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Fasttech 532 heatsinking.

Marco Polo

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I received my five-dollar 532 modules from Fasttech shortly before Christmas. One died immediately. Or rather, the crystals died. The 808nm diode works fine. The other two seem OK, more or less.

Turns out they will need heatsinking, but not the sort I expected. One component on the board, a D882 transistor, gets very hot, very fast. It gets hot even faster when you pot-mod these and turn up the current. The D882 is the only component that gets hot. Everything else stays cool.

Note that even if I don't pot-mod the laser, the D882 still gets hot, just not quite as fast. It will still need heatsinking.

I have some 4-gauge solid copper wire that I can use to make a heatsink, really thick stuff. I figure I can cut off a 1/2" or so and file/sand it into a block that will fit in the host, and then thermal epoxy it onto the D882. The idea I have is shown in the photo below. The D882 is marked with the red arrow. The yellow rectangle is the approximate size and location of the heatsink, fit as best I can given the constraints. The blue arrow shows how the blue resistor would be moved (bent) out of the way.

What are your thoughts on that; that's pretty much how one would go about making a custom component heatsink, isn't it? The only real issue will be to make sure nothing gets shorted out, but I can use some lacquer or "liquid electrical tape" to cover up exposed metal / component pins. Solid idea?

 
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You could also try cold forging it by
beating it with a hammer and a flat piece
of steel. It will be enlarged by the
forging, so you might want to start with
something a little thinner such as 8 or
10AWG. The better way would be to find a
friend that has a rolling mill. A large
vise might also be able to crush it between
2 pieces of flat steel.
 

Pman

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Never bothered to heat sink any of my Fasttech modules but can certainly verify that those points do get hot very fast.
That sounds like a good idea for a small heat sink for basically no $ since you already have the wire. You could certainly purchase copper that is already flat or buy a pack of the copper washers that Harbor freight cells and cut a piece off (thought of that since I have so many of them). They or any hardware store may have better options of course. Obviously you want to do it as cheap as possible and the wire is a good idea. Shouldn't be an issue moving the resistor. Only thing is you obviously need to keep it tucked in or it could rub in your host. I always put dabs of epoxy where the corners of the driver meet the module so the diode pins aren't the only thing hoding the driver in place. Potential issue if you solder a spring on the end from the torque of screwing down a battery.
I'm quite surprised one of the modules failed immediately. Can't remember if that ever happened to me with well over 100 of them. In the beginning I ruined a couple by trying to set the mA with a metal screwdriver while the units were powered.
Also, Fasttech is currently out of both the 5V (my favorite) and 3V versions. About a week ago I ordered (5) 5V versions and they could only send 4. They were hoping to get more in a couple weeks but no promises on that. I asked them to ship a 3V one in place a couple days ago and they sent me an email this morning saying that they are actually out of the 3V ones also.
Apparently I had purchased the last ones but at least they had automatically shipped my 4. Told them they can just ship the missing one when they come in so I will get a message when more are in stock.
In my opinion, they are the best deal out there for modules as apparently they don't bin them as they arrive set at various mA which of course I set to .43A. Think that when the new ones arrive I'll try a heat sink and test the temps before and after as I don't currently have any 532nm ones that aren't already in builds.
If you have an empty pen host they make a great upgrade to the usual cheap pens. You can epoxy the upper portion to the cap and as long as the lower section is tight to itself and the host you will have a focus able 532nm with usually enough output to light a green headed match from 4-6" away (the module will not have threads to focus any closer) if it outputs over 50mW.
Drives me crazy when I see younger members spending $60 on a claimed 200mW module. I've purchased a couple and if they actually work it is more likely it will be not far above 100mW and they look the same as these. Personally I think they are just being set at a higher mA and binned. For that amount of $ you could buy 10 of these and it's very likely a few will hit that same mark.

Just thought of something. Have any old computer heat sinks with fins that are all copper? I've got a ton of heat sinks but I think they are all aluminum. I should look through my "stuff" and see what I can come up with. Remember, what ever you use it really only has to be flat on one side. I'll think about this more...
 

Pman

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Hmmmm I think I just found a good solution. I have a bunch of 15% stay-silv braze. Just brazing rod. Have any around?
 

djQUAN

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The D882 is a pass transistor of the linear driver. All the unused battery voltage times the diode current is dissipated by it as heat.
 

Pman

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I received (5) 532nm Fasttech 5V modules last week and decided this time to heatsink that D882 this time on all of them. What I did was cut small pieces of 15% brazing rod, mixed up some Arctic Alumina and put them on. If you like this idea and could use a piece I could certainly send you a stick MP. It works great as it is the flat kind instead of round.

As a side note, after setting them to .43A on my variable DC power supply they were 74, 75, 75, 95 and 126mW peak. Usually I would get 2 out of 5 to hit over 100mW but 74mW of 532nm is pretty bright;) Wish more members would purchase a bunch of these 5V ones as they make great project modules and you CAN make them focusable if you just secure the bottom portion and use the top section to focus as it has the lens in it. At $5.41 each I can't think of a better bargain and three's a really good chance of getting over 100mW ones once set. Great way to learn to build with stuff around the house.
Oh yeah, always use BLF for a small discount on most things they sell. You can buy 5 of these for $25 with free shipping and they always seem to ship faster than the other Chinese places that ship for free.
 
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