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Cree Circuit Board Answered

Hi,I just want to know what a Cree Circuit Board is?Can this be used to connect a cree led to mains 220 volt AC? Here's a link-;=2&m;=2&r;=3&k;=1&t;=1&s;=58305&u;=26110

Question by Adarsh_tronix    |  last reply

High Power CREE LED circuit

I am trying to make two different circuits- one to operate 3 CREE XR red LEDS and 2 CREE XRE Blue LEDs. Can anyone point me in the right direction to solve this problem?? Thanks! Matty

Topic by walmatt23    |  last reply

Cree XB-D driver circuit

Hi Everyone,I would use following design with some modifications to be able to drive 3x3 Cree XB-D LEDs Green/Blue: Step 8 #4I would use 12V ATX computer PSU as voltage source.PWM source: Arduino nanoAttached picture show how I modified the design: 3x3 LED setupMy main concern, is it correct my calculation of LED currents: based on my understanding, 220mohm current sense resistor setup 2,272A current through FET. Based on Kirchhoff's current law, it will be 757mA for 1 LED.Is that correct?Any advise and suggestion would highly welcome.Thanks,Best Regards,Gyorgy

Topic by bernathg    |  last reply

hey can anyone give me a list of cree leds (lumens,volt,power etc. ?

I am looking for a cree led with a lumens of about 1000 lm(cool white).Pls suggest a site suitable for purchasing these items if you could,,

Question by Adarsh_tronix    |  last reply

High power LED brand recommendations?

I have an idea for an Arduino-controlled LED floor lamp and am interested in subjective information about the different brands of high power LEDs--pros and cons, the color and quality of the light, availability of heatsinks, mounting brackets, drivers, durability, price and so on.  Sparkfun sells Luxeon so it's tempting to just go with that, but I don't want to just go with that and find out something else was better.  I don't have a definite design yet just in the daydream stages, I want to be able to dim and brighten, turn individual LEDs on and off, be able to adjust the quality of light from warm to cool, I'm thinking white as a basis plus some RGB LEDs or other color leds to tweak the color, but the white light will do the heavy lifting, probably with some opaque white plastic or glass to mix and diffuse the light from all of the LEDs.  I found a few articles, but they're a few years old, or not exactly relevant (e.g. comparison of flashlights using these LEDs).

Topic by cdslashetc    |  last reply

Cree XL-M RGBW LED - recommended LED driver?

Hello I live in Australia and am new to the electronics world. I recently obtained a Cree XM-L RGBW LED 20mm 12W (image). I want to wire it up, so decided to browse the internet for wiring information. This has resulted in a multitude of questions and I haven't been able to find any answers.  From what I can gather, each LED runs @ 100% ~350 mA, up to a maximum of 1 A. Doing some research, it seems I should use an LED driver to ensure that a consistent voltage is maintained. I have some LM317T MOSFET/Voltage regulators coming in, but after some further reading, they can be inefficient. I read I can use an Arduino for PWM to help set different colours by varying the brightness of each LED. Can the Arduino also be used as a driver? Looking for a driver is where I'm stumped. I'm assuming I need a driver per LED. Does this mean I need 4 separate drivers or are 4 channel drivers available? I've seen some single-chip IC drivers and some larger (multiple component) drivers, which should I be looking for? I would have thought that drivers for this type of multiple LED would be easily found, but I'm stuck :) Maybe I'm searching for the wrong thing? I emailed Cree, but they simply gave me an email address for an Australian LED company that no longer exists (at least the domain is no longer active). So I thought the next best bet would be reaching out to users who may have dealt with these LEDs. Thanks!

Topic by hendrikse.alex    |  last reply

Ho do I pick an LED driver?

I bought a few cree XP-E LEDs and I'm very confused as to what drivers I should buy. This is my first electronic project so I'm a bit confused. I do know that for high powered LEDs, constant current is the only way to go but I have no idea how much I need. These are the LEDs I bought:

Question by iron_cupcakes    |  last reply


Http:// wonder if anyone can helpI want to make a bike light using CREE leds (*4) and have spotted the bflex (see here - - I was going to go for the UIB2 version) as it has battery monitoring facilities built into it. You set two voltage values v(low) and v(med). There's a connection on the board V(stat). S is the voltage from the battery.V(stat) = 0 if S is higher than v(med) => State 1V(stat) = 3.3V if S is between V(low) and V(med) => State 2V(stat) = alternates 0 and 3.3V between 0V and V(low) => State 3So I was thinking (of displaying this via 2 LEDs (green and amber))State 1 - green on, amber offState 2 - green off, amber onState 3 - alternating between green and amber.I was hoping to combine the LEDs into one bicolour LED. If anyone has any cunning plans or improvements they'd be appreciated.. whatever it end up with though it mustnt use up too much battery power.

