Making a solenoid

Discussion in 'General Electronics Chat' started by stoopkid, May 30, 2013.

  1. stoopkid

    Thread Starter Member

    Mar 3, 2011
    I need a bunch of solenoids for a small organ and I can't afford to spend a few dollars on each one so I'm trying to make my own. I've got a pretty nice thing going with a plastic bobbin and 30 gauge magnet wire.

    My question is, what is the best way to get some good actuation and power out of it in terms of permanent magnet placement and size? Does having a longer magnet to pass through the center increase the power/actuation? In other words, would having say a 12 inch magnet bar to pass through it cause the magnet to want to pass all the way from one end to the other with a consistent strength or would I be trading actuation for power? Does length not matter aside from it's overall power?

    I'm not trying to get 12 inch actuation, I just want to know what to look for to get the most power. I shouldn't need any more than a centimeter of actuation and even that would be a lot. The inside of the bobbin is exactly 1/4" by just under 1/2".

    In other words, does the magnet want to pass through or to align? I suppose now that I phrase it that way it's pretty obvious that it wants to align or else you'd have a perpetual motion device. So should I be terribly concerned about the length?

    Thanks for any info

    Edit: ok after some more experimenting my new question is, which would get me more power over about a cenimeter: a long piece of metal or a very short piece of magnet?
    Last edited: May 30, 2013
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    You dont need a magnet just a piece of soft iron bar that fits inside the former, so it moves in/out when voltage is applied, put a spring at one end to push it back.
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
    Look at SN: G 19070, Electronic Goldmine; 12V solenoid, 14Ω, US $ 1.49
  4. Rbeckett


    Sep 3, 2010
    In order to increase the strength you need more wraps on the bobbin with a thinner gauge wire. The more wraps the more dense the magnetic field will be when activated. There is a trade off and at some point there will be a diminishing return on additional wraps, but you are probably a long way from there yet. Radio Shack sells the magnet winding wire that is coated so you can get more wraps in less area, that is definitely a good starting point anyway. Hope this helps.

    Wheelchair Bob
  5. shortbus

    AAC Fanatic!

    Sep 30, 2009
    Also solenoids are better at pulling than pushing. A push type solenoid is harder to make, due to the need to have a nonmetallic rod with a iron head on it.