Transformer insulateing tape?
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From: Archimedes' Lever on 19 Jun 2010 23:37 On Sat, 19 Jun 2010 21:47:50 -0400, Hammy <spam(a)spam.com> wrote: > Yes I'm hand twisting the wires and thanks for the tip about being to >tight I had forgotten about the optimum twist per inch. >> Yeah, in a transformer especially, a tightly twisted set of wires actually introduces detrimental effects. In a cable bundle it usually amounts to a mere binding of the cables, usually causing more tension on one than another. Not much problem with a short run inside a chassis, but a major factor on say a 150' long cable for a jolly green giant or the like. All the stresses have to be normalized.
From: Archimedes' Lever on 19 Jun 2010 23:47 On Sat, 19 Jun 2010 20:08:16 -0700 (PDT), Bill Sloman <bill.sloman(a)ieee.org> wrote: >The polyester backing film is nominally 1 mil thick, but with the >adhesive it builds up to 2.5 mils - nominally 63.5 microns. We used it >between layers of round wire, so presumably some of the adhesive was >squeezed sideways into the gaps between the wires. Nope. Plenty of variations about. I had a lot of .5 mil tape with .5 mil adhesive. The taut use of the tape will cold flow it as far into any crevices it can. Then baking 'relaxes' it 'in' further.
From: Cydrome Leader on 20 Jun 2010 02:07 Hammy <spam(a)spam.com> wrote: > On Sat, 19 Jun 2010 22:47:52 +0000 (UTC), Cydrome Leader > <presence(a)MUNGEpanix.com> wrote: > >>Hammy <spam(a)spam.com> wrote: >>> >>> What kind of tape can you use for insulation between primary to >>> secondary of flyback transformer. I know mass produced professional >>> designs use a 3M specialty tape. What I'm looking for is a tape I >>> could pick up at Staples or some office supply store or hardware >>> store. >>> >>> The vinyl electrical tape I can find is only rated for 600V and 80C >>> MAX TEMP. >>> >>> Is there a commonly available tape that is good for higher temp and >>> offers higher insulation? I've read of people using a mylar tape is >>> there a brand name ,type anyone could recommend? >>> >>> This is for a 90 - 140Vac input flyback. >> >>are you making one transformer or many, and if so, are you using a coil >>form? > > Just one. I'm using an ETD29 core with Bobbin. I've made several > transformers for LVDC less then 50Vrms.This is my first transformer > from scratch for a line powered supply. I usually just buy or get > samples from places like coil craft, but I want a multiple output > flyback 50W small light weight and I've got this down too fitting into > a 5" x 3" x2.2" in enclosure. I know I could buy one for $50 to 100 > plus but that's no fun;-) > > I will be the only one using it. Its main purpose is to save bench > space and to save me the hassle of having to continually dig out 317's > 7812 or 7805's when I'm working on something that requires multiple > voltages. > > So its not going to be tested for EMC compliance (but I do have a line > filter) or Hi Pot tested etc. > > I originally did it up to operate of my Bench top PSU with an EFD20 > core/ bobbin set (for 24W ) but I want to be able to eliminate the > larger Bench top PSU so I don't have so much clutter on the bench. > > Eventually I'll get around to building a half decent sized bench, but > I just finished installing and painting seven new interior doors. > That's my renovating fun for a couple of months anyway's. ;-) This info helps quite a bit. For a single unit you might be able to scavenge the yellow tape from a junked switching power supply from from a computer. Some peel apart if you smash the ferrite, some don't. Do avoid plain electrical tape- it creeps and "pressure" inside a coil with hundreds or thousands of turns can sink right though it. Other sources of insulating material are in your junk pile. Those white plastic sheets that replace fish paper to keep pins from hitting close fitting chassies can be cut up and used. Junked computer power supplies have lots of goodies like this inside them. It works fine for quick and dirty projects. secure it with scraps whatever tape you can peel from a transformer or inductor and you're good.
From: Cydrome Leader on 20 Jun 2010 02:16 Archimedes' Lever <OneBigLever(a)infiniteseries.org> wrote: > On Sat, 19 Jun 2010 20:01:03 -0400, Jamie > <jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote: > >>Years ago for non critical apps, we used wax paper for layer >>insulation for winding multilayers.. > > It was referred to as 'fish paper'. You would wind bobbin-less transformers on old newspapers if you wanted to. The trick is to wind many coils at once next to each other, stop the winder and insert a sheet of [anything] and wind the next layer and repeat. When done with all of that, you saw or cut the individual windings apart. Trying to make one coil that way would be almost impossible as the windings would slide off the edges and the insulating material would collapse at the edges as well.
From: Archimedes' Lever on 20 Jun 2010 02:41
On Sun, 20 Jun 2010 06:07:33 +0000 (UTC), Cydrome Leader <presence(a)MUNGEpanix.com> wrote: >For a single unit you might be able to scavenge the yellow tape from a >junked switching power supply from from a computer. Some peel apart if you >smash the ferrite, some don't. Even if it would, the adhesive is pressure sensitive, and will have polymerized, and be unusable for subsequent use, unless you wanted to do it without the adhesive. |