Topic by EXM    |  last reply

Power LED Help

I'm looking to make some home lighting with LEDs, but I'm not sure how to regulate the current properly. I've really only used resistors up until now for led projects. I have a couple ATX pc power supplies, and I've used it to power an ebay led with no problems. I just touched the led directly to the 3.3v line and ground and it lit up fine. What I'm wondering is, is does the psu automatically adjust the current to what you need? Or is there something else I would need to worry about? (I figured it would be okay to power something off the 3.3V line if they were 3.7V leds, say several P4s)

Topic by opliko    |  last reply

Good place to get really good LEDs?

I have recently discovered that CREE has released some new XHP class LEDs awhile ago, and compared the the XML line that I have been a fan of, these ones seem to blow those out of the water. However, they are still somewhat $$$, although not too much. I would like to get my grubby evil hands on a few of the XHP70s, XHP50's, and XHP35s, but the "good" ones are out of stock on mouser and digikey. On amazon there are a few listings but they are overpriced and they do not list the binning or CRI of them. Any other reputable LED sellers? I want to see how well these would work to retrofit into either an existing el-cheapo XM-L flashlight as an upgrade, or a homemade lantern/portable floodlight. I basically want 80% or 90% CRI range and Neutral / warm white, preferably neutral. As you see I am not overly picky, but I want them for good usable indoor light quality. I have been impressed by the XML light output, but not the 6000K 70% CRI crap quality light like the ones I have produce. These LEDs are roughly twice as bright for the same physical size, and about ~30-50% more efficient. What I do want, however, is the highest binning available in it's class (aka the best ones.) Not for any particular reason (other than maybe bragging rights lol), but because I just can't bring myself to order comparatively less efficient ones with low/medium CRIs for pretty much the same basic price when I know damn good and well there are better ones for sale for only pennies more. Feels like I get cheated. :( Also if I order from mouser or digikey, I guess that means I would need to mount them to a star PCB myself, that might be a challenge. Since I do not have solder paste or a proper reflow oven, I prefer to not have to do that.

Question by -max-    |  last reply

black,red,green and white power cable supplying cree 3led bike light is broken. Answered

 I need help identifying which colour goes to which point.There are four points marked A G V B  on the PCB and i need to solder the 4 colours  onto their respective correct points.The cloured cables are coming from the battery and will be soldered on the cree LED pcb.

Question by teemandi    |  last reply

What buckpuck should I use with a 12 volt 5 amp/hour SLA battery with a Cree MC-E LED? Answered

First:  The Cree MC-E LED is rated at 350 milliamps but has a max voltage of 700 milliamps.  Does that mean I should get a 350 or 700 milliamp driver.   Two:  On ledsupply there are wired buckpucks with external dimming and potentiometers.  What is the difference between external dimming and what a potentiometer would do (lower the voltage and so dim the light)? Three:  On Deal Extreme it says driving voltage/current is 3.2V~3.5V, 350mA~700mA.  On ledsupply it says "12.8Vf - Typ. Forward Voltage @ 350mA and 13.6Vf - Typ. Forward Voltage @ 700mA?  What is the difference between driving and forward voltage/current?  What voltage and current comes out of the buckpuck? I am trying to make a bike light.  Thanks for the input -jacob

Question by Noblenutria    |  last reply

Battery powered arduino + high power leds?

I'm desperately trying to design an arduino circuit that can power each color of a high power cree MC-E color RGB led. What is the smallest dimension rechargeable battery I can use to accomplish this and have it run for a few hours? I'm desperate!

