FSR Velostat pressure sensor circuit with LM324 opamp

Other Hardware Sensors
1

Hello, I would like to share with you this circuit that can interface a FSR (Velostat) pressure sensor sheet with an Arduino.
Sandwitch a Velostat sheet between a conductive metal tape that is connected to 5volts and another conductive metal tape that will be connected to pin # 1 and 2 of an opamp (like LM324). You'll get a nice 0-3.7volts DC voltage depending on the pressure you'll apply, if you use a rail-to-rail opamp you'll get 0-5volts. The 20K pot adjusts the DC offset and sensibility. Good luck!

FSR Velostat LM324 intefacing.jpg
FSR Velostat LM324 intefacing.jpg960×720 133 KB

2

Something looks odd... Looks like the left OpAmp is wired as a voltage follower (negative input, pin 2, connected to output, pin 1) and the input, pin 3, is grounded. I would have expected the signal to be connected to the input of the amplifier and the output of the amplifier going to the next stage. I guess I don't understand how the circuit works.

3

Indeed there's a virtual ground at one end of the sensor so it'll ignore it rather efficiently!

4

Sir whats the correct configuration in order to interface an FSR to an FPGA board using LM324 with a 100k pot.. Need help..

5

Hi sir,

I am trying to use velostat sheet as pressure sensor. I am connecting the output of velostat sheet to analog pin of Arduino UNO. The values are fluctuating. How to get a constant output ?

Thanks in advance

6

You need to start your own thread, not post on a 4 year old thread that is unrelated to your question.