Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Need to insulate E-I laminations
Need to insulate E-I laminations
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 5th September 2019, 09:57 PM   #1
mskl99 is offline mskl99  United States
diyAudio Member
 
Join Date: Jul 2011
Location: Connecticut
Need to insulate E-I laminations
Default Need to insulate E-I laminations

Finally decided to build a transformer. I found an old transformer to disassemble for the E-I laminations and the bobbin, but it was so heavily varnished that there was no way to get the laminations out without boiling. Once I removed the laminations this way, they seem to be stripped of everything. There is absolutely no insulation.

Can I just put some transformer varnish on each of the laminations before stacking and expect reasonable insulation?
Thanks,
Mike
  Reply With Quote
Old 5th September 2019, 10:11 PM   #2
maton00 is offline maton00  Mexico
diyAudio Member
 
maton00's Avatar
 
Join Date: Feb 2012
Location: Queretaro
Send a message via MSN to maton00
You can try, in the worse escenario your transformer will only have "more" loses, but you can compensate with the windings and a aproximate saturation calculation, professionaly made transformers do soak the entire transformer in a varnish cube and do extract the air with a vaccum pump to ideally impregnate every space of air, but is also quality, dependant, at the end the transformers may have imperfections in your case lots of metal laminations may touch and that will certainly only reduce its performance, but it wont cause it to be totally unusable, there is people that uses Western Electric century old cores to do output transformers for vaccum tube amplifiers (an application of a transformer where the electric parameters are totaly dependant with the final product quality), and they have lots of acceptance, in the audio niche market, where is supposed to be expected the last quality and perfection ever.
  Reply With Quote
Old 7th September 2019, 12:55 PM   #3
mskl99 is offline mskl99  United States
diyAudio Member
 
Join Date: Jul 2011
Location: Connecticut
Need to insulate E-I laminations
Anybody? I've seen several threads on this forum discussing various varnishes, vacuum impregnation, etc, but I can't find any information about insulating laminations from each other.
  Reply With Quote
Old 7th September 2019, 05:03 PM   #4
lcsaszar is offline lcsaszar  Hungary
diyAudio Member
 
Join Date: Mar 2004
Location: Budapest, Hungary
I have done it by painting them with phosphoric acid rust passivator. It is a blueish water-like liquid, and creates a thin white coating on the sheets. The goal is to insulate them electrically, and it does the job. You can get it in car accessories shops.
  Reply With Quote
Old 7th September 2019, 05:07 PM   #5
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
Nowadays, laminations are almost always insulated by oxidation or a similar surface treatment, or sometimes by a mineral coating like Carlite.

This means that it cannot be removed or dissolved, it can just be mechanically or chemically stripped

Very old techniques were based on paper or varnish, but that's normally not the case anymore, except in special fabrications
__________________
. .Circlophone your life !!!! . . ♫♪ My little cheap Circlophone© ♫♪
Electrify your daily life!!! ....⚡⚡ ELEKTRIA ⚡⚡
  Reply With Quote
Old 7th September 2019, 05:09 PM   #6
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
Factory lams are often treated with steam. A thin almost-invisible layer of oxide (rust) is all it takes. It does not have to be "100% glass", it only has to be much lower conductance than Silicon Iron over most of the contact.

Since steam-treat needs precise control, I'd think shellac or varnish is the way to go DIY.
  Reply With Quote
Old 8th September 2019, 07:59 AM   #7
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
Quote:
Originally Posted by mskl99 View Post
they seem to be stripped of everything.
What I meant is that boiling water alone is unlikely to have removed the (invisible) insulation, unless you added some chemical
__________________
. .Circlophone your life !!!! . . ♫♪ My little cheap Circlophone© ♫♪
Electrify your daily life!!! ....⚡⚡ ELEKTRIA ⚡⚡
  Reply With Quote
Old 8th September 2019, 09:18 AM   #8
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Agree with Elvee: boiling, solvents, even boiling in lye won´t remove sh*t (pardon the French).

While any acid treatment, including Phosphoric *may* so in principle avoid it.

Unless you sanded or blasted your laminations, you´ll be fine.

And surface treatment is not *that* invisible either; greenish / bluish / greyish surface *is* the actual insulation treatment.

Microns thick? ... thick enough,.

"If it weren´t there" surface would be "plain iron coloured" , like, say, what you find on a nail, or when you sand/grind iron sheet "down to the bare metal" and prof of that is that it quickly starts rusting, red rust that is.

While surface treatments *are* some kind of rust but far stronger and stable ones.

And rust spots here and there don´pt hurt.
__________________
Design/make/service musical stuff in Buenos Aires, Argentina, since 1969.
  Reply With Quote
Old 9th September 2019, 05:53 PM   #9
Mark Tillotson is offline Mark Tillotson
diyAudio Member
 
Join Date: May 2018
Location: Cambridge UK
Very thin layer of varnish is all it takes - the voltages are tiny, the requirement is to reduce losses between laminations to less than the losses within laminations (thereafter you only get better performance by going to thinner laminations).
  Reply With Quote
Old 9th September 2019, 06:11 PM   #10
GoatGuy is offline GoatGuy  United States
diyAudio Member
 
GoatGuy's Avatar
 
Join Date: Dec 2012
Location: SF Bay Area
Simple solution… put a stack of E (or I, but E is easier) between two sheets of plywood, in a vise. With a sheet of copper (just a bit will do) on each side, soldered to wires.

Then while it is compressed in a vise, hard enough to slightly indent the wood, measure the resistance.

If it is above 100 kΩ, you're golden. If below, then consider VERY light application of varnish to the lams.

If your varnish is acetone soluble (most are), then diluting 1 unit of varnish in 20 units of acetone is good. Dip the lams, don't spray. They'll dry off in less than a minute. It goes pretty quickly!

Old, old timer … the Goat … having done this.

Just saying,
GoatGuy ✓
__________________
Burnished unicorn horn circuit design only go so far. When the unicorn's magic fails, its best to rely on maths. JustSaying™
  Reply With Quote

Reply


Need to insulate E-I laminationsHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
PT laminations are usable as OT laminations ? Kagliostro Tubes / Valves 26 7th September 2012 11:29 PM
Cheap ways to insulate a wire stator vmk Planars & Exotics 1 30th April 2010 07:52 AM
Another way to insulate transistors from heatsinks frags Pass Labs 19 31st August 2009 01:34 PM
why insulate transistors???? dognut Parts 14 4th May 2009 02:37 AM
Is it OK to insulate a heat sink? mtl777 Parts 15 6th April 2008 10:39 AM


New To Site? Need Help?

All times are GMT. The time now is 06:06 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki