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Grounding an output based on resistance

Discussion in 'General Electronics Discussion' started by alan1977, May 4, 2016.

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  1. alan1977


    Aug 19, 2013
    Good Morning, i have a small project i am trying to get my head around, I have limited electronics knowledge, so i am not too great with the terminology

    Project is this:
    I have a paddle shift steering wheel i wish to fit and control the up and down shifts of a tiptronic gearbox,
    The paddles have a 2 pin connection, the circuit is 270 K Ohm with the switches un activated, press down and the resistance drops to 337 Ohm, press up and the resistance is 1.01 K Ohm.

    The gearbox requires to be put into sport mode (shift to left from drive, grounding sport in addition to drive wires from the gearbox ecu) once in sport mode upshifts and downshifts can be activated by grounding the relevant wire.

    I also have 2 buttons available on my steering wheel which are no longer used, so i had planned to try and incorporate one of those buttons to activate and deactivate sport mode.
    So my plan was this, press the button, which then activates the gear selector circuit and grounds the sport wire, pressing the button again deactivates and isolates the sport pin putting the car back to drive.

    my initial thought were to use a voltage comparator, like an LM393, or 2 lM311 to ground the up/down directly without needing extra transistors. now, the tricky bit is setting up the reference values so that up or down is measured correctly. this is where i am out of my depth.

    am i thinking about this the correct way?
    Thanks, Alan
  2. duke37


    Jan 9, 2011
    You do not say what country you are in. In the UK you would invalidate your insurance and put lives at risk by messing with your car controls.
    I suggest you get a bicycle.:)
  3. alan1977


    Aug 19, 2013
    Thanks for your concern
    i also did not mention if the car was to be used on the road
    i did not mention if i do or do not pay a premium for modified car insurance, there are plenty of vehicle modifications that can be applied legally to a road car which could arguably make the vehicle potentially more dangerous to drive, this is not he scope of my inquiry.

    the vehicle already has the facility to change gear via the gear shift, which requires removing one hand from the wheel, i am trying to do something which is commonly done, however the wheel that is commonly used has seperate outputs for up/down
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