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Questions &/or issues related to products in the Flex / Force category should be posted in this forum. includes Force Sensitive Resistors, Load Cells & Amplifiers, Pressure Sensors, etc
#202549
Dear Sparkfun Team,
I have recently purchased the following multiplexer ... https://www.sparkfun.com/products/9056 and I would like to connect 16 Flexiforce sensors. I would like also to use a non-inverting op-amp in order to linearize the output and adjust the sensitivity.
Could you please advise me what would be the correct circuit to do?
Should I connect every sensor to an op-amp and then the output of each op-amp to the multiplexer, or I should connect each sensor directly to the multiplexer and then the analog output of the multiplexer to a single op-amp? In the first case I am using 16 op-amps, while in the second just one.
I am looking forward to hearing from you.
Best wishes,
George
#202602
Hello, and thanks for using our new forums!
I would like to connect 16 Flexiforce sensors. I would like also to use a non-inverting op-amp in order to linearize the output and adjust the sensitivity. Could you please advise me what would be the correct circuit to do?
Unfortunately I don't have a circuit for this.
Should I connect every sensor to an op-amp and then the output of each op-amp to the multiplexer, or I should connect each sensor directly to the multiplexer and then the analog output of the multiplexer to a single op-amp?
It's more work, but if you're trying to match all the sensors so that they react the same you're probably going to need to us 1 op-amp per sensor, then feed that output into one of the channels on the MUX. That way you can dial in exactly the output you're looking for for each sensor.

You might test them with only a single op-amp on the output side of the MUX first though. It's possible that they are close enough as is so that you don't need to do any adjustment at all, or can do the adjustment in code on whatever microcontroller you have the MUX connected too.
#202649
Hi Chris,
Thank you very much for your advice. I have already designed a pcb with 16 op-amps but I am trying to simplify the circuit in case as you said the sensors are close enough (although the bibliography indicates variability). One last question please. If I will use a single op-amp is there a possibility to experience any cross-talk? Best, George