What to use for TO-220 isolating pad? - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 20th May 2003, 08:49 PM   #1
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Default What to use for TO-220 isolating pad?

What are you guys using to isolate your wide TO-220 packages like the LM3875?

Checking stores, all I can find are the thin flexible TO-3 pads (wrong shape) or the thick aluminum oxide for narrow TO-220 (too narrow).

Is there something more specific out there which I can't find?

How crazy would it be to drill 2 more holes in the 3875 and just use 3 TO-220 insulators?
__________________
Aerodynamics are for people who can't build engines. Enzo Ferrari
  Reply With Quote
Old 20th May 2003, 09:15 PM   #2
Netlist is offline Netlist  Belgium
diyAudio Moderator Emeritus
 
Netlist's Avatar
 
Join Date: Jan 2003
Quote:
How crazy would it be to drill 2 more holes in the 3875 and just use 3 TO-220 insulators?
The ultimate in DIY!!! It would be like drilling holes in ones brain to fasten its head before going under a scanner.

There are silpads available in larger formats (100x100mm) which you can cut into the desired format. Your local supplier must be able to provide them.
This for example: http://www.angliac.com/product_searc...cat_number=500

/Hugo
  Reply With Quote
Old 20th May 2003, 09:46 PM   #3
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
I'm using TO-220 aluminum oxide pads under LM1875. It works fine and sounds better than silpads (less damping, I guess, results in more airy sound).
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 20th May 2003, 09:57 PM   #4
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Quote:
I'm using TO-220 aluminum oxide pads under LM1875. It works fine and sounds better than silpads (less damping, I guess, results in more airy sound).
Peter, do you mean just the regular narrow TO-220 pads? So you are experiencing no issues with having some of the LM3875 mounting surface not in contact with the pad? If so, I would love to hear it!
__________________
Aerodynamics are for people who can't build engines. Enzo Ferrari
  Reply With Quote
Old 20th May 2003, 10:04 PM   #5
UrSv is offline UrSv  Sweden
diyAudio Member
 
UrSv's Avatar
 
Join Date: Jan 2002
Location: Sweden
Quote:
Originally posted by leadbelly


Peter, do you mean just the regular narrow TO-220 pads? So you are experiencing no issues with having some of the LM3875 mounting surface not in contact with the pad? If so, I would love to hear it!
Peter was talking LM1875 which is in TO-220. LM3875 is in 11 pin MultiWatt which is small enough to fit on a TO-3P (not TO-3) pad. To use TO-220 pads under a LM3875 seems pointless since TO-3P are readily available. The MultiWatt size is hard to come by and the only place I've seen it is Schuro.
__________________
UrSv
Those who say it can't be done should not stop those who are doing it.
  Reply With Quote
Old 20th May 2003, 10:17 PM   #6
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
I got everything mixed up. I meant LM3875 and TO-247 pads pictured below. They measure 14 x 19.5mm and I think are sold indeed as TO-220, but fit TO 247 and are the same as TO-3 P (I guess). The sides of a chip are sticking out a bit, but I didn't have any problems because of that so far. I really like to use those aluminum oxide pads here, as I said before, they sound better and provide extra clearance between heatsink and pins for a feedback resistor.
Attached Images
File Type: jpg al.jpg (49.2 KB, 736 views)
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 20th May 2003, 10:21 PM   #7
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Woo-hoo...thanks Peter, I already bought some of those
__________________
Aerodynamics are for people who can't build engines. Enzo Ferrari
  Reply With Quote
Old 22nd May 2003, 09:41 PM   #8
rljones is offline rljones  United States
diyAudio Member
 
Join Date: Mar 2001
Location: california
I've used the Multi size, like digikey part BER118-ND for the LM3875 or the TDA7294. A less expensive option is BER190-ND in the same size.

regards, robert
  Reply With Quote
Old 23rd May 2003, 08:41 PM   #9
cm961 is offline cm961  Canada
diyAudio Member
 
cm961's Avatar
 
Join Date: Jun 2001
Location: Peterborough, Ontario
These chips are availible in isolated packages, you could try that.
LM3875TF intead of LM3875T.

Hope that helps.
Pete
  Reply With Quote
Old 11th July 2003, 03:03 PM   #10
diyAudio Member
 
Matttcattt's Avatar
 
Join Date: Feb 2003
Location: Bristol
i used top3, and made a new hole, they are the perfect size. they are 22mm by 18mm, i just turned it sideways and made a hole at the top. see image.
Attached Images
File Type: gif deleteplease.gif (1.9 KB, 431 views)
__________________
If it aint broke, don't fix it. If it is broke, fix it.
If you can't fix it, take it apart and see how it "worked".
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Isolating a hum? Bogie Solid State 10 26th January 2005 02:14 PM
Isolating each Mos-Fet? richeros Solid State 14 13th April 2003 11:19 PM


New To Site? Need Help?

All times are GMT. The time now is 06:08 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2