The Heatsink from Hell
Hacker's Bench Blog Archive

June 20, 2006
The Heatsink from Hell
So, the title on the eBay auction was "Large Rectifier", and sure enough the photo showed what appeared to be two fairly large heat sinks with a couple of stud-diodes bolted inbetween. The opening bid was $0.99 and the seller was nearby (no shipping) so I bid a dollar. What the heck.

Well I won it. When I went to pick it and a dozen other lots up the girl rolled all of my other stuff out on a cart, and then asked me if I'd mind going back into their warehouse and getting the rectifier myself. I went and found it. While I could lift it, I couldn't carry it any distance! I dug up a hand cart and got the box into my van and got it home.

Back at the ranch I wrestled the thing out of its box and it looked exactly like the picture in the eBay auction except that it was easily 4 TIMES bigger than I had thought! It is 14" by 10" by 10", and according to my bathroom scale weighs in at 72 pounds. (It actually dented the scale ... Lisa's gonna kill me)

The device is actually three heatsinks with 2 gigantic diodes between them making a half-wave bridge. There are no part numbers or clues on the assembly that I could find on the web, but I did look up the part numbers on the diodes (SW14CXC14C). Now, I've used a lot of diodes in my time, and have designed and built plenty of power supplies, but ...

1400 VOLTS AT 3270 AMPS ?!?!?! YIKES!

That's ... um ... P=IxE .... where's my calculator? ..... 4578000 Watts? ... 4.6 MEGAWATTS??!!

Somebody tell me I'm doing my math wrong!

Cool as that may be, I don't see "build a power supply for a nuclear submarine" anywhere on my honey-do list, so what the heck am I going to do with it? 70 pounds puts it well out of the doorstop/book end catagory and I don't have a boat (gratuitous joke for ham radio guys). Since a soda can weighs about a half of an ounce, or 32 cans to the pound, selling it to my scrap metals guy would bring 2,240 brand spanking new Diet Coke cans into the world, and give me about $31 (not bad for a $1 investment). So selling it for scrap is the obvious choice.

But I'd hate to do that. I usually find that "obvious choices" are painfully pedestrian. Besides, the thing is cool, and it would be cooler still if I could find someone that could use it as is. I just don't know who that is (DOD? NRC?). So, if you have any bright ideas on how to save this treasure from the recyclers crucible drop me a line at :
hbws (at)

July 15, 2006
Object de' Heatsink Art
The saga of the Heatsink From Hell (H.F.H.) continues. I called and had a grand chat with the teacher who oversees the electric car racing team at a local high school. It seems that the motor controllers they use already have all of the heat sinking they need so they really couldn't put it to good use. I also received a lot of emails from folks who begged me not to sell it off for scrap. Most all of them said that they'd love to have it, but no one was willing to pony up a reasonable offer and pay for shipping.

I also got a lot of suggested applications in my email, and I'm trying to decide if I should be scared that so many people out there are designing and building high powered rail guns!!!

Then there are the laser power supply folks, the 12-pack beer can cooler guy, the Stirling engine crowd, and one email that went on for three pages about 'thermal capacitors' ( which included enough formulas to give me nightmares about high school calculus class). I even got a few emails from ham radio guys who didn't want the heatsink, but just wanted to tell me they 'got' the boat anchor joke. :-)

So, no ideas that I can really use, and no one willing to pay a fair price for the H.F.H. so there it sits.

I did have a thought, though. I work in a small detached office in my backyard, and I have a new window-style air conditioner to fight the 110 degree days here in Arizona. It hums and blows valiantly, but it has a really hard time getting the space cooled down when it's really hot outside. If I somehow attached the condensing coil of the A/C unit to the heat sink, and added a decent fan, perhaps it would struggle a little less.

I need to find an A/C expert. But in the mean time; it's 112 degrees outside, the H.F.H. is too hot to touch without welding gloves, and I'm disinclined to do any real work out there anyway. So there it sits: The 'coolest' lawn ornament in the neighborhood.
July 19, 2006
Aire on a Heatsink
Damn. While my idea about running the condenser coil of my air conditioner through the H.F.H. would work (according to the guy that installed the 5-ton unit on my house), the cost of tearing apart the A/C unit, adding in the plumbing, and then recharging it would cost a little bit more than replacing my window unit with a much larger (and more efficient) one.

A friend of my neighbor wants to bolt it to the trunk lid of her 1971 Buick art car. 8-/

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