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Coils

Discussion in 'Electronic Basics' started by Chiron, Jan 26, 2012.

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  1. Chiron

    Chiron Guest

    I've wanted to check out some things using big coils - not the sort used
    for RF circuits, but large coils such as might be found in a Tesla coil.
    I don't have the funds to special order them or to buy them pre-made
    (assuming they even come that way). I expect I'll have to wind my own...
    but...

    How the heck do you do that? What sort of arrangement would work for
    that? Trying it by hand left me exhausted and with poorly-wound coils of
    insufficient turns. Surely there is some simple arrangement whereby you
    can feed in wire and magically get out coils.

    Can anyone point me in the right direction with this? I'd appreciate
    it. I've already tried Google, with little success.

    I also tried buying a used "coil-winding machine," but it's just a
    powerful motor with a chuck for holding the coil's form. No speed
    control at all, no reasonable controls. There is a toggle switch that
    selects the motors direction, and doesn't even let you turn the damned
    thing off. If it's plugged in, it's rotating one way or the other at
    full speed and power.

    I'd appreciate any helpful ideas. Thanks.
     
  2. Randy Day

    Randy Day Guest

    Googling on 'diy testla coil' brought up:

    http://www.rmcybernetics.com/projects/DIY_Devices/homemade_tesla_coil.htm

    Car ignition coils from a scrapyard are
    one option.
     
  3. Chiron

    Chiron Guest


    Thanks, Randy. However, I am not particularly interested in making a
    Tesla coil; I simply mentioned that to give an idea of the types of coils
    I was interested in creating. Big coils, lots of windings, air core,
    potentially very high voltages and relatively high frequencies. Some
    with fairly high magnetic flux density, perhaps. I am looking for
    flexibility.

    I've used ignition coils previously, which are OK for some uses.
    Unfortunately, they are limited. IIRC, they have an iron core which
    limits their upper frequencies.

    The solution, as I see it, is to wind my own coils so that I can choose
    their size, wire gauge, number of turns, core, and other variables.
     
  4. Chiron

    Chiron Guest

    On Thu, 26 Jan 2012 18:28:58 -0600, John Fields wrote:

    I want to wind coils. That is what I want to do.

    I don't want to *have* coils, per se; I want to *wind* my own coils, so
    that I can adjust them for whatever variables seem interesting,
    necessary, or otherwise useful.

    I do not have in mind any particular project to build. I want to putter
    around with them, as my interests may lead me. So maybe I'll want a
    large magnet; or a transformer of some sort; or a Tesla coil, Oudin coil,
    hell, I don't know, maybe even motor windings.

    Maybe think of it as a sort of "teach me to fish" kind of thing. Instead
    of needing to track down this kind of coil, or that kind, I'd be able to
    make whatever I needed.
     
  5. Winston

    Winston Guest



    Look at 0:06 and starting at 1:02.

    See how he's adapted a cable to allow foot
    control of the motor speed?

    As soon as I saw that I thought "Coil Winder"!

    The Foredom FCT-1 is an electronic solution
    that would plug right in without any
    'metalworking heroics'.

    Nifty!

    --Winston
     
  6. Chiron

    Chiron Guest


    Thanks, George. Maybe I can work something out with this motor I've got
    (the alleged "coil winder." Its one advantage is that it already has a
    counter on it. I think a foot-operated switch would be a great idea.

    I wonder whether there is any sort of foot-operated switch that lets you
    adjust the speed... that would be a major help, since this motor turns
    faster than I can feed in wire (10,000 RPM).

    I've been seeing people talking about PWM. I've never worked with that,
    but it might be something to try for the motor.
     
  7. Chiron

    Chiron Guest


    Thanks, Winston. That sort of foot-operated switch, that allows variable
    speeds, sounds perfect.

    The guy who made the video seems very inventive.
     
  8. Chiron

    Chiron Guest

    <snip>

    Wow! Thanks, "default," whoever you are. You've given me some great
    ideas to try. I appreciate it.
     
