Transformer insulateing tape?
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From: Jan Panteltje on 20 Jun 2010 15:36 On a sunny day (Sun, 20 Jun 2010 12:29:18 -0700) it happened Perenis <Perenis(a)hereforlongtime.org> wrote in <vlqs16lnmnl33ituigjvbvmapt2f358364(a)4ax.com>: >On Sun, 20 Jun 2010 19:05:42 GMT, Jan Panteltje ><pNaonStpealmtje(a)yahoo.com> wrote: > >>On a sunny day (Sun, 20 Jun 2010 11:59:21 -0700) it happened Perenis >><Perenis(a)hereforlongtime.org> wrote in >><85ps169h4p5qbdcnk77le8j5vg1qk48dpe(a)4ax.com>: >> >>>On Sun, 20 Jun 2010 14:06:54 -0400, Hammy <spam(a)spam.com> wrote: >>> >>>> >>>>>That said, I have wound a TV hor output transformer with normal A4 paper as isolation. >>>>>As long as temperature stays low, and it does not get wet, it works. >>> >>> Only up to about 1000V isolation (that's generous). Without >>>impregnation, that paper looks like it is not even there to the excited >>>electron. Even through several layers of it. D'oh! >> >>Sure, but how much voltage you have between layers if you wind in a normal way >>is something you can calculate. >>1000 V is a lot, much more then was dealing with. >>Say if you have 1 turn per volt, for arguments sake, >>and 100 turns per layer, 3 layers, then there is no problem. >>IIRC I used about 1 turn per volt 440 turns for the H scan coil drive winding >>Long time ago, BW TV, my school days, tubes, worked nicely. > > How many layers did that end up as? > > All it takes to breach the mag wire at the vpt is about 300 turns, so >it also would have to have been flat wound. Can't go that high with a >scatter wind, and regardless of your claim, an overvoltage event would >punch through that like a needle through skin if the lead-out wire (or >turns) are anywhere near the lead-in. Well, for that winding about 5 (with 100 per layer, flat wound). Critical 'overvoltage' events would mean a spot deflection of 3 x teh screen width? Are you dreaming? The HV coil was on a different leg and done in a different way. He is not doing a HV coil (18kV).
From: Perenis on 20 Jun 2010 16:09 On Sun, 20 Jun 2010 19:33:24 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Sun, 20 Jun 2010 15:25:31 -0400) it happened Hammy ><spam(a)spam.com> wrote in <9kqs16p9evdl9lh8ikt3l6uqkg5ecmrnrj(a)4ax.com>: > >>> First, he wants quick and dirty to prove the design. Then, he MIGHT >>>fine tune it, characterize it, or 'dial-it-in'. If it works right on the >>>first jab, he might just be done with it and get back to his other bench >>>work. >> >> >>Exactly. >> >>Thanks for reading the requirments.;-) > >Any mains isolation could be solved by putting windings on separate legs and >using 2 U cores.... >Earth the core. >Safer not possible. It is NOT a line transformer!
From: Cydrome Leader on 20 Jun 2010 16:26 Archimedes' Lever <OneBigLever(a)infiniteseries.org> wrote: > 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. the outside wraps, even the ones around the ferrite halfs can sometimes be peeled off an re-used. the keyword is sometimes.
From: Cydrome Leader on 20 Jun 2010 16:32 Archimedes' Lever <OneBigLever(a)infiniteseries.org> wrote: > On Sun, 20 Jun 2010 06:16:40 +0000 (UTC), Cydrome Leader > <presence(a)MUNGEpanix.com> wrote: > >>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. > > No, I would not. >> >>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. > > Had you read the thread, you would have found that it was already > covered. And the trick is not to "wind many coils". The trick is NOT to > wind too many coils such that the mag wire insulation resistance gets > compromised by the last turn being to near a lower voltage turn, such as > the first or one of the early turns. I'm quite aware of how many tranformers are needed as I was the first person to even ask such a question, before every other expert went off about how to vacuum impregnate a coil. > Also, he is winding ONE unit, not doing a production run, and with small > transformers, especially HV jobs, one at a time is only slightly slower > but yield a far higher prime pass yield. >> >>When done with all of that, you saw or cut the individual windings apart. > > If you wind on a gang, you place several individual bobbins on the > winder, and when you are done, they all come apart just fine. No cutting > and certainly no sawing. So what you're trying to say is you don't know a damn thing about winding transformers without bobbins, which is how how most tranformers used to be made and quite a few still are.
From: Cydrome Leader on 20 Jun 2010 16:35
Perenis <Perenis(a)hereforlongtime.org> wrote: > On Sun, 20 Jun 2010 14:06:54 -0400, Hammy <spam(a)spam.com> wrote: > >>>I am not sure if you can get Melinex in low quantities. >>> >>I'm going to check a couple of motor rewind shops in town see if they >>have the tape But thanks for the suggestion. > > > Much easier to find the current common item, DuPont NOMEX insulating > paper. you really think so? post 3 places that sell nomex paper in small rolls that I can order from in the USA. |