LEDs, plus 2v for the Buckpuck, you will be fine. Get a power supply that has more current capacity than you need. They will typically run cooler then, plus you also have a bit of room to add other things if you need. Link to comment
plantarms Posted October 17, 2009 Share Posted October 17, 2009 this is such an awesome pico and led build! it's a bummer that you're getting rid of it. i think i am going to be building an led pendant fairly soo, but i've got a few questions. does the lighting spread from the pendant you built cover the whole pico or is it more spotlighted? also where did you get your heatsink? Link to comment
cdelicath Posted October 17, 2009 Author Share Posted October 17, 2009 It covert the whole thing very well. The heatsink was a old AMD heatsink I had laying around. Link to comment
plantarms Posted October 17, 2009 Share Posted October 17, 2009 after building this is there anything you would've done differently? possibly using two buckpucks with dimmers, more or less led's, no fan mount, anything else? Link to comment
cdelicath Posted October 17, 2009 Author Share Posted October 17, 2009 Actualy I would have used less leds because I kept that unit at half power to keep my coral happy. It was too much light. The coral was growing like crazy but the coloring was dull and nothing would fully open. After dimming the unit everything got much bigger and more colorful. 1W 2B is more then enough IMO. Link to comment
plantarms Posted October 17, 2009 Share Posted October 17, 2009 thanks for the tips, i think i'm going to to this with a smaller heat sink and less led's on my 2.7 gallon pico. i also read in the thread that you and evil were working on a timed dimming system to simulate sunrise and sunset and i saw your ordered some of the parts, did you ever get it to work with arduino? if so i am very interested, i'm currently at school for business and computer programming Link to comment
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