Go Back   Home > Forums > Design & Build > Construction Tips

Construction Tips Construction techniques and tips

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 2nd March 2012, 09:36 AM   #1
diyAudio Member
 
Join Date: May 2004
Location: Sydney
Default Aluminium flat or not in PSU?

I have been using aluminium flat to connect screw mount reservoir capacitors in my power amplifier power supply. I prefer aluminium flat as it is clean and tindy with far less soldering to do. Conductivity is excellent given the thickness and width of the aluminium flat.

However, I have just looked up aluminium in Wikipedia, and found that aluminium when exposed in air forms a thin layer of aluminium oxide in a fraction of a second.

I am wondering if contact resistance is high with aluminium due to oxidation and whether it is a good idea or not to use aluminium flat or not.
  Reply With Quote
Old 2nd March 2012, 11:23 AM   #2
diyAudio Member
 
Juergen Knoop's Avatar
 
Join Date: Jan 2007
Blog Entries: 3
usually this is fine, you might want to use toothed washers to be on the safe side...
  Reply With Quote
Old 2nd March 2012, 12:04 PM   #3
diyAudio Member
 
Join Date: Jan 2012
Clean the mating surfaces with a fine abrasive and connect together asap . I have seen plank like bus bar joints filed through a layer of vasaline to inhibit the oxidation , the surfaces then cleaned with more vasaline and the joint made and checked with a moving mirror galvanometer , but thats a bit extreme as they were going to carry hundreds of Amperes.
  Reply With Quote
Old 2nd March 2012, 09:59 PM   #4
diyAudio Member
 
Join Date: May 2004
Location: Sydney
Thanks for your input.

My worry is that from the Wikipedia site it says that the oxidation occurs within a fraction of a second (in pS) and it is all done.

In theory, the oxide reduces conductivity. In reality, the multimeter does not show resistance. But then I can't trust the multimeter because it does not have the resolution.

I guess the safest way to do it is that the connection to the PCB is directly connected to the last cap's screw terminal, rather than on the aluminium flat. The small resistance between the caps probably does not matter.
  Reply With Quote
Old 2nd March 2012, 10:03 PM   #5
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Most computer grade capacitors have aluminum screw terminals! Yes the oxide forms fast but that is thin and a good toothed lockwasher has been worked for 40+ years in many pieces of gear!
  Reply With Quote
Old 3rd March 2012, 12:38 AM   #6
diyAudio Member
 
Join Date: May 2004
Location: Sydney
Great. I will keep the aluminium flat and will look for toothed lockwashers.
  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
Flat FR, Flat Power Response, in-phase crossover? RockLeeEV Multi-Way 15 7th February 2012 08:07 PM
flat sub for flat TV Artmaster Subwoofers 0 17th December 2008 11:15 AM
How Flat is "Flat"? (XT18WO + 27TBFC-G = MTM) zenon Multi-Way 3 21st January 2007 03:15 PM
Inox or Aluminium ElectroPower Chip Amps 2 5th December 2004 12:32 AM
Aluminium soldering bm_mode Everything Else 13 29th October 2002 04:51 PM


New To Site? Need Help?

All times are GMT. The time now is 08:38 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