Build A Transformer - Need Help

Discussion in 'The Projects Forum' started by Mike Mandaville, May 27, 2009.

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  1. Mike Mandaville

    Thread Starter Active Member

    May 27, 2009
    Okay, so first I went down to the Home Depot, and bought a roll of tie wire, and a roll of electrical tape. I wrapped a layer of tape around the tie wire, and then I wired the result into the frame of an old typewriter desk, using thirteen individual pieces of tie wire altogether, from another roll of tie wire, so that this doughnut is rock solid in the frame.

    I tore an extension cord apart, and began wrapping the extension cord wire around the tie wire. I was able to get forty turns on the first layer, and I made a tap at that point. Then I wrapped another layer of tape around the tie wire, and another layer of extension chord wire around the tie wire. I continued this process until I had three layers of extension cord wire wrapped around the tie wire, which gave me one-hundred-and-ten turns of extension cord wire altogether.

    After that, I hooked up an extension cord to the ends of the coil, and then I hooked up a lamp to the tap, and to the end of the coil which gave me forty turns for the lamp circuit altogether.

    Okay, so when I plug this transformer in, the one-hundred watt bulb lights up like a forty watt bulb would for a few seconds, but then the fuse blows.

    Obviously this transformer is drawing too much current. Can somebody tell me why?

    Thank You.
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    My only comment is that this is incredibly dangerous.
  3. SgtWookie


    Jul 17, 2007
    Please discontinue your line-powered transformer experiment. It's very unsafe.

    Small line-powered step-down transformers use laminated steel cores. The metal is a special formulation.

    You're using the wrong type of wire, and no transformer core. With no core, you would need a tremendous number of turns.

    Air-core transformers are used for higher frequencies (in the MHz range), but at 50 to 60 Hz, they act nearly as straight pieces of wire. Basically, you're just shorting out the mains.

    There is a lot of engineering that goes into making transformers safe and efficient. Your project is neither safe nor efficient.

    Please obtain a commercially available step-down transformer, and experiment with the low voltage secondary. Use a 2A or less fuse on the primary side.

    Electrical "newbies" should keep their experiments under 45v. Safety is the most important consideration.
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009

    You are one curios or crazy tech. Meddling with the mains voltage without a laminated core, did anything smoked. :D

    I like what you are doing since like when I was around 12, I found out when you short out 1.5V cells I get a spark, so I tried to see what happens when I short 220V mains. so I took out two wires wrap it around the fan plug, plugged it in and shorted the wires ( thank god I was not stupid enuf to hold the bare wire :) ) and BAAAAAAAAAAAAAAAAAAAAANG!!!!
    :eek: well! you can guess where I ended up.
    I got the beating of a lifetime from my dad :D
    Last edited: May 27, 2009
  5. Mike Mandaville

    Thread Starter Active Member

    May 27, 2009
    Since you obviously don't know why my transformer is drawing too much current, why don't you just say so? Nothing is dangerous without there being a reason, and since you have not given a reason, how do you expect to be taken seriously? You obviously are using a pseudonym, and are issuing your "only comment". Is that because any further comment would be difficult for you to back up? If I thought this experiment was dangerous, I never would have done it in the first place. This house was wired by my grandfather, who wired many houses during his many years as a builder. You never knew my grandfather. You are not qualified to evaluate his skill as an electrician.
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    woah there buddy. Relax. Everyone knows why you tx is drawing too much current.
    It's cause the core is not strong enuf to oppose the primary current, or the primary winding's series resistance is too low.
    On the other hand if the wires can withstand the amount of I drawn then I suggest you beef up your CB to a high amperage.
    and may be trip the CB in the power station :D
  7. beenthere

    Retired Moderator

    Apr 20, 2004
    When one flys straight into building a device with absolutely no background knowledge, the results can be as simple as a blown fuse, or as terminal as a burned down house or personal harm to the ignorant experimenter. You are very lucky to have come out of this unharmed. What you did was incredibly dangerous, even though you were unaware of it.

    You really need to take the time to read about electronics (and transformer theory) before trying to flange anything else together.
  8. KL7AJ

    AAC Fanatic!

    Nov 4, 2008

    Now Sarge:

    Ya gotta give the guy some credit.....he actually got the bulb lit! :D

    This is the sort of thing that plasma physics labs are made of. :)

  9. Mike Mandaville

    Thread Starter Active Member

    May 27, 2009
    Sergeant, please demonstrate that these experiments are unsafe. You have _labeled_ them as "unsafe", but until you _demonstrate_ them as unsafe, I cannot comply with your request. Surely you must have a reason, or you would never have made the request in the first place.

    You must have forgotten to count this one. It's made out of iron. And it weighs three-and-one-half pounds.

    I consider iron to be even more special. It makes a better magnet.

    You are adept at labeling, and then not giving a reason. I am equally adept at rejecting labels where no reason is given.

    Again, the core is iron.

    Yes, but I do have a core

    Well, if I was making an air-core transformer, that explanation might make sense. However, I am not making an air-core transformer, so that explanation makes no sense.

    If my transformer was efficient, I never would have posted here in the first place. That my project is unsafe has not been demonstrated.

    Sorry, but I am unconvinced.