Question by SpiffyChee    |  last reply

I would like to make a on/off timer for 2 circuits, i would prefer one that comes on and goes off at a set time each day

I'm building a cree led lighting system and do to space restrictions would like a timer to fit in the fixture. I've read about the 555 timers and they could work, but i wont a timer that will come on for a set time each day ie be on from 5pm-11pm each day. Id be greatly appriciated if anyone could point me in the right direction. thanks in advance

Question by crx2ner    |  last reply

Which diagram would work best(want leds to work at their max potential, Help? Answered

Specs on all 3 leds  1 watt, red green blue Maximum forward voltage: 4 Vdc Maximum forward current: 350/ 700 mA (if you pick a diagram with a resistor please let me know what rating Ty)

Question by dougiedougworld    |  last reply

I need a diagram, please from a knowledgeable person, can any one make me a diagram for leds to sync to music please? Answered

I need a diagram. i have parts and will pick up more if needed, please specify what voltages, ohms, needed as well if heat sinks are needed,  Parts i have. One of each of the following leds. surface mount LED is mounted on a 0.80" diameter aluminum disk which serves as a heatsink and provides solder spots to simplify connection. Cree X Lamp 7090,  1 WATT GREEN ULTRA-ULTRA BRIGHT LED 45/ 73 Lumens @ 350/ 700 mA 100 degree viewing angle Maximum forward voltage: 4 Vdc Maximum forward current: 350/ 700 mA Cree XLamp 7090,  1 WATT BLUE ULTRA-ULTRA BRIGHT LED 19/ 31 Lumens @ 350/ 700 mA 100 degree viewing angle Maximum forward voltage: 4 Vdc Maximum forward current: 350/ 700 mA Cree XLamp(TM) 7090, 1 WATT RED ULTRA-ULTRA BRIGHT LED 34/ 55 Lumens @ 350/ 700 mA 100 degree viewing angle Maximum forward voltage: 4 Vdc Maximum forward current: 350/ 700 mA I have 3  Tip31 NPN TRANSISTOR, 3A 80V TO-220 I have One 12' CABLE, 3.5 MM STEREO PLUGS BOTH ENDS i have one  Stereo plug splitter ( so i can listen to music while lights are going) I have 100' of red and 100' of black 24Ga hook up wire i also have, solder, solder gun, wire snips/strippers, access to resistors and power supplies, volt meter/ohm meter, and other tools I would like it to be a wall plug system using an adapter The leds were about $10 per so please give me real diagrams, dont waste my time or money. I will be double checking the diagram, and checking to make sure all math is correct, will i need resistors and what type, will i need heat sinks even tho the leds already have 1 built in, ?

Question by dougiedougworld    |  last reply

I have 3 led's, would the diagram work the way i want,?

 i would like the 3 leds to work as follows, left speaker left led, right speaker right led, and central led will be off of both speakers, i am quite sorry for my ignorance, i am very new to this and it is a gift for a friend, so i really want to know as much as i can before  i start blowing things up :),  each led is 1 watt and works best at 700 ma from what i understand, but can work between 350-700, so i am hoping 600 ma is fine, i have a wall plug adapter with switch for 3-12v, i will be using a v meter to test these numbers are accurate, it says current 600 ma., in my previous posts i was recommended to buy a CCR, but i haven't the  time to order this,  will this power source eliminate the need? i also have picked up quality heat sinks, and arctic silver, i am not the best at electronics, i do have a relative who works with HVolt  batterys and knows some about electronics, he works at TDI in nj, hes busy so cant ask him much, i am hoping this to be my last post, please help a guy out, thank you all for your support and positive and helpful comments first image without resistors second with

Question by dougiedougworld    |  last reply

Do you always need a buckpuck for high powered LEDs? Answered

I want to power a Cree MC-E LED with a 12 volt 5 amp/h SLA battery.  Most of the time you have to use a buckpuck (an LED Driver).  Do you always have to use a buckpuck?  If I have a 12 volt battery and a 12 volt LED like the CREE MC-E, then I don't need a driver, right? Thanks Jacob

Question by Noblenutria    |  last reply

Wanting to design a cree led powered dock rechargeable torch running on 18650 cells

