Connecting velostat conductive sheet to ArduinoUNO

Other Hardware General Electronics
1

Hi,
I am using a velostat conductive sheet, scotch tape and a conductive thread to make a pressure sensor out of that. Is there anyone who's already experimented on this.
Thanks in advance
Hema C Vadlamudi

2

The velostat is a variable resistor so connecting it to A0 will not be detected as there is no voltage to read.

You need to form a voltage divider with a resistor to 5v. Try 1k to10k for a start, depending on the resistance of the velostat.

Weedpharma

3

Its working. Thanks a lot.

4

Hi Team,
I am trying to do some experiments with conductive sheet (velostat). When I apply a force on the sheet it should change the value of resistance(output). I taking the output of the sheet by connecting to analog input Ao of Arduino. But I am not getting constant readings from arduino, even if no pressure is applied. Do I need to build any extra circuitry to stabilize the output value? Can anyone please tell how to stabilize the output value of Arduino?

Thanks in advance

Regards
VHC

5

What is the range of the variations? You may need to average out the variation by reading 5 times then take the average.

Weedpharma

6

It keeps on increasing the values. Sample output looks like this..
456
456
456
457
457
457
458
458
458.....
It is giving like this...

7

Time to provide the code.

Weedpharma

8

The code looks ok in that I cannot see why it varies.

Measure the R of the velostat while disconnected. See if it varies over time.

Put a fixed R of similar value in place in the Arduino. If no change in read out, it is a problem with R of the velostat changing.

Weedpharma

9

I checked the output of velostat using multimeter, I am getting constant reading. When the same is connected to arduino the output is varying. I am using is 10K resistor.

10

Do you have a pulldown connected to the analog pin?

11

The drawing shows one.........

Weedpharma

12

That stuff is conductive plastic meant for ESD protective packaging. It isn't designed to be a pressure sensitive resistor.

You are simply asking too much of it. It is going to vary with time and temperature, merely because the contact pressure and area will change as the metal and the plastic itself change size with temperature. The pressure will deform the plastic over time, causing more drift.

You can't expect it to be that stable. If you really need a pressure measurement that stable, you need something like a strain gauge.