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Coil problems...

Discussion in 'General Electronics Discussion' started by Fred Fredson, Apr 24, 2016.

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  1. Fred Fredson

    Fred Fredson

    Apr 24, 2016
    Hi, :)

    I am new to the forum and not terribly experienced with electronics although a do have a very basic understanding of very simple circuits and have built a few tiny successful projects. I need some advice because something is perplexing me. I am currently building a project where I have to wind a few inductance coils and as such was in need of some magnet wire of a particular gauge (24 gauge to be exact). I was having trouble buying said wire at all and did not like the price or amount I had to buy in bulk to get what I wanted so, I had the bright idea to buy a certain brand of florist's wire, available in the exact gauge I required, as it was economical and claimed to be copper wire coated in enamel just the same as wire used for electronics. I thought this was one of those cases of manufacturers and suppliers over-inflating the price of the same item when it is intended for use for a different purpose.

    Anyway, to cut a long story short, I built my coils and the enamelling seems to be appropriately insulating and easily removed just like on magnet wire, however, I tested the resistance of several of the coil taps which are only a few feet long each (say 5-6 feet), to find to my severe irritation and bewilderment that I was getting readings in the high Mega-ohms region.

    Now, perhaps I was stupid and naive to have tried to save money buying florist's wire but I cannot understand the readings I am getting. If we believe the manufacturers that it is actually mostly copper then the readings make no sense because copper is copper full stop and has to behave like... well... copper and should be showing much better conductance. If we assume a lie or bent truth on the part of the manufacturers and assume that the wire is either an alloy with low copper content or in fact another metal entirely then I am still confused. I looked up the conductivity of metal after metal in a big chart and could not find anything that matched the sheer resistance of whatever weird wire I have for it's length and gauge. Even resistance wire used for heating and the like is apparently a better conductor than whatever I have... I am very confused. I can only assume what I have is not even metal!! But I think I recognise metal when I see it... it has all the properties one associates with metals. It's shiny and somewhat malleable and so on and looks and behaves just like metal.

    I have tried a second multimeter just in case my first one was in error but get the same readings. I have also made absolute sure that the enamel is fully removed from the ends of the wire I am using as contact points. If anyone can tell me what is going on here and how is this even possible I would be greatly obliged. Is there a metal with such low conductivity? :)
  2. Arouse1973

    Arouse1973 Adam

    Dec 18, 2013
    Hi Fred. Welcome to E.P. I thought Florist wire was aluminium is it is it won't be suitable for winding coils. However the resistance would indicate you have not scraped the coating off properly or the multi meter is not set up correctly.
    Fred Fredson likes this.
  3. Colin Mitchell

    Colin Mitchell

    Aug 31, 2014
    To check the resistance, cut 1 metre of wire and connect it to the terminals of the battery in your car. Hold it with pliers and watch it glow red and go up in smoke.
    Fred Fredson likes this.
  4. Minder


    Apr 24, 2015
    Did you try a local motor winding shop, they will often oblige with end of roll qty etc.
    Also i have found deals on ebay in the past.
    Fred Fredson likes this.
  5. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    Commonly, floral wire was made from painted soft-iron wire because of cost and malleability considerations. Please see if a small permanent magnet will attract the wire you have. If so, it is iron wire.

    However, I agree with @Arouse1973 that you may not have removed the insulation sufficiently. Even iron wire would show a low resistance at the lengths you mentioned.

    Also, buy some enamel-insulated copper wire from eBay for your coils. Using floral wire is penny-wise but pound-foolish, even if you don't count the cost of your time.
    Last edited: Apr 25, 2016
    Fred Fredson and dorke like this.
  6. dorke


    Jun 20, 2015
    your ebay link goes to Antennas...;)
    Fred Fredson likes this.
  7. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    Thanks. That link was from a woo-woo reply on Moebius loops. It's fixed now.
    Fred Fredson likes this.
  8. duke37


    Jan 9, 2011
    Modern wire will possibly have self fluxing wire so you could 'tin' the end of the wire or could use a candle to clear the insulation. Try to measure the resistance of an inch or so of the wire, that will tell you if you have a good connection.
    Some wires are double coated so a change in colour will not ensure that all insulation is removed.
    Arouse1973 and Fred Fredson like this.
  9. Fred Fredson

    Fred Fredson

    Apr 24, 2016
    Hi, Everyone! Wow! What great friendly forum full of knowledgeable people! Thanks so much for all the advice I will try your suggestions and report back with results. The wire does SAY it is copper but to what extent we can believe the manufacturers' claims is anyone's guess. I will have to locate a magnet and and also something to make a flame with. :) I have discovered I can get magnet wire of the right gauge that I need at a local electronics store for a reasonable price so, it might might be just as well to buy some of that. It's not in pretty colours like the wire I had which is a bummer because this part of the circuit will be on display and would have looked cool... but I suppose it's more important that it work. :)
  10. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    Well, electronics is very much an art. So get out your air-brush and "touch up" the finished project to your taste.
    Arouse1973 likes this.
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