LFS: Cheap big heatsinks - Page 1
Forum section: electronics / general

author: apis
author_rank: Super Contributor
timestamp: March 23, 2016, 09:50:53 pm
content: I've been trying to find a cheap source for heat-sinks, small ones is not a problem but big ones (like the one in the BK precision) cost an arm and a leg even on ebay. Does anyone know where to get something cheap or some diy alternative? Feels kind of silly when a small piece of extruded aluminium is the most expensive part of a project.

author: timb
author_rank: Super Contributor
timestamp: March 24, 2016, 01:41:33 am
content: Check outwww.allelectronics.comin the Heatsink section. They've got a couple of massive ones in stock at decent prices.

author: Farley
author_rank: Regular Contributor
timestamp: March 24, 2016, 01:48:12 am
content: I've had good experiences with HeatsinkUSA. They state that they ship internationally.http://www.heatsinkusa.com/

author: owiecc
author_rank: Frequent Contributor
timestamp: March 24, 2016, 09:12:39 am
content: DIY alternative: you can find plenty of old PC CPU heatsinks for peanuts. Rated for 100-150W processors they will give you Rth<0.5 K/W. I have a stack of them from my university electronics trash dump. Try your local kretsloppspark

author: TopLoser
author_rank: Unknown
timestamp: March 24, 2016, 10:40:54 am
content: I have a huge quantity of nice new heatsinks. All sorts of shapes and sizes, including some really big high quality heatsinks. Show me what sort of size and shape you're after and I'll see what I have that matches up.

author: PaulAm
author_rank: Frequent Contributor
timestamp: March 24, 2016, 09:13:19 pm
content: It's not quite as effective, but you can just use a big chunk of aluminum. I had a UPS where they just bolted all of the MOSFETs to a one inch square bar of Aluminum about 10 inches long.

author: apis
author_rank: Super Contributor
timestamp: March 27, 2016, 09:48:10 pm
content: Thanks for the ideas and links! Sorry for not answering until now but it has been a busy Easter and I had to spend most of it in the hospital when not feeding cats (long story but everything worked out ok in the end).All Electronics only ship to North America it seems but HeatsinkUSA looks very promising.Using CPU heatsinks is a great idea, might have a couple of old ones in the attic actually, since they change motherboard and cpu specs all the time the old ones can't be used as parts in new computers anyway. The way they are usually shaped means they don't fit nicely into a standard sized enclosure though.I've been thinking of using simply "u-bar" aluminium pieces, but square bar might be better, I wonder if there is an easy formula for estimating the thermal resistance? A computer program perhaps?TopLoser:Thanks for the offer. I was thinking of a more permanent solution though, I figure this must be a problem that more people than I are having!

author: Jeroen3
author_rank: Super Contributor
timestamp: March 27, 2016, 09:59:36 pm
content: The fan heatsink aggregates are indeed expensive.http://www.fischerelektronik.de/has some. Cheapest I could find was this one for 50 euro.http://nl.farnell.com/2497193But expect it to be more than 1 K/W.You're better off searching eBay for used (or new) heatsinks of pc's and servers.Mounting can be a challenge though.

author: jeffsf
author_rank: Contributor
timestamp: March 31, 2016, 10:03:43 pm
content: One thing you might look for would be surplus cellular/communication amplifiers. At least in the US, there has been a steady flow of decommissioned amps as the bands and modulation types have changed.I've lost more hair (and skin off my knuckles) getting "cheap, surplus" heatsinks to work both in terms of attachment to the devices, as well as to the case. I have no idea if shipping cost would be prohibitive for you, but I am aware ofhttp://www.heatsinkusa.com/who have multiple profiles available and you buy the length you need.Caveat:I haven't purchased through them myself. I have seen them used in a few kilowatt-class amplifier projects.

author: lwatts666
author_rank: Unknown
timestamp: April 01, 2016, 05:03:32 am
content: The late, great Bob Pease was reported to have picked up an old VW cylinder head dumped on the side of the road, dragged it back to the lab and used it as a heat sink for some project he was designing.

author: DaveSanderson
author_rank: Newbie
timestamp: April 01, 2016, 07:29:17 pm
content: I have to throw in a +1 for Heatsinkusa.com, they are supper helpful, have a good range of options and you can get them in arbitrary sizes.

author: SeanB
author_rank: Super Contributor
timestamp: April 02, 2016, 07:24:22 am
content: Got a pair of 400W rated heatsinks going off to the scrapyard. Rated for 400W continous power, as they came off a dead HMA9500 amplifier, which was also better known as a 1 bar room heater, seeing as it was a class A amplifier and used a constant 950W of power, even when with low signal levels. Scrapped because it has a fault somewhere, and I really do not need a 30kg toaster, plus i stubbed my toes on the thing one time too many.Of the 30kg 7kg is heatsink, and 14kg is power transformers potted in resin. Then 15000uF of capacitor per power rail, and separate positive and negative rails per channel. Just WTF did Hitachi use a 3A diode as main rectifier? Is the regulation on the transformer that poor that they could get away with it.

author: apis
author_rank: Super Contributor
timestamp: April 02, 2016, 09:49:38 pm
content: Datasheet/app notes from major manufacturers sounds like a good source of information, thanks.The problem with scavenging old gear, if you have access to old gear with massive heatsinks you are probably in a place where you could have managed without. Dave's dumpster is a good example of this phenomena.For whosoever hath, to him shall be given.Found this AliExpress seller while looking around, haven't ordered anything from them though so beware:http://www.aliexpress.com/store/837012Thanks for replies!