Resistance Detector, control various functions.

Discussion in 'The Projects Forum' started by REBinc, Nov 17, 2009.

  1. REBinc

    Thread Starter New Member

    Nov 17, 2009
    What I would like to do it build is a project that detects a resistance, and then according to that resistance chooses between 4 different functions.

    For example:
    80ohm = lock doors
    150ohm = unlock doors
    240ohm = traction control off
    300 ohm = vcs off

    The problem is I want to use controls on my steering wheel, but it's output is only two leads, that vary in resistance depending on what button is pressed. I originally was going to send 12v accross it, and then use different amperage rating transistors as switches that would only trip according to a certain resistance, but the problem with that is a low resistance will produce a high current that will also trip all the smaller transistors.

    Is there anything out there I can use?
  2. russ_hensel

    Distinguished Member

    Jan 11, 2009
    Use an analog to digital converter. The input would be from a voltage divider using one of your resistors as one of the legs. Using a uController like the Arduino you get the converter and enough processing power to decide what to do with the reading.
  3. REBinc

    Thread Starter New Member

    Nov 17, 2009
    Thanks, the Ardiuno looks really promising. It will take me a little bit to look over all of it, but I'm sure I'll have more questions.
    This is looking perfect:

    I ordered two, I'll update once I can mess around with them a little.
    Last edited: Nov 18, 2009
  4. MikeML

    AAC Fanatic!

    Oct 2, 2009
    LM3914, where the resistor network selects between output steps.
  5. Dan-O

    Active Member

    Jul 26, 2009
    Ooo, I like the LM3914 idea, cheap, simple and effective.
    The output could drive a transistor and it's good to go.
    I stepped in because of my pushbutton start project. GM uses a nice rocker switch that is 2 different resistance values for the functions.

    I also found this:
    Last edited: Nov 21, 2009