Gear shift knob Using Force sensitive resistors

Hi Guys.

Pretty new to electronics like this, but reasonably familiar with automotive electronics.

I am looking at building a gear knob which has 2 x FSR’s front and back and using the output from these into a voltage divider to activate a 0-5v shift cut function in my programmable Engine ECU,
So every time i apply force to shift gear it will hopefully be sensitive enough to give me a clean signal my ecu can detect.

One of my questions is whether i can run the 2 x sensors i want to run in parallel into a single voltage divider. as i will only be using one FSR at a time depending which gear i am changing.

any help will be appreciated.


Hi @Andrew41527, sounds like a pretty neat project.

Almost certainly you’re going to have to condition the output of your shift circuit - the force sensitive resistors will output a slowly-varying (relatively speaking) signal that you want to turn into a hard edge. Perhaps familiarise yourself with how a schmitt-trigger works. The second image on that wiki article shows qualitatively how the analogue signal (U) is cleaned up into a digital signal (B) suitable for digital electronics.

In general, you can’t share signals in a voltage divider; I’d say you almost certainly need a separate one for each input.

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