heatsinks

Greetings One and all

I'am a complete newbie to DIY electronic, thus the Grasshopper. I'am taking a stab at building a 25 watt SON and wondering if any one has a cheap source for heatsinks in the eastern Canada area or further afield if need be. I know it will require massive amounts of HS.
Homebrewed designs are most welcome.
 
It's not an amplifier...it's a space heater that makes music. That's part of why I've got the SOZ w/current sources thread going. Dreadfully inefficient.
Good thing that winter's coming on--at least here in the Northern hemisphere. (Just ask me if I love having a pair of Alephs and a pair of tube amps to help warm up my listening room.)

Grey
 
you have 12 devices per 17" length right?

that means you have roughly 2 devices for each 3 inch length....

that's 48W...the Rjc is 0.83, Rcs is 0.2 and the Rsa for each 3 inch length is 0.8. So 48W * (0.83 + 0.2 + 0.8) = about 88 degrees difference between ambient and junction temperature....thats perfectly ok! It's actually a bit better than this as the 48W per 3" length aren't centered at one particular point and are spread pretty much evenly over the 3 inches....
 

rtirion

Member
2000-11-24 12:02 am
jduncan

How do you get Rcs (R case to sink) at 0.2C/W?
When you need to electrically isolate the FET from the sink reaching 0.2C/W is quite a challenge. Readely available materials such as mica with silicon grease or silicon pads will not come close. BeO, Kapton are very hard to come by.

In practice I can get 0.5 to 0.6C/W with mica and silicon grease. In your example this would mean very hot sinks and probaly a short lifespan for the amplifier, or am I missing something?