    Sergeant, for your information, I studied electronics at the Marine Core Recruit Depot in San Diego.
  10. StayatHomeElectronics

    Distinguished Member

    Sep 25, 2008
    Are all of the turns connected together with a tap being on the 40th of 110 turns? Or, is there isolation between two sets of turns? Can you post a simple diagram of the system to the forum?
  11. PRS

    Well-Known Member

    Aug 24, 2008
    I once made an electro magnet by winding over 100 turns of #24 enameled wire around a 16 penny nail driven into a block of wood. I connected it to a 120 volt outlet and man was that magnet strong!
  12. bertus


    Apr 5, 2008
  13. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    Man 'o' man ..I like this guy..
    Hey Mike..why do u prefer iron to laminated core.
    did u know iron core loss is very high
  14. Bernard

    AAC Fanatic!

    Aug 7, 2008
    If you want a slightly better core: Wind a torid from strapping steel, 1/2 or 3/4 in wide, with enough turns to give about .4 sq. in cross-section. Wind with 2.5 turns/volt over well insulated core. Core diameter around 2.5 in. OD. It worked in 1967, might work today.
  15. SgtWookie


    Jul 17, 2007
    OK, the first thing is that you're using the wrong type of wire. You should have been using "magnet wire" of the correct gauge. The stuff used to be coated with enamel or lacquer, but nowadays it's all synthetic materials. The trouble with using the kinds of wire you did is:
    1) The insulation is "electrical tape". Electricians don't use "electrical tape" as insulation; when it's heated the glue softens and the tape falls off. You will wind up with a bare wire and direct exposure to mains voltage, likely zapping you and/or causing death.
    2) The insulation is too thick. This keeps the heat inside the wire, rather than allowing it to dissipate.
    3) The lamp wire is stranded, not solid. This adds to the bulk.

    OK, you didn't specify that you actually DID have some kind of a core. However, what you used certainly was not designed for your intended application.
    Even plain iron magnets aren't very good at being magnets. There's usually some nickel and/or cobalt thrown in the mix at least. Ever wonder where the name "Alnico" came from?

    A transformer is a whole 'nother animal from your typical fixed magnet. The cores are laminated to keep eddy currents minimized, there is frequently some silicon added, and the formulation is different from that of plain magnets. Here's a decent introductory page to various types of transformer cores:
    Note that "E"-type cores are the ones most frequently encountered for small to moderate-sized mains transformers; efficient and low EMF radiation. Toroidal core transformers are extremely popular for their efficiency and low EMF radiation over a wide range of frequencies.

    See the above.

    OK, frankly I did wonder how you got any kind of output at all. The fact that you DID have some kind of iron/steel core in there kept things from getting ridiculously out of hand.

    Mike, you're using the wrong type of wire.
    Use solid core wire that's enameled (generic term). KAPTON insulation is tempting, but don't use it - NAV/MC banned it's use on aircraft in the mid 80's due to numerous accidents.

    Ahh, I graduated Boot from there. So, you're a MOS 2841? Didn't you spend time at 29 Stumps?
    Did you complete the Navy NEETS course?
    It's available online here:
    I completed a predecessor course called AFTA (Advanced First Term Avionics) at NAS Memphis. I was MOS 6657.

    We have to be rather cautious around here, as most 1st-time posters have experience that's limited to plugging an appliance into an outlet. We want people to come back, which is doggone difficult if they get killed. :p

    Not knowing anything about your level of training or experience, the error was made on the side of caution. You should appreciate that.

    But seriously, there IS a good bit of engineering that goes into designing a safe, efficient and low-EMF emission transformer. I don't bother with it, because there is such a variety of them on the market that can be purchased quite inexpensively. If you can find one even close to your intended application, you're way ahead of the game - rather than trying to manufacture one by yourself.

    Thanks for your Service.
    Last edited: May 27, 2009
  16. Mike Mandaville

    Thread Starter Active Member

    May 27, 2009
    Here is a Maldivian arc welder:

    laminations cut from scrap sheet steel, paper slips between the laminations, and string to tie the assembly together.

    Last edited: May 28, 2009
  17. Mike Mandaville

    Thread Starter Active Member

    May 27, 2009
  18. Wendy


    Mar 24, 2008
    Ya gotta love it. Can this arrangement work continously?
  19. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    You gotta be kiddin me :eek::eek:

    was that transformer you build. :eek:

    No wonder the you got excess primary current. You have got like laminated air core or some thing like it.....that core will have a lot of eddy current.
    kekekekeke :rolleyes::rolleyes::rolleyes:
  20. Mike Mandaville

    Thread Starter Active Member

    May 27, 2009
    No results found for flys:
    Did you mean flays (in dictionary) or FLS (in reference)?
    Dictionary suggestions:Reference suggestions:flaysFLSfleysFlyfly'sLysFLSFLLSLysFLOSflyFLDSlysFLHSfaysFLVSfoysFly!flu'sFly.lys-Flyifay'sFrysfays'Fly2Kfoy'sFry'sfoys'F.L.Yfry'sF.L.Y.ply'sFly540fl ysFly 540fl-ysFay's 150
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    When one posts with a pseudonym, one will not always be taken seriously.
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