Resistance Detector, control various functions.

Thread Starter

REBinc

Joined Nov 17, 2009
2
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?
 

russ_hensel

Joined Jan 11, 2009
825
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.
 

Dan-O

Joined Jul 26, 2009
38
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:
http://www.madhacker.org/carbuttons.htm
 
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