  9. Winston

    Winston Guest

    Chiron wrote:

    (...)
    Yup, just plug one of these in and tyrap your trigger to 'constant ON'.
    Only nine are available here, but they cost only 30.50 each! http://tiny.cc/3q4in

    He does very nice work.

    --Winston
     
  10. asdf

    asdf Guest

    I stumbled upon some homemade coil winding machines projects just by
    looking for coil/inductor formers, winding, etc on google. Didn't save
    the links but they sprung out pretty easily.
     
  11. This is the method I preferred. You can wind a coil by hand faster than
    you can around talking about it, or waste time making some contraption.

    The largest coil I made was about 5' long on 10" PVC pipe.

    The trick is to not stop once you start winding, and to tape the edges
    down if you do take a break so you don't lose tension in the winding. If
    it unravels when you wind it, you're screwed. Cut the wire off and start
    over.

    Don't wind magnet wire on warm PVC either. PVC shrinks enough in the cold
    for the windings to loosen and slip over each other.

    Winding a secondary coil is one of the easier tasks in making a tesla
    coil. Once you make it you're done- all the other parts including the
    primary require lots of fiddling with.

    I'm not sure what size coils you want, but I've always liked 20 guage
    copper. It's strong enough to not tear and thick enough wide edgewise with
    a wooden block to force the windings down and next to each other as you
    turn your coil form. I've wound coils by throwing a PVC pipe on some felt
    over an open dresser drawer with a spool of wire on the other side of the
    room. The front edge of the drawer keeps the coil from rolling away. Save
    the energy wasted on rube goldberg winding machines for your spark gap.
     
  12. Jasen Betts

    Jasen Betts Guest

    mount a chuck on the back wheel of a domestic sewing machine,
     
  13. Chiron

    Chiron Guest

  14. Chiron

    Chiron Guest

    On Fri, 27 Jan 2012 12:33:47 -0800, George Herold wrote:

    I'm sure there's some way to do it, but I'm not sure *I* could do it.
    I'm not mechanically gifted.

    I really got taken with this "coil winder," I think. It's mostly just a
    fast, powerful (1/7 HP) motor on a platform, with a chuck and a counter.
    I cannot imagine how anyone could have used the thing for winding coils.
    OTOH, it *is* a nice, big motor that could probably be useful for
    something. Maybe a Van de Graaff generator or something...
     
  15. Guest

    Since the motor is a 10,000 rpm motor I assume it is either a DC motor
    or a "universal" motor. Like a drill motor. I have used lamp dimmers
    on these types of motors. Properly rated for the current the motor
    draws they work well and are cheap. And they are PWM devices so the
    torque will stay pretty constant. Even though the cheap ones are made
    for resistive loads only according to the package I have never had one
    fail prematurely.
    Eric
     
  16. Guest

    Whoops! You're right Jamie. The cheap ones are as you describe. I do
    have some 12 volt PWM motor controllers that I built myself from kits
    and was thinking of those. Nevertheless, the cheap lamp dimmers do
    work pretty well for controlling the speed of universal motors.
    Thanks,
    Eric
     
  17. Winston

    Winston Guest

    And see how this guy uses a cheap calculator
    as a turns counter?! Genius!



    --Winston
     
  18. That sort of thing wasn't uncommon 35 years ago, once there were cheap
    calculators. One could also use a pedometer, now made cheap since they've
    become faddish, and thus available in cereal and garage sales.

    Of course, one could just strip an old cassette deck, and use the counter
    from that, so long as one could properly connect it to the rest of the
    mechanism.

    Michael
     
  19. Winston

    Winston Guest

    I bought a couple for just that use. Unfortunately they stop working
    properly at lower battery voltage and the 'calculator' solution yields
    a unit with a larger display anyway.
    Thassa lot of work. I'd go as far as putting an opto interrupter
    wired across the "=" key of a dollar store calculator but not
    much more. :)

    --Winston
     
  20. Winston

    Winston Guest

    Wow! I was just getting used to the ultra-fine divisions in regular
    encoder wheels and you show me an apparatus with sub-wavelength
    resolution! Incredible!

    --Winston
     
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