Hi, I wonder if you guys has any experience with re-taping the outer layer of insulation/protection tape on toroidal transformers, diy-style. What I can read is that it’s usually polyester or mylar tape used.
1. What tape to use, where to get it
2. How the **** to get the tape roll through the hole X times. I mean unrolling the entire length needed is undoable. Is there this tape in very small rolls, or how would one do it?
I have some nice working donuts but tape is falling off. I also have some that I am thinking of cutting away outer layer, re-dip in varnish and re-tape. They have a small gurgling noice that I don’t think is because of to few primary turns but rater bad varnish/slightly vibrating secondaries.
1. What tape to use, where to get it
2. How the **** to get the tape roll through the hole X times. I mean unrolling the entire length needed is undoable. Is there this tape in very small rolls, or how would one do it?
I have some nice working donuts but tape is falling off. I also have some that I am thinking of cutting away outer layer, re-dip in varnish and re-tape. They have a small gurgling noice that I don’t think is because of to few primary turns but rater bad varnish/slightly vibrating secondaries.
If nonadhesive tape is used, put it on the same shuttle used for winding the wire. I still haven’t found a good source for this, but can get some pretty long pieces from other commodity products. The last few rolls of foam weatherstripping I bought came with that tape as a backer. Of course I saved it for transformer use. The same tape is used to wrap the wires in Armorlite cable - and Ive gotten quite a bit when I wired my shop. I’ll get more from wiring the house…..
If an adhesive tape is used, simply squash the roll flat. You may not be able to use full rolls on smaller trafos, but a full 72 yard roll goes through a 1 or1.5 kVA just fine. 3M 1350 is rated for transformer use - it’s the stuff used to insulate between layers and the outside of SMPS trafos. I use it on EI’s and toroids.
If an adhesive tape is used, simply squash the roll flat. You may not be able to use full rolls on smaller trafos, but a full 72 yard roll goes through a 1 or1.5 kVA just fine. 3M 1350 is rated for transformer use - it’s the stuff used to insulate between layers and the outside of SMPS trafos. I use it on EI’s and toroids.
Kapton (polyimide) is your friend for this sort of application as it withstands much higher temperatures than many materials.
BTW Mylar is a brandname for a polyester. Also there is Nomex which is commonly used for motor and transformer insulation (and is good at high temperatures too).
You definitely don't want a tape material than isn't flame-resistant, that's a recipe for disaster.
You may well need to re-reel the tape onto a small diameter tube to use for a toroid. Toroid winding machines may use specialist reels - no idea where to look.
BTW Mylar is a brandname for a polyester. Also there is Nomex which is commonly used for motor and transformer insulation (and is good at high temperatures too).
You definitely don't want a tape material than isn't flame-resistant, that's a recipe for disaster.
You may well need to re-reel the tape onto a small diameter tube to use for a toroid. Toroid winding machines may use specialist reels - no idea where to look.
Back in the 80’s 3M #56 tape was used. It’s not UL 94V-0 but it does meet some standards. Good to 130 deg. C.
There are better tapes (3M #27) but these are thicker and very expensive. There was a 94V-0 tape from 3M that was like #56 but was white instead of yellow (#10 maybe) but I couldn’t find it at the usual sources.
For manual taping of toroids we’d take a piece of G10 fiberglass board about 3-6” long and a width of less than the transformer coil inner diameter. We’d load up the G10 stick by wrapping it lengthwise with many turns of tape. Then we’d start taping the coil by hand dropping the stick down through the centre of the coil each time.
Always make sure to overlap the tape by 2/3 on the outer part of the wrap.
It’s as tedious as f&$k but it works.
There are better tapes (3M #27) but these are thicker and very expensive. There was a 94V-0 tape from 3M that was like #56 but was white instead of yellow (#10 maybe) but I couldn’t find it at the usual sources.
For manual taping of toroids we’d take a piece of G10 fiberglass board about 3-6” long and a width of less than the transformer coil inner diameter. We’d load up the G10 stick by wrapping it lengthwise with many turns of tape. Then we’d start taping the coil by hand dropping the stick down through the centre of the coil each time.
Always make sure to overlap the tape by 2/3 on the outer part of the wrap.
It’s as tedious as f&$k but it works.