Construction Relay

Discussion in 'The Projects Forum' started by Jimmie, Mar 14, 2008.

  1. Jimmie

    Thread Starter New Member

    Mar 14, 2008
    I want to make a simple relay. 12/24VDC to be opreated at currents exeeding 450 mA/160 mA,. The required size is diameter 11 mm Length about 26 mm. What dia coil to be used and the number of turns required. Can any body help me? Thanks
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    I've moved this into its own thread to avoid confusion discussing two similar, but distinct topics. The other thread dealt with an existing relay as part of an existing circuit whereas this one deals with building a relay from scratch.
  3. SgtWookie


    Jul 17, 2007
    Single pole, single throw, normally open? Or something else?

    The contacts, you mean? Or the coil?

    Is that the maximum size in all directions, or your coil size limitations?
  4. SgtWookie


    Jul 17, 2007
    Here are some numbers for you...
    If you took a 3/16" O.D. tube form 3/4" long, and wound on 2,700 turns of #36 wire (about 129 turns/layer, 20 layers) and it will take about 220 feet of wire.

    The resulting coil will measure about 90.5 Ohms, drawing about 265mA @ 24V, and 133mA @ 12V, and have about 19.5mH inductance prior to adding the solenoid rod.

    Or, you could use about 4000 turns of #38 wire on the same form, about 25 layers, 156 turns/layer, 325 feet of wire. That would measure around 214 Ohms, drawing 112mA@24V, 56mA@12V - and would run quite a bit cooler. This 2nd coil would have 43mH inductance prior to adding the solenoid rod.