I am trying to find a heat sink(TO-220) for a standalone mono LM1875 amp I am going to build and just can't find one with the specs that I am looking for.
I believe I need something with a dissipation of 19-20W and a thermal resistance of atleast 3°C/W or better. I tried digikey, mouser, allied but either I could found suitable dissipation or thermal resitance, but not both. They all carry the same Aavid Thermalloy heat sinks. Where else can I try (in usa) ?
I believe I need something with a dissipation of 19-20W and a thermal resistance of atleast 3°C/W or better. I tried digikey, mouser, allied but either I could found suitable dissipation or thermal resitance, but not both. They all carry the same Aavid Thermalloy heat sinks. Where else can I try (in usa) ?
EBay is a good place to look. Search on Heat Sink (two words). "Business and Industrial" and "Consumer Electronics" are good catagories to then look in.
I have used this guy:
http://search.ebay.com/_W0QQsassZbarrredboss
Very good. I ordered a couple 24" sections and had him cut (for free) into 4" pieces for a parts group buy. Very nice. Small enough for Chip or small trasistor applications, and a good size to double up for larger amps. I believe everyone was happy with the sinks, which have 2 LM3886s mounted on a 4" piece.
I have used this guy:
http://search.ebay.com/_W0QQsassZbarrredboss
Very good. I ordered a couple 24" sections and had him cut (for free) into 4" pieces for a parts group buy. Very nice. Small enough for Chip or small trasistor applications, and a good size to double up for larger amps. I believe everyone was happy with the sinks, which have 2 LM3886s mounted on a 4" piece.
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I've gotten excellent deals at American Science and Surplus. There is a retail outlet near me and I can usually pick up heat sinks sufficient for 387x and 478x chips for under $2.
They have a website- www.sciplus.com and may have some online. Of course since they are either surplus or overstocks or removed from equipment you never know what you might find (but that's half the fun).
They have a website- www.sciplus.com and may have some online. Of course since they are either surplus or overstocks or removed from equipment you never know what you might find (but that's half the fun).
Me, too. Ebay.
It looks like you were tinking of a PCB mounted heatsink. I'm not sure that works well except at very low powers like 20W or less. I tried that once and found a source for 3 inch high finned Avid-Thermolloy PBC mounted types fot TO-247. They were barely acceptable thermally and were so big that they could flex the PCB enough to crack solder joints. A "good" idea that wasn't.
Anyway if money is no object there are two other sources
www.mmmetals.com, and
www.conradheatsinks.com
The products are good but it may be expensive for what you are doing.
One more idea if you are a scrounger. This worked OK for me. Sometimes you can find used/surplus heatsinks for CPUs. Look for ones with the longest forest of posts you can find -- lots of surface area. Individually they are too small, but if you get several and bolt them very tightly (with thermal grease in between) to a piece of aluminum plate you can make a fair heatsink for almost nothing. When I do this the results are ugly but it works.
It looks like you were tinking of a PCB mounted heatsink. I'm not sure that works well except at very low powers like 20W or less. I tried that once and found a source for 3 inch high finned Avid-Thermolloy PBC mounted types fot TO-247. They were barely acceptable thermally and were so big that they could flex the PCB enough to crack solder joints. A "good" idea that wasn't.
Anyway if money is no object there are two other sources
www.mmmetals.com, and
www.conradheatsinks.com
The products are good but it may be expensive for what you are doing.
One more idea if you are a scrounger. This worked OK for me. Sometimes you can find used/surplus heatsinks for CPUs. Look for ones with the longest forest of posts you can find -- lots of surface area. Individually they are too small, but if you get several and bolt them very tightly (with thermal grease in between) to a piece of aluminum plate you can make a fair heatsink for almost nothing. When I do this the results are ugly but it works.
I usually borrow mine from scrap electronics. A good source is old PC heatsinks...There's always friends and people out there that are throwing away PCs or something else, so I always take it off their hands and use the heatsinks (among other things) from them. Making a TO-220 heatsink is pretty easy to make out of any heatsink too...I use a dremel to drill a hole through it and then put a screw and nut to hold the chip in place.
-Segasonicfan
-Segasonicfan
heat sinks in the UK
http://www.ppi-uk.com/heatsinks.html
but i did a price enquiry....
"We can supply our ‘T’ profile heatsink in three and half metre length at a price of £69.96 per metre (£244.86 per three and half metre length).
We can also cut to specific lengths.
Best Regards
Peter Addison
Power Products International Limited
Tel (0)1732 866424
Fax (0)1732 866399"
that's pretty steep...
http://www.ppi-uk.com/heatsinks.html
but i did a price enquiry....
"We can supply our ‘T’ profile heatsink in three and half metre length at a price of £69.96 per metre (£244.86 per three and half metre length).
We can also cut to specific lengths.
Best Regards
Peter Addison
Power Products International Limited
Tel (0)1732 866424
Fax (0)1732 866399"
that's pretty steep...
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