MCE bike light - Updated with Images

I've been lurking here on CPF for a while and decided to post the beginnings of a 3x MCE bike light I'm building.

Started with 1" x 3" section of copper core board from Bergquist. Etched the board to drive the LEDs in a 3s4p configuration (or is it called 4p3s?). I also ground away the dielectric to make a direct solder connection b/t the LED and copper core. My back of the envelope calculations suggest that, with 10W conduction through an area the size of the MCE pad, even a 3mil dielectric results in about a 20C differential, though I could have made a mistake.

Before mounting LEDs:


After reflow, before soldering legs:


With Ledil LM1 "diffused" optics:


And finally a beamshot comparison with a 20W halogen on the left (1.7A at 12V) and the 3x MCE light driven at ~20W (2A at 9.9V). Identical camera settings for both shots.


Cheers,
Brent

Re: MCE bike light

can't see your pics?

Re: MCE bike light

I think I have to wait for attachment privileges.

Re: MCE bike light

No you have to upload pictures on some picture server and than paste links to them...

Re: MCE bike light

You have to upload your pictures at a image hoster like imageshack.us. I am really interested in seeing this pics.

BTW we have a subforum for bike lighting here at cpf. If you like you can ask a mod to move it there.

And... :welcome:

Hi Brent

I like your idea of mounting the LED, but I have one concern, It looks to me like you are using a standard thick plastic cored circuit board. This has no thermal path to remove heat from the LED to a heatsink.

I would consider using AA epoxy to glue the LED direct to a piece of Alloy and connect them using wires.

Beamshots look nice - which supplier did you use for the optics?

Cheers
Nick

blesbok,

I have been meaning to ask if you used copper MCPCB, or is it just a plain PCB with copper cladding? If it is copper cored MCPCB, then is it cheap and easy to get in small quantities? Can it be purchased with the convenience of an online shop? How is the quality? I was curious, but I was on a quick break from studying for exams and I just did not look up the company Bergquist. Maybe after classes today, I can find more details.

Thank you for sharing your idea. If you are using what I think you are using, and you can order small quantities for a decent price, then I will be extremely happy! :twothumbs I am afraid of the qualities of some aluminum MCPCB stars, so I usually bypass them and solder or epoxy emitters directly. Atleast with this stuff, you can etch all the way through the top cladding and the PCB and solder or epoxy the MC-E slug (electrically isolated anyway) directly to the thick copper. If this stuff is of supreme quality, then I may not have to etch through past the PCB material.

Cheers,
-Tony

blesbok said:

Started with 1" x 3" section of copper core board from Bergquist.

Click to expand...

Guys, I think he's fairly clear here (emphasis and underline mine).

Yes, the board has a solid copper core, ~0.040in with a 3mil dielectric, and I think 2oz copper. I called to request a sample and a few days later a local rep showed up with two 18" x 24" panels, one aluminum and one copper. The rep assumed I was producing these lights in quantity.

The board in the picture above was processed by covering the entire board in a layer of kapton tape and using a razor to cut away sections to be etched. I ground away the dielectric with a dremel. Having to do this manually takes away the appeal of typical PCB processing techniques. I would be really interested to know if someone could confirm or refute my rough calculations for the temperature drop across the dielectric.

I doubt I'll use the Al panel at all and probably only a small portion of the copper panel. Since I got them for free, I don't really want any money. I'd be glad to give away small sections for the cost of shipping or a small donation towards the MS Society. Just send me a PM if interested.

Here's the link btw: http://www.bergquistcompany.com/thermal_substrates.cfm


-Brent

Had to ride today so I put together a simple, but tank like housing. Power for the moment is three 700mA buck pucks in parallel. Even at only 2.1A I never wanted more light.