What's that yellow stuff around transformers?

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Discussion Overview

The discussion revolves around finding suitable materials to wrap around the coil of a bottle radio to prevent the magnet wire from unwinding. Participants explore various alternatives to lacquer, considering factors such as ease of use, cost, and safety for a demonstration aimed at children.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests using translucent tape instead of lacquer, expressing concerns about the mess and drying time associated with lacquer.
  • Another participant identifies the yellow material as a plastic film insulation that separates the windings from the environment, recommending PVC tape or clear sticky tape for low voltage applications.
  • A different viewpoint highlights that the yellow tape can handle high temperatures, proposing various alternatives like hair spray, cling film, or hot glue, given the low heat and voltage of the device.
  • Mylar tape is mentioned as a common name for the yellow tape, noted for its good electrical properties and low cost. The process of varnishing transformers is also described, including the use of vacuum to ensure penetration and subsequent baking to harden the varnish.
  • One participant shares personal experience using woodworker's polyurethane varnish and engine enamel for electric motor windings, noting the quicker drying time of engine enamel but its less appealing colors.

Areas of Agreement / Disagreement

Participants present multiple competing views on suitable materials, with no consensus reached on a single best option for wrapping the coil.

Contextual Notes

Some suggestions may depend on specific conditions such as temperature and voltage, and the effectiveness of alternatives like hair spray or cling film remains uncertain.

Who May Find This Useful

This discussion may be useful for hobbyists, educators, or anyone interested in DIY electronics, particularly in the context of low-voltage applications and safe materials for demonstrations.

BeautifulLight
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transformer.JPG

I need to find something that I can wrap around the coil of a bottle radio (image below) to keep the magnet wire from unwinding. Lacquer is messy and time-consuming. I'm hoping there is a translucent tape that I can use? Someone suggested using Kapton tape, but it's very expensive and a bit overkill for my application. Maybe I can find a generic roll on ebay. I'm going to be showing how to make crystal receivers to kids (ages 7-11). I'd rather not use lacquer (fumes and drying time). Suggestions?

bottle radio.jpg
 
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The yellow stuff is a plastic film insulation that separates the outer windings from the immediate environment.
PVC tape or clear sticky tape would work OK as the voltages involved are very low.
http://en.wikipedia.org/wiki/Sellotape
 
I think the special characteristic of that yellow tape is that it can handle high temperatures.
Since your device won't get hot or handle high voltage , I think you could use anything you've got at hand, mums hair spray, spray paint , cling-film, hot glue, any glue ,sellotape ...
 
The yellow stuff is commonly called Mylar tape, Mylar being a trade name owned by Dupont. It is a polyester tape with good electrical properties and low cost.
Transformers are also dipped in a bucket of varnish and a vacuum is drawn on the transformers and varnish causing the varnish to penetrate into crevices.
Afterwards, the transformers are restored to atmospheric pressure and placed into an oven where the varnish bakes into a hard substance that protects the transformer and discourages any vibration.

I suspect there's a number of varnishes that are solvent based (just allow the solvent to dry away) Perhaps some guys on the Tesla Ring will have a suggestion.

- Mike
 
I have used woodworker's polyurethane varnish on electric motor windings.
Also engine enamel in spray cans from the auto parts store. The engine enamel dries quicker but the colors tend to be garish,,,
 

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