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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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29th Aug 2019, 9:54 pm | #1 |
Nonode
Join Date: May 2016
Location: Cornwall, UK.
Posts: 2,333
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Grey insulating cardboard
Ahoy,
In my Uhers there are rather fine pieces of thin, stiff, grey cardboard used between circuit boards and covers. Perhaps they aren't anything special, but they have nice pressed, smooth, shiny surfaces. If I wanted to use anything similiar in my own projects, or replace something in an old piece of equipment, does anyone know the name of this cardboard equivalent, or if it's something one can still buy today? Does it have ratings or did they just use bits of cereal packet? |
29th Aug 2019, 10:12 pm | #2 |
Nonode
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
Posts: 2,350
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Re: Grey insulating cardboard
I dismantled so old battery drill batteries for cell renewal. They had similar card under and around the cells. I replaced it with card cut from a "hanger" out of a filing cabinet. The sort which slide in and out with the files sitting in the "cradle".
try that. Les. |
29th Aug 2019, 10:30 pm | #3 |
Nonode
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,587
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Re: Grey insulating cardboard
Is this a corrugated plastic material? If so, the brand name is Correx and sheets are widely available in different sizes. Probably something different.
Alan |
29th Aug 2019, 11:07 pm | #4 |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: Grey insulating cardboard
This is the card I always use for those applications & more:
https://www.jaycar.com.au/pressboard...erial/p/HG9985 It is around 1mm thick and for cardboard it has an amazing dielectric strength. It also looks very good varnished.Have a look at the battery case made out of it on page 12-13 of this article: http://worldphaco.com/uploads/USING_...CILLOSCOPE.pdf PS: the original card Jaycar supplied was a redish color, like that in the article, of late it has changed to a pale brownish color but it is electrically identical. Last edited by Argus25; 29th Aug 2019 at 11:15 pm. |
29th Aug 2019, 11:49 pm | #5 |
Hexode
Join Date: Aug 2014
Location: Featherstone, West Yorkshire, UK.
Posts: 386
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Re: Grey insulating cardboard
The thin grey cardboard is called FISH PAPER.
It is used on a lot of stereo high power amplifiers, where the two amplifier channel boards have to be insulated from the metal cabinet. If you have a local Pro Audio power amp repair company, they may well have some. I had 20 sheets in stock in my department, before I was made redundant. I doubt it is still there, the new management who took over sent many thousands of pounds worth of parts to the tip. Kevin |
30th Aug 2019, 1:03 am | #6 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,535
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Re: Grey insulating cardboard
Sounds like what I knew as "Elephantide"- a stiff grey-blue card like sheet material.
Try this: RS Stock No. 775-7790
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30th Aug 2019, 1:16 am | #7 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,339
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Re: Grey insulating cardboard
Yes, "Elephantide"
The use of ordinary cardboard is fraught with danger. In damp/humid climes, it can absorb moisture and not only become conductive but it also promotes corrosion when in contact with metallic surfaces. If you really, absolutely, must use cardboard, soak it in varnish or shellac and let it dry thoroughly before use. |
30th Aug 2019, 7:41 am | #8 |
Nonode
Join Date: May 2016
Location: Cornwall, UK.
Posts: 2,333
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Re: Grey insulating cardboard
Once again, the hive mind comes up trumps! Looking at listings for 'fish paper' and the RS link, I think we've found it.
As so often with the Infobahn the crucial thing is discovering the right search terms. I'll get some of this and compare it what I have. It's certainly more like cardboard than plasticard. Thanks all - don't worry Terry_VK5TM, I don't think I'll be desperate to put any projects in cardboard boxes! Shellac, however, is a lovely material with many uses... |
30th Aug 2019, 8:03 am | #9 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,864
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Re: Grey insulating cardboard
Transformer winding firms are likely to stock fish paper in some of the thinner grades.
