sourcing LED's

Discussion in 'The Projects Forum' started by Kane, Aug 9, 2010.

  1. Kane

    Thread Starter New Member

    Aug 5, 2010
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    What are the absolute brightest white and blue LED's and where can I order them?
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    What kind of leds are you looking for?
    High power?
    What viewing angle?
    Size?

    What part of the world are you?

    Bertus
     
  3. Kane

    Thread Starter New Member

    Aug 5, 2010
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    USA

    As wide a veiwing area as possible for aquarium lighting.

    Whatever power is required I guess. I'm willing to build accordingly.

    Probably the bigger the better.

    I'm building aquarium lights for freshwater tanks. The average size is 75-180 gallon (48" to 72" long by 18" to 24" wide and 24" depth) I want to have white for clear veiwing, blue for the added depth of color. I do not have plants.

    I'm reading up on how to build this. I have very good soldering skills. I've been getting on ok at learning how to calculate my power needs and how to assemble the components on the board and such but I have ZERO experience determining the brightness and quality of any given LED.

    Simply put, I want your eyes to melt when you look at one of my aquariums (no fish, just lots of beautiful minerals) The others I want no dark areas and well lit even in daytime.
     
  4. whale

    Active Member

    Dec 21, 2008
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  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Typically you look at the number of lumens an LED produces at a typical current level.
    I just put together an LED light for my reef tank. I used 12 Cree XP-G (cool white) and 12 Cree XR-E (royal blue) for my 30 gallon cube... It is VERY bright... I mean burn your eyes out bright. All mounted to a large heat sink and powered with 2 x Meanwell ELN-60-48D constant current dimmable drivers. LED's are great but they aren't cheap... $250 just in the LED's and power supplies.

    you would want something like this...
    http://www.rapidled.com/servlet/the-57/48-Ultra-Premium-LED/Detail
     
  6. marshallf3

    Well-Known Member

    Jul 26, 2010
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    The really good ones aren't cheap anywhere, sometimes using more of a slightly lesser part is more economical.

    You will also want to understand the relationship of the various units they use to express actual "brightness" as they're starting to throw in a third one now. Used to just be mcd, then came lumens, now some metric unit I can't quote from memory.

    They say "a pint's a pound the world around" but what if the pint came from an Imperial gallon?

    Kind of like some of my newer cars, half metric, half SAE and things like a 13mm will work on a 1/2" fastener but not the other way around. At least my 30 year old motorcycle is all metric but they used non-standard thread pitches on some of the fasteners. At least it's almost 100% restored now, mainly cosmetic stuff and replacing a few old rubber seals, I'm pretty much down to the paint and polishing stage on a full restoration.

    One of the most unusual bikes of the time, these things run for 200,000+ miles with only minimal maintenance and but a very few actual parts that eventually need replacing.

    http://motorcycle-specs.com/general/Honda-CX_500_Custom-1980.jpg

    Note the V orientation of the engine. When polished up like new they really draw attention. A lot of firsts on these bikes too:
    http://en.wikipedia.org/wiki/Honda_CX500

    500 cc, 50 horsepower, 10:1 compression, 10K RPM and they'll eat up most any new Harley aside from the very newest ones with fuel injection. I just enjoy the unique looks, the reliability, simplicity of service and the ease in which they ride.
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    While I would go with lumens, there are other factors involved. The biggest (after the intensity) is the beam dispersal, newer LEDs cheat by keeping the beam tight, which makes it look brighter than it is.

    Another comment, you mentioned melting eyes. With modern LEDs this is a real concern. Set them up where direct view is not possible, or some child will suffer injury. I remember as a kid shinning a flashlight directly into my eyeball, the flashlight pressed tightly against my face. With some LEDs permanent eye damage will result if a child does this. Just be aware.
     
  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Yes cree has a whole document on eye safety... It is serious.. Make sure that you read that too. I only looked at it for a few seconds and could see spots for a few hours after...
     
  9. bertus

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    Apr 5, 2008
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  10. Kane

    Thread Starter New Member

    Aug 5, 2010
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    Wow, that educypedia site is loaded with info. Great tip.

    I say melt the eyes only to impress the lighting I'd like to have. I went with some advice given to me by a freind and with 50 LED's connected using his source I'd bet a 40w lightbulb is brighter.

    My housings will be 3" recessed to prevent anyone from looking directly into the LED's. I took that into account from the beginning as I too have had my granddaughter dang near blind me with one of those 15 led flashlights. Saw spots for hours.

    That kit you link to, mcgver, is nice but I'm trying to stay away from those types of prices as I need several units.

    Just for the heck of it, do y'all think this might be what I could use or is this just crap?http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=300446262949&ssPageName=STRK:MEWAX:IT
     
  11. marshallf3

    Well-Known Member

    Jul 26, 2010
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    That eBay device looks legit, at least they mention name brand LEDs as the source. Over the years I've found many of the generic discrete LEDs sold on eBay not to put out anything near what they claim they are capable of. Anymore I just order from Mouser, that way I can look at actual spec sheets and they really aren't much more expensive in quantity.

    Of course these things have improved on an almost monthly basis. I bought some very tiny flashlights (1 cm dia x 4.5 cm long) from Harbor Freight a month ago and they're the brightest I've ever seen that run on three tiny coin cells - you don't even want to look anywhere near into the hot angle area of the beam. There's just one LED in the things and they'll shut down larger units with 15 or more LEDs without a contest.
     
  12. Kane

    Thread Starter New Member

    Aug 5, 2010
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    Can someone identify the "Q" components in this schematic? I cant find it in the sybols section.
     
  13. Kane

    Thread Starter New Member

    Aug 5, 2010
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    Sorry, got ahead of myself. They're V regulators as listed in the key.
     
  14. Papabravo

    Expert

    Feb 24, 2006
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    The Q Components are TIP102 Darlington Transistors. They were originally made by Texas Instruments. The "TIP" stands for TI Power. I Don't think they are voltage regulators in this circuit, but rather current regulators to set the LED brightness by adjusting the base current. Due to the Darlington configuration the gain is large and the adjustment is probably sensitive.
     
  15. Wendy

    Moderator

    Mar 24, 2008
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    Heh. Guess I should have put my name on that schematic. Looks like it will be making the rounds. Here is a clean copy.

    [​IMG]

    It came from this thread...

    Need help with simple LED grow light circuit: Cash reward

    Truth, I could do better. This design is a bit hot for my liking, as in generates a lot of heat. If you want to try something different let me know.
     
    Last edited: Aug 10, 2010
  16. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    Sure date it and plug allaboutcircuits.com under your name. :D
     
  17. Kane

    Thread Starter New Member

    Aug 5, 2010
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    If you have something better I'm very interested. I'd have given credit but the schematic came up in a Google image search.
     
  18. Kane

    Thread Starter New Member

    Aug 5, 2010
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    A bit more clarification is needed. On the TIP102's, as seen as hours on a clock; the 2 o' clock position is in, the 5 is out and the 9 is adjust, correct?
     
  19. Wendy

    Moderator

    Mar 24, 2008
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    The part with the hole is a metal tab. The tab is the back of the component. I threw them in there to make identifying the leads easier, it is one of the first things folks new to electronics have to learn.

    The tab is usually also the center lead, whatever the lead is. The case style is referred to as a TO220 case.
     
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