need to activate switch on application of wide ranging voltage (dc) and current

Discussion in 'The Projects Forum' started by dogfuel, May 4, 2010.

  1. dogfuel

    Thread Starter Member

    Apr 13, 2009
    I'm not proud so feel free to laugh at my ignorance ...

    I need to close (or open) a switch upon the application or removal of a dc signal. If possible, I need to accommodate a wide range of voltages in the trigger signal 3.3 - 24v and an equally wide range of currents (from a few milliamps to 1 amp).

    If the trigger signal was constant, I'd use a transistor or ss relay (I can put 3v over the target switch if needed) but have no idea how to do this for an unknown signal. A reed relay?

    Thanks in advance
  2. mik3

    Senior Member

    Feb 4, 2008
    Where is this signal coming from?

    You can use a comparator IC supplied by 24V DC and when the input voltage is above 3.3V it will control a relay (if its output current rating allows) or something.
  3. Engr


    Mar 17, 2010
    do you have a schematic diagram for this? You can try using a mosfet with a high current rating and a Vgs => 3.3V
    dogfuel likes this.
  4. dogfuel

    Thread Starter Member

    Apr 13, 2009
    this is a general purpose input - it could be anything from an analog sensor 4-20ma (converted to 0v or voltage) to the electrical system of a piece of equipment. It may be impractical to do this but I'd like to covert 0v and any voltage at any current to a binary value by opening or closing a switch.
  5. Bychon


    Mar 12, 2010
    This description makes it even less likely that anyone can guess what you need.
  6. retched

    AAC Fanatic!

    Dec 5, 2009
    If you want to convert a 0 to a 1, use an inverter, or Schmitt trigger.

    I am taking a guess here, but Im guessing the thing sending the signal is usually outputting 0v and when it outputs something other than 0v you want to operate a switch?

    Will a relay do?

    a LOT more info on your part would be helpful.