david1701 Posted December 2, 2008 Share Posted December 2, 2008 hey guys i'm thinking of making something along the ideas of this http://brainerror.net/texts/howto/macroring/ but scaled up and crossed with this http://www.diyphotography.net/studio...ld-a-ringlight so i intend on using very powerful led's (these http://www.rapidonline.com/Electroni...s/78767/kw/led are the brightest i can acquire) and mounting them in 4 alternating rings of 9 (or possibly non alternating rings of 18 - bot colours not just one) which will give 36 (or 72) LED's which should be fairly bright each ring is to be wired as 9 (or 18) parallel leds each with a series resistor (about 140 ohm) with the rings in parallel to each other and switched individually (as i have no idea about brightness) just wondering if any wiser heads had any thoughts to add David (just a thought i use a dslr so its not gonna be a silly looking huge ring on a little compact cam ) Quote Link to comment Share on other sites More sharing options...
david1701 Posted December 2, 2008 Author Share Posted December 2, 2008 had some feedback from photography guys about potential brightness and they have doubts anyone know of a way of doing this without using heatsinks which would make it v ungainly Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted December 2, 2008 Share Posted December 2, 2008 http://brainerror.net/texts/howto/macroring/http://www.diyphotography.net/studio...ld-a-ringlight http://www.rapidonline.com/Electroni...s/78767/kw/led Neither the second or third links function as you desire. They both bring up error pages. ------------- requested project not found sorry, Looks like there is no project like you are looking for. ------------ and --------------------- Looking for something on Rapidonline.com? The page you are attempting to access does not exist. You may have followed an outdated link -------------------- Quote Link to comment Share on other sites More sharing options...
sotal Posted December 2, 2008 Share Posted December 2, 2008 I think these are what the links should have been: http://www.rapidonline.com/Electronic-Comp...Ds/78767/kw/led http://www.diyphotography.net/studio-light...ild-a-ringlight Quote Link to comment Share on other sites More sharing options...
david1701 Posted December 2, 2008 Author Share Posted December 2, 2008 yep those are the links, so sorry they were duds Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted December 3, 2008 Share Posted December 3, 2008 Assuming you are using 36 LEDs, and each one is 30mA, you will need a PSU that will kick out (0.03*36)=1.08A. Nothing too hard there. Rather than having a resistor for each LED, I would have a single resistor for each bank of 9. You can also avoid the need for a heatsink if you use a PSU with an output voltage close to that of the forward voltage of the LEDs (from the technical info...3.3v) So, assuming you use a 5v supply (closest one that should be easily available) and running 9 in parallel, you will need (5-3.3)/(0.03*9)=6.3 ohms for each ring of 9. The power dissipated by the resistor will be (5-3.3)*(0.03*9)=0.459 Watts. So use a 6ish ohm resistor rated at 1/2W and all should be peachy - you won't need a heatsink to dissipate this amount of power. Or, if you can get one, use a supply that kicks out 3.3v and don't use a resistor! (By contrast, if you use a 12v supply, the resistor will be dissipating over 2W - you'll need a heatsink then...especially if you think you will be running 4 of the things.) Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted December 3, 2008 Share Posted December 3, 2008 Another thought just occurred to me - if you put each ring of 9 LEDs in series and use a 30v PSU - no resistors needed. Quote Link to comment Share on other sites More sharing options...
pete3000 Posted December 3, 2008 Share Posted December 3, 2008 I would have a look on e-bay and save yourself a small fortune in time and money . Search for led ufo light. or led camping light. I pay around a fiver runs off 4AA alkaline batteries. (don't use high power nicads, no current limit, burns them out quickly) these come with 24/48/36 leds and are really useful when camping or repairing as they have a low profile and can be stuck with a magnet, hung up or on a screw. Pete Quote Link to comment Share on other sites More sharing options...
david1701 Posted December 6, 2008 Author Share Posted December 6, 2008 cheers for the help guys, but i'm gonna abandon this one as i have talked to photography guys and they doubt i will get enough light for anything but macro work, and i don't really do macro work. But thanks for all the info, David Quote Link to comment Share on other sites More sharing options...
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