Hi all, I had an idea the other day that it would be very useful to have a powerful torch in my van that is kept charging in a dock all the time (as required at least) when the engine is running.I know I can get similar torches that charge via a USB cable, and that I could plug the cable into a cigarette lighter socket etc, but what I would like to do is as follows:Power from a 12v (ignition switched) source in vehicle, to a charging dock.Torch must be powered by 18650 lithium-ion cells (2 ideally).Torch would run a cree (or cree style) powerful LED chip/diode (maybe up to 10w arbitrary power).Torch does not need to have a wire plugged into it, but can be simply placed into the dock after use in order to resume charging. The connector for charging is not important but likely a jackplug type arrangement, or else spring terminals.Housing will be 3D printed, and using a lens from an existing torch (probably).So mostly I'm happy about making and designing this, except that I'm not certain about what setup (either the circuit design if bespoke or what off the shelf module etc) I should use for taking 12v to charge 2x 18650 cells in situ.I have got small USB charging modules already, and I have things like voltage boosters/reducers, and tons of electronic components, but the USB charge module is no use for using with a 12v supply etc, so I'm not sure how to best address this part of the project.If anyone has suggestions on good ways to accomplish this I'd be really grateful, thanks!

Topic by Mr Joshua    |  last reply

What driver would I need to run 36 Cree xm-l leds for an offroad light bar?

I'm new to diy led and would like to know where I can find a driver suitable to run 36 xm-l leds.  I would assume that my Voltage could spike up to 16V on the charging system.  I would like a simple on/off as I have a svt raptor with factory upfitter switches. 

Question by Jambat1    |  last reply

LEDs : Require urgent HELP about LEDs. Answered

Could somebody please answer me that using an array of 135pcs of 5mm LEDs that produce 12000mcd each be better than using 3pcs of Cree MC-E for a motorcycle headlight. will the 5mm LEDs produce more light (lumens) than the MC-Es. If yes then will the distance of the beam of light produced by the 5mm LEDs be the same as the distance of the beam produced by the Cree MC-E?  By the distance of the beam I mean how much far can the beam produced by an array of LED light up the road. Please answer somebody answer me quickly I need urgent help. I will be very greatful to youll

Question by Jayvis Vineet Gonsalves    |  last reply

Is there a simple way to power both 6 and 12 volt devices from a 12 volt battery? Answered

I wired up my bicycle with a 12 volt battery.  The problem is, I have a Cree MC-E led which requires between 5 and 10 volts with a buckpuck.  One person suggested resistors to drop twelve volts to nine but that would waste too much electricity.  Is there a simple way to cut the voltage in half to six volts which would not loose power in the conversion process.   Cutting the power to 6 volts would be best because there are devices aside from the light requiring 6 volts which I want to install. 

Question by Noblenutria    |  last reply

How can I salvage LEDs that are welded to metal heat sink? Answered

I have a light fixture that used to be an street lamp, and the 350mA 240V constant current ballast failed. The LEDs appear to be welded directly to thin insulated metal sheets which as somehow bonded to the large metal heatsinks. I think the LEDs are Cree XR-C's, and there are 6 of them on each module, and there are I think 6 modules in total. I have some ideas, but how would I get the LEDs off the modules, if they are even worth saving at all? They are according to CREE they produce 78lm @ 2W, and are a pathetic 39 lm/watt. If I can get them off the aluminum heatsink easily enough, I might be able to use them for prototyping purposes so I do not kill $$$ XM-L LEDs, and do not kill 3mm white LEDs either, since I tend to kill those quite fast too by overdriving them or too much voltage. It is amazing to think how far technology has come, that XML led sitting next to the module outputs more than double the light, with less 20% less power!!! I have always thought that LED technology still has a WAY to go before becoming practical enough to justify the higher costs, but if a company has installed this Piece of Sh*t light fixture back when these LEDs were 'state of the art' than I wonder when metal halides go obsolete!

Question by -max-    |  last reply

LED Dimmer circuit needed

LED dimmer circuit please suggest me a good one,my LED is CREE XML LED voltage ratings is 3-3.5V and current ratings is 0.7-3A.Input should be 5Volts. It should have a variable resistor with switching function.ON/Off potentiometer. Your early response is welcomed!.?

Question by Faizan Hamayun    |  last reply

Is there a way to power this led?

