[PD] pduino and FSRs

nick burge tectp at telefonica.net
Sun Apr 13 12:47:11 CEST 2008

Hello Martin, you are absolutely spot on here. In fact I want the numbers to
go up as I apply pressure so I've swapped the fsr and 10k as you suggest and
all works perfectly. No need for the expensive voltage divider then and more
difficult to calibrate several of them equally when a 10k resistor does the
Thank you to everybody on pd list who have helped me sort this out. 

FSR have a very _high_ resistance with no force. The resistance goes down
when you apply pressure. The circuit needs to look like this:

+------analog in

This will give a number that goes down as force is applied. If you want the
number to increase, switch the 10k and FSR.

Looking at the (considerably more expensive than a 10k resistor) phidget
voltage divider I see that the resistance is a multi-turn 1Meg
potentiometer. If it is set to zero ohms then pressing a sensor will short
out the power supply.
Also by convention the red wire is 5V, the black wire is ground and the
white is the analog signal.


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