# Can I run two force sensitive resistors on three wires?

Image on the left is the provided sample wiring, image on the right is my proposed design.

I need to run two pairs of these FSRs ideally with 3 wires each as pictured, but I have almost no experience with resistors, and even less with feedback loop resistors.
Will my proposed design work to give independent readouts from each FSR without affecting each other?

Bonus question: Can I replace the resistor feedback loops with a potentiometer?
Bonus bonus question: If potentiometer is possible, is there a way to wire it so one single potentiometer can be used in the feedback loops of all four resistors in a 2x2 setup?

Example used for original image: Using an FSR | Force Sensitive Resistor (FSR) | Adafruit Learning System

Thank you!

Will my proposed design work to give independent readouts from each FSR without affecting each other?

Yes

You can replace a resistor with a potentiometer -- they are just resistors with a variable tap. Connect one end and the middle post and adjust the knob to the desired resistance.

I don't understand the last question. "Feedback loop" is not the correct term to use with this circuit.

jremington:

Will my proposed design work to give independent readouts from each FSR without affecting each other?

Yes

You can replace a resistor with a potentiometer -- they are just resistors with a variable tap. Connect one end and the middle post and adjust the knob to the desired resistance.

I don't understand the last question. "Feedback loop" is not the correct term to use with this circuit.

Thank you for the response!

For the last question, I was under the impression that the circled area below was referred to a resistor feedback loop, I think the correct term might just be "Feedback resistor"

In an ideal world, I would have one potentiometer that could adjust the resistance in that section on all four FSR, allowing for the sensors to be set to max out at a value between 100lb and up to 1000lbs.

From the spec sheet:

"In order to measure forces above 100 lb
(up to 1000 lb), apply a lower drive
voltage (-0.5 V, -0.10 V, etc.) and reduce the
resistance of the feedback resistor (1k? min.)
Conversely, the sensitivity can be increased for
measurement of lower forces by increasing the
drive voltage or resistance of the feedback resistor."

What does any of this have to do with your first post?

jremington:
What does any of this have to do with your first post?

The wiring schematic in my reply is the same as the left photo in the original post, where Rf is the resistor pictured in the first post between the ground and output from the FSR.

I’m wondering if I can use a single potentiometer in the place of the two resistors on the right portion of the original post (or in theory all four in an extended design) without affecting the readings of either FSR when used independently or at the same time, or if I would have to have two potentiometers.

EDIT: I see the confusion. When I looked at their provided wiring schematic, I didn’t realize that there is an op-amp involved in the picture. I’ve since found another post here that gave me some more information toward what I am trying to do, so between your help and that I’m good to go; thanks!