So I bought this torchlight (Supwildfire 50000lm) it says is a Cree XML T6 LED with a total of 15 LED (not sure cause no Cree branding but from what it looks like it is indeed XML LED). So the funny thing is I burnt an unknown controller on the LED driver by inserting the wrong power adapter. But the torchlight still works by twisting the head to on/off, just cant on/off, brightness control using the button and battery monitor. Now I was wondering is there a way I can buy a led driver or what to look for that supports this many LEDs and still have the functionality of brightness control etc? as i saw there are LED drivers design for DIY Cree LED torchlight (Example: See pic with blue title bar) but I wasn't sure will it be enough to power this many LEDs or will the driver die because of overcurrent.From what I know the unknown controller is supposed to control LED brightness, on/off, and monitor battery level and the display. From what I measure using my multimeter the LED is getting 2.6V if the LED is on, if it is not connected to the board, the board is outputting 3.6V. Also using diode mode I'm getting 2.320V on the LED. As for Amps, I think it is not outputting right as I only measure 0.44A (440mA), or maybe it could be that it is on low brightness.Battery: x4 18650 3.7v li-ion in parallelThere's only 1 9926a mosfet on the negative side x4 R100 SMD resistor in parallel on the positive side

Question by ongjonathan97    |  last reply

where can i get a CRE LED DRIVER CHIP?

I am interested in getting driver chips for CREE LED LAMPS. I would like to get hi power  source of 6000 --- 8000 lumen s LED lamp for using as a projection lamp. I would like any novel ideas or suggestions.

Question by fxaugustine    |  last reply

simulate lightning Answered

Hey, i would like to simulate a lightning storm in my aquariun, by using 6 cree xre led's and some sort of micro controller to control the flash, i need to figure out the multi flash and random flash and flash druation, any ideas would be welcome. also what controllers out there can handle  say between 500-700 milliamps,

Question by tinman11    |  last reply

How to reduce LED drain on battery?

I have a Cree Q5 LED, I established the typical forward voltage is 3.7V and the maximum current is 1000mA. I'm confused as to how I reduce the current, I want it to run at 350mA, I know this is possible, I'm just not sure on how to go about doing this. Can anyone point out how I do this. Thank you.

Question by jakespikey    |  last reply

Wiring high power LEDs and need some direction.

Hello all, I am currently trying to design a product, we'll simply call it a light, that requires 6, maybe 7 extremely bright LEDs. I'd like to keep it running off a 3v battery. The LEDs I would like to use are made by Cree (XP-E2) or something similar. The specs can be found on this page: My question is, will I even be able  to fully power 6 of these things off 3V or even 6V(I'd rather keep it to 3V)? If so, how long can I expect the battery life to be? I've never had any experience with these high power LEDs before, but all of the other SMD LEDS only light to ~40 lumens. I'd really like to make this work, or find a similar alternative. Thanks in advance.

Question by bodezia    |  last reply

Thermal epoxy or Thermal grease and bolts?

I am mounting 15 Cree LEDs to get an old overhead projector to work as a video projector. the only thing I am wondering is whether thermal epoxy is better to use than thermal grease with bolts and nuts attached to a heatsink. Do both have the same heat dissipation? What I am trying to do is still use the LEDs for use with other projects in case i need them for something else.

Topic by KT Gadget    |  last reply

Can I fit a 10W heatsink in a zippo? Answered

I want to put a cree XM-L LED in an old zippo, and I want to know if anyone knows how to fit a big heatsink in the top part of a zippo lighter, not in the base, and preferably able to buy everything from a hardware store, not ordered online.  Also, does anyone know how to anodize aluminum for added heat dissipation?

Question by jduffy54    |  last reply

LED Mountain Bike Light

I'm designing a home made LED mountain bike light.  I Intend to use three CREE XPG 3UP stars which have three individual cree XPG LEDs mounted in series on a MCPCB star shaped board. Each individual LED when driven at 1500mA (the intended max current) will have a forward voltage of 3.5V. Therefore each 3UP MCPCB star will have a forward voltage of 10.5V when driven at 1500mA. If I wire the three MCPCB's in parallel the current drawn from the battery will be 4500mA - correct? I was planning to buy an 11.1V / 6000mAh rechargable lithium-ion battery pack.  The battery pack will be connected to the LED's via a b2Flex LED driver that limits the max current to 1500mA but can be set to run at 350mA, 700mA, 1000mA and 1500mA max by programming the b2Flex driver. The light will probably be set to max current for short periods of riding but spend most time at 1000mA.  Does anyone see any problems with the slight voltage overdrive (i.e 11.1V from battery vs. 10.5V that he LED's will theoretically require) I'd really appreciate any feedback on this. Cheers Todd.