I've always wondered just what fish have to do with it. David
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30th Aug 2019, 9:48 am | #10 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,339
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Re: Grey insulating cardboard
And just so you can be spoilt for choice:
RS 775-7794 PET, Press Paper Elephantide Laminated Presspaper |
30th Aug 2019, 10:28 am | #11 |
Nonode
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,587
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Re: Grey insulating cardboard
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1st Sep 2019, 7:33 am | #12 |
Heptode
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 664
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Re: Grey insulating cardboard
Fish paper comes in various colors and thicknesses.
When I need any, I go to my local electrical wholesale shop and they sell me some. Other sources might be motor rewinders & transformer mfgr's. |
1st Sep 2019, 8:14 am | #13 | |
Heptode
Join Date: Jan 2008
Location: Durham, County Durham, UK.
Posts: 826
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Re: Grey insulating cardboard
Quote:
https://secure.presspahn.com/Cart/in...2g8li0aihgugg0 John |
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1st Sep 2019, 11:40 am | #14 |
Octode
Join Date: Sep 2017
Location: Bristol, UK.
Posts: 1,654
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Re: Grey insulating cardboard
When I was looking for some on the web, it seemed much more readily available in the US than in Europe or UK. Can't think why...
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2nd Sep 2019, 12:45 pm | #15 |
Nonode
Join Date: May 2016
Location: Cornwall, UK.
Posts: 2,333
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Re: Grey insulating cardboard
Thanks for the tip, stitch1. Unfortunately Presspahn only sell brown (I happen to like the blue!) so it wouldn't match the Uhers, but the site looks an excellent source for all those materials I'm never quite sure where to get.
ajgriff - I hope they just used newspaper as this stuff seems rather too heavy-duty for real fish! Unless they needed the insulation for the stingray tails... FrankB - this is where the US has some advantages over the UK. Here it's very rare to find such a shop, and they'll only sell lowest common denominator parts anyway. A real nadir was when I couldn't find anywhere in Brighton to buy good quality mains flex, an in-line switch and a good plug. I was reduced to Homebase with plastic packets of cheap and nasty pieces sold at outrageous prices. |
2nd Sep 2019, 2:01 pm | #16 |
Nonode
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,587
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Re: Grey insulating cardboard
I'd guess that old fish wives would have sourced extra thin paper from the US.
Alan |
8th Nov 2019, 11:01 pm | #17 |
Nonode
Join Date: May 2016
Location: Cornwall, UK.
Posts: 2,333
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Re: Grey insulating cardboard
I got some of the RS Elephantide. It looks the part except one side has a very shiny plastic film on. I'm not sure if I'm supposed to leave this on or take it off - it doesn't peel off easily, and leaves a torn surface behind so it's not an adhesive protector.
The datasheet says '100% cotton' so is this some part of the process? The stuff already in the Uher is matt both sides, so I don't know if one side or the other is supposed to be 'hot'. As it's just a shield so the broken main board doesn't touch the bottom cover it won't matter, but it might if I'm supposed to use it the right way round in a valve situation! |
9th Nov 2019, 12:48 am | #18 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,339
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Re: Grey insulating cardboard
Even the manufacturers don't specify which side is "up", so I guess it doesn't matter.
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9th Nov 2019, 12:58 am | #19 |
Banned
Join Date: Jun 2015
Location: Mareeba, North Queensland, Australia
Posts: 2,704
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Re: Grey insulating cardboard
Dad ( master rewinder and design engineer) always said shiny side to hi volts. I didnt ask, and he never said why.
Joe |
9th Nov 2019, 5:39 pm | #20 |
Nonode
Join Date: May 2016
Location: Cornwall, UK.
Posts: 2,333
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Re: Grey insulating cardboard
Thanks both. It looks like for this application, aesthetics wins out and it's shiny side down to match the rest.
Why I mind I don't know - who else is going to look inside the bottom of an old cassette desk and notice it? Perhaps it's like Gaudi and the Sagrada Familia in Barcelona - on being asked by a bishop why he'd designed golden angels right up on the top of the spires where no-one could see them, he replied 'God will see them'. |