heatsink mounting Q

[woodturner-fran]

Hi all,

I've just embarked on putting together a mini-aleph for my full range speakers. I've really only done work with tubes before so be gentle with me 😀

Believe it or not, but its actually quite hard to locate the info readily on all of this stuff!! So I've 2 questions:

1. heatsink: will a heatsink measuring 3" by 8" with 1 1/4" vanes with a 1/4" solid plate bottom be enough for one board? My second choice is one thats 4" x 8" with only 1" vanes.

2. Will a TO-220 mounting kit (insulating pad and bush) fit the TO247 package that the mosfets are?


TIA and sorry for what must be obvious questions....

Fran

 

[richie00boy]

The TO-220 pad is too small for the TO-247. You probably won't need a mounting bush as the TO-247 hole is surrounded by plastic usually.

 

[bays_9a5tt]

2. Will a TO-220 mounting kit (insulating pad and bush) fit the TO247 package that the mosfets are?

if you cannot locate pads for TO247, take TO3 pad and trim the excess material.

 

[jackinnj]

The BER118 thermal pads will work for TO-247 or TO3-P -- they are available from DK

You need to specify the number of fins if you want to guestimate the thermal impedance of the heatsink -- assuming 10 theta = 2.1

 

[woodturner-fran]

OK,

thanks for that. The insulating pad then would be this one:

farnell link

jackiinj: I'll download one of the online calculators and see. AFAIK, the mini-A will dissipate about 45W per side so I'm aiming for a heatsink of about 1deg/W. Something like this one, but the one I have to hand has deeper fins:

second link


What do you guys think?

Fran

 

[nicoch58]

HI

for FR aren't more appropriate the F2 current source ?

 

[woodturner-fran]

I hear people recommending the F4 as well so I don't know for sure.


Fran