Topic by trhnelson1970    |  last reply

LED light with different LED, run at differen currents

Hi All i need some help, I am looking to build a light with a string of 2 led's 1 string will be cree royal blue (XPE) running at 700mA, which should use about 3 volts per LED 2 string will be cree Cool white (XML) running at 1500mA which should use about 3 volts per LED Each string will have 13 LED's in it, I actually need to run 2 sets of these. I would like run a set of a single power supply. so the Blue and white would run in Parralal with each other, and the 13 LEDs would be in seriers. So it would be string 1 Blue (3x13) = 39 Volts at 700mA 2 White (3/13) = 39 Volts at 1500mA Then a repeat of the above if possible off the same power supply. to add to this i woudl like to be able to dim each sting. This dimming function can be manaul, and would only reaaly occur a few times, while I adjust teh light setting to meet my requirments. So with this all said, can it be done, which I am sure is the case. then how do I do it.? Many thanks Damon

Topic by wukkie  

LED drivers to match lights?

Hi All I have looked at a bunch of DIY LED bike/headlamp instr. and would like to give them a try, with my own spin. I just need a litle guidence an some bulbs to match drivers, I don't want to use the BuckPack systems. I will be powering these with a 14.8v or 18.5v li-ion battery system Here is the bulb I think I would like to use.;=item5ae0e1766d Now there are different idea's for drivers, with this on can I run 3 of the bulbs on one driver or should I build three drivers? Same for these two drivers. This is the driver mode for the last one. Thanks for all your help and the time you all put into this great site!!!

Question by vallka  

Could I use this LED driver to drive a laser diode? Answered

I've been trying to construct a blue laser for my friend using KipKay's instructions, but I don't have a good driver for it. If I add an extra current limiting resistor at the end of it, will this ( LED driver provide a good regulated output for my laser? If not what else could I use to regulate the output?

Question by Shagglepuff    |  last reply

Which Lasers Flashlight on Everbuying should i buy?


Question by stella1740    |  last reply

Hey Guys,I need some help making a project for school

It needs to have at least 1 555 Timer within it. I was thinking of building a jacobs ladder with a 555 timer or if i could get it working perhaps a sonic pulse generator. Want something interesting and that won't take more then 7 weeks to build. Would it be possible to make a Cree Light and mod it to turn off after X amount of time? I'm just struggling to find idea's as our projects must be able to run off a 12V Battery or less and we cannot make anything dangerous. IE Rocket Launch Controller etc.... Thanks

Question by bcurko    |  last reply

19v to 12v, 16.7a continuous in as small a space as possible.

I have a 19v source from an AC/DC adapter, i need to output a 12v source at up to 200w continuous in as small of a physical space as possible. I have a tight spot i need to fit it. I have approx. 1"x1"x5" of space available. I'd prefer if all inputs and outputs were on the same side (one of the short sides). The 12v output needs to have low ripple, it will be powering ATX compliant circuit boards. If anyone knows of a product that already does this, i'm all for just buying something. I did a little searching, but everything that works is too big. Thanks,Sean Crees

Topic by sean.crees    |  last reply

Need pre wired high power leds

I am in need of a pre wired High Power Led board. Something like a Cree XR-E Q2 Emitter. I would like to find a supplier that I could buy pre built/ wired boards (plug and play) to install in a small lighting package. Ideally I would like to find a pre built light that I could incorporate into my project. I need a high output 12v white light, that I can make a reverse light out of. I am hoping to market the product so a supplier over a retail option would be best. Any help you could give would be greatly appreciated Thanks in advance  

Topic by returnforservice  

5 mm led's 8 LUMENS PER WATT!?!?!? [answered] Answered

Well i was thinking, 5mm LED's take about 1/10 of a watt, correct?  and from this calculator found out Cree 5mm led's are .806 lumen's. i assume they are 1 tenth of a watt. well, my calculator states they are 8 lumen's per watt (if i could run them at a watt.)  i figure they are 1/10 of a watt because because this 500 led light makes takes about 50W as in the video and led's give less than a lumen of light. so far, it seems leds just last long and emit blueish light. is incandescent light better? with 20 lumens per watt from halogen?

Question by -max-    |  last reply

How to pick an LED driver?

