limiting DC current

Discussion in 'General Electronics Chat' started by raidermanz, Aug 16, 2007.

  1. raidermanz

    Thread Starter Active Member

    Aug 14, 2007
    I am new to the electronics world, so please forgive my ignorance, I have a mechanical design background so please respond in "little steps":confused:

    I have a heating element which will be powered by a 24vdc power supply, at this time, I am not sure what max current I will be getting, however for this question, let's assume that I have 2A available to the heater. From this same power supply, I would like to power an assortment of low consumption devices. My heater is such that it pulls as much current as I can provide to it when it is below it's rated temperature, and the current draw reduces proportionately as the temperature of the device climbs. I would like to limit the maximum current to the heater to 1.5A.

    I am probably missing an obvious solution, but please refer to the first sentence of my post.

    Thank you for any and all suggestions
  2. John Luciani

    AAC Fanatic!

    Apr 3, 2007
    Take a look at the TI TL431 datasheet. There is a current limiter circuit and a current
    sink circuit. Each circuit consists of a TL431, 2 resistors and q power transistor.
    Either circuit will work in your application. Make sure you calculate the power
    dissipation of the high current resistor and power transistor.

    (* jcl *)
  3. raidermanz

    Thread Starter Active Member

    Aug 14, 2007
    Thank you very much.
  4. mrmeval

    AAC Fanatic!

    Jun 30, 2006
  5. davefromnj

    New Member

    Oct 14, 2008
    Use a properly rated PTC Thermister in series with the load.