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1N400x Diode Heat Sink

Discussion in 'General Electronics Discussion' started by CocaCola, Nov 3, 2012.

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  1. CocaCola

    CocaCola

    3,635
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    Apr 7, 2012
    So while working with a constant current LED driver I needed to pad the load for the driver to stabilize... I decided to do this with a string of 1N4004 diodes as they are cheap and I have them on hand...

    Anyway I probably could have got away with 5 diodes, but to make sure I was well into the drivers 'sweet' voltage range I went for 15... I had originally mounted them all on a perf board but I was not happy with how hot they were getting... Since they are in a forced air housing they probably would have been fine, but just to be safe I decided to redo them and mount them on an integrated heat sink... Again using what I had on hand, that being some 1/8" aluminum sheet stock... A few passes on the saw and a few holes later I had a heat sink...

    The diodes are slid into the snug fitting hole, and glued in place with a dab of super glue on each end... A nylon zip tie section was run between the rows as an isolator for the leads, it also helps keep the diodes centered if the glue fails...

    This diode unit is force fit between two fins on the existing units extruded heat sink, with a crimp or two on the fins to hold it in place...

    All in all I figured I would share the idea just in case anyone else needs a quick and dirty heat sink for multiple diodes, it works really well and it lowers the running temp quite a bit... I would post up temp numbers but my IR temp gauge is on loan this week :)
     

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    Last edited: Nov 3, 2012
  2. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    CC, it's clever, simple, effective and best of all it gave you some machine shop time. I imagine epoxy would work well too.

    Thanks for sharing,
    Chris
     
  3. Harald Kapp

    Harald Kapp Moderator Moderator

    11,522
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    Nov 17, 2011
    I second that. A neat job.

    Harald
     
  4. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    All wood shop time on this one I never seem to find much time to use the metal working tools... Table saw to whack the sheet stock to size, drill press to drill the holes, and a belt sander to knock down the edges...

    And yes epoxy would work as well (in the end the bond to the aluminum itself is nil), I just used super glue because it sets faster and wicks into the joint if the hole is a little over sized... At the end of the day with the leads bent over and pined by the nylon strip the glue isn't even needed as the diodes will remain centered on their own... And if that is the case a glob of thermal grease would be better but probably overkill...

    I mostly posted it hoping that is someone needs a diode heat sink they might consider just drilling holes in sheet stock like this, it's dead simple and honestly works pretty well...
     
    Last edited: Nov 4, 2012
  5. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    652
    May 8, 2012
    I liked it so much that I posted the link on one of my machinist groups. As we know shop and electronics often marry. By the way, I was surprised that the super glue adhered to the nylon tie wrap but I guess it did. ;)

    Chris
     
  6. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    The glue held enough for as long as it had to, in the end once all the leads are bent over and soldered it kinda holds it self together, even if all the glue failed nothing will really move all that much... That was the reasoning behind the staggered pattern with the isolator in the middle, believe it or not I kinda designed it to hold itself together if the glue failed because I know it will fail on the aluminum and even nylon...

    BTW, the guy has not come to pick up the light yet so I pulled it out of the box and let it run for an hour to test to see how cool it was running...

    With the original unsinked diodes on the perf board the diodes were very warm to the touch, pretty much on the the verge of being too hot to touch... With the heat sink in place and after a 1 hour test run today, there is hardly any noticeable rise in the temp of the heat sink overall, if you touch right over a diode it's warm to the touch but only marginal... Overall a very effective heat sink design for the purpose...
     
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