Say I have 3 LEDs in series that have a Max Forward Voltage of 6v and an operating current of 1000mA. I could get a driver like a buck puck, say the 3021-D-E-1000mA BuckPuck. It has an input voltage of 5 - 32v, and let's say I give it the full 32v, so how does that not end up burning out my LEDs? My actual goal is to have 3 strings of 6 Cree XP-e LEDs connected to 3 Drivers. But I can't quite figure out how to properly size the driver. I know it puts out a constant current, and the voltage fluctuates -- what is there to determine which one to get so I don't end up pushing too much voltage? Or am I misunderstanding something about how the voltage will fluctuate? Sorry for the noobishness, this is my first real electronics project.

Question by z0dii    |  last reply

Idea: Smart LED front door light with PIR detector and light sensor

Hello to all. I searched the forums for the project I plan to do, but found no real answer. Here is the idea: I want to have a front door light using CREE high power LEDs that would: - stay off during the day - turn on at 10% current level when night falls - ramp up the current gradually to 100% current when a movement is detected, stay at 100% for a preselected amount of time, then return back to 10%. This would make a very efficient front door light. I have some experience making headlamps using buckpucks and power LEDs (thanks to dan from this site), but I have no idea on how to make the "gradually changing" current driver for that project. I guess it would involve a microcontroller of some sort. Has anyone some insights on this ? Thanks for reading, Mike, Switzerland

Question by 4fontaines    |  last reply

Can you recommend an LED to me? Answered

I'm looking for a white LED that is 5mm or smaller.  My problem is that there is such a great selection of LED's on the internet, I can't determine which of the many options are best!  Here's my criteria: *5mm or smaller (cannot have a heatsink) *white (preferably without a bluish tint; a pure white) *wide viewing angle *bright (high mcd) † this is the order of priority for the criteria as well I understand that there's a trade off between viewing angle and mcd; ideally I would like to find a happy medium. Through the research I've done, I've heard names like Nichia GS, Cree 503D, and Jeled.  I'm not sure if these have a large enough viewing angle but regardless I wasn't able to find anywhere to buy these.  It would be great if you could include a link to a place to buy your suggested LED or at least insure that they are available for sale before posting a suggestion, after all it's not useful for me to know the name of a product I can't obtain.  As always, Thank you!

Question by cdubnbird    |  last reply

Can I use arduino to control my high-powered bicycle headlight?

I'm in the midst of building a new high-power led headlight for my bicycle (i.e. Ive ordered a new battery and a bunch of hardware, led's and a driver).  My question for the community is whether or not an arduino unit could be used to control functions or modes of the light.  I have built alot of lights and know a decent amount about electronics but I have zero experience with arduino and programing.  I am using this buck driver ( with a triple cree xp-g led and a 14.4v lithium battery.  Ideally I would like a single button to cycle through 5 modes: off, low, high, F-U idiot driver, and strobe.  If anyone knows what kind of stuff I would need to buy(i.e. controller, switch,etc...), if the stuff would interface with this driver, and how I would go about programming the thing I would much appreciate it. Thank you, Patrick

Question by phish814    |  last reply

3Watt LED Recessed Ceiling Downlight - 12 Volt Question

I'm new to the world of LEDs, but have recently completed a DYI using Cree XR-E as eaves lighting outside my steel building.  Comtemplating doing the same on my personal residence and was considering the 3W 3 LED ceiling downlight ac85-265 under the soffits of my home.  These can be found in great abundance on EBAY for as low at $3.99 per unit (China made  ).  My question is this: All the units I've looked at have attached LED resistors.  However, I only want to use a 12 Volt power supply (meanwell) placing all units in series.  What do I do with the resistors attached to the fixtures (LEDs)?  Can I remove the LED resistors and attach 12 volt power supply directly to the 3 W fixture?  Elementary question from an elementary low voltage guy. thanks for your responses in advance. 

Question by soonerbliss1    |  last reply

Joule robber - a better joule thief....

I had a look at some of our 'ibles for the famous Joule Thief circuit. While checking a few of the creations and checking their performance I noticed a massive flaw: Only LED's with very low power consumptions can be used. After some trial and error I was able to create a slightly modified version that not only lights white and blue 5mm LED's but also the very powerful Cree Led's - the later would require a suitable transistor to handle the load. I only used a salvaged BC556 transistor, so the LED starts working at around 0.5V, brightness is adjustable within certain limits to cater for the battery state. So instead of using a limited circuit that basically just doubles the input voltage with the focus of extreme low power consumption, my circuit is aimed on single cell battery lamps that might need more power. Using a very low voltage transistor with minimal losses would still provide a power source for batteries that are under 0.5V, while using a bigger transistor like Tip142 or 2N3055 and a modified transformer can drive a CFL lamp from two AA batteries, single cell if you don't mind a warm transistor. Biggest improvement however is that I don't use a toroid core, which makes winding so much easier :) I am not too good in drawing circuits and prefer the direct solder method for my prototypes but if there interest I would take the time to make some pics and draw a circuit for an Instructable. But with so many similar circuits already out there I wanted to get some feedback first.

Topic by Downunder35m    |  last reply

LED Wiring, Over Amp Burnout? Answered

Hi everyone, hope someone can help? I just started playing around with some LED lights, trying to make a really bright Flounder light that can last at least 6-8 hours on the supplied battery. I was told if I used a "step-down", I wouldn't need resistors, (since the step-down does this in an essence), which I haven't, But the step-down keeps burning up? Here's the set-up I've been playing with... - 18vdc (power drill) battery. (unknown amps). - Step-down driver.... input 8vdc - 36vdc, output 1.5vdc - 36vdc - 3w LED Cree :                            ~ Reverse Voltage: 5.0 V                           ~ DC Forward Voltage: Typical: 3.8V Max: 4.2 VD                           ~ DC Forward Current: 700mA                           ~ Luminous Intensity: 170-190lm                                                           I use a volt meter to tune the Driver to a constant 4vdc to drive the LED. And the driver burns up and then the bulb after about 5 minutes. I was told I needed to add Ceramic Resistors, between the driver and battery, and between the driver and LED. (But what size?) I was also told I don't need extra resistors because of the driver? Which is Right? Or should I just add resistors between the battery and LED and do away with the Driver completely? Also, what is meant by "Reverse Voltage"? I have a 6vdc battery with a 4.5 amp capacity. But I want to use the 18vdc battery longer use, time wise. This is why I have the Driver, when 1 battery deletes, hook up the other one. I'd like to put 3 - 3w (180L) LED bulbs together, and run them off the 6vdc and/or the 18vdc battery so the LED's will last for at least 6-8 hours on 1 charge. I want to use either the 6vdc and/or the 18vdc battery because they are lightweight. I could go with 1w LED's so long as I can get the brightness needed to light up a distance of about 12' underwater to see a Flounder, and get 6-8 hours usage. Any help would be appreciated.

Question by Atomizer    |  last reply

HELP, I NEED / desperately want A SUPER BRIGHT FLASHLIGHT for camping / boy-scouts [answered]

Inappropriate Incomplete Spam first thing first, i want absolutely the BRIGHTEST flashlight i can my hands on! how many lumen's should i shoot for (to impress others)? 100, 270, 350, 600, 900, 1500, 3600, 5000+ (5000 Lm i pretty sure is overkill)? i have an led flashlight i got for 12$ and is advertised to be over 600 Lm but I'm pretty sure its maximum is 70Lm. (it seems to be slightly brighter than the 9 LED tactical flashlight i had) but I'm not sure. i have no light meter. the LED itself is (as advertised) is CREE (i don't believe that either but again, I'm not sure).   i would like to make portable HID flashlight. my plans are to: BUY: 6V LANTERN HID KIT (BULBS) HID BALLAST 12V BATTERY (I"m not sure where i could find a suitable 12-15V 35W [or more] battery that will fit nice and snug in the lantern with room for the ballast. the battery should last almost a week with some moderate use.) i think a drill battery would work. i will take the original light out and replace it with the HID. then, i will need to find a place for the slim ballast [but where???] . then,i need to find a battery (i think a 12V drill battery should work [will a 14.4V drill battery with the case off fit in the modified 6V lantern flashlight? if so, where can i buy a affordable and well suited 12V-16V battery?] if there isn't any small, powerful (and preferably cheap), battery in existence? [4 by 4 by 2 array of AA rechargeable batteries seems promising and so does 6^2 by 2 array seem promising. 6 by 6 by 2 AAA] will the ballast and lamp work with less power (6W-34W)? is there a simple and small ballast circuit schematic i can follow? i never found one. so i assume no. :-( also is the 5000K neutral white, warm or cool? (i think it is the closest to neutral white with a VARY slight blueish tint) i think i got a grasb on this and i want 6000K (i want something led white but still bright and useful enough to easly see what i'm doing on campouts)

Question by -max-    |  last reply