Go Down

Topic: Can't decide whether the resistance is too high or too low to be measured (Read 863 times) previous topic - next topic

amundsen

Hello,

I am trying to build pressure sensors with Linqstat film but I don't know how to interpret the resistance's values I am reading on my digital multimeter.

Whatever the range I choose (up to 20 Mohms) the displayed value is 1. Does it mean the resistance is always bigger than the highest range or that it is always smaller ? I am sure the multimeter is OK because I have checked it with a resistor before.

JoeO


Hello,

I am trying to build pressure sensors with Linqstat film but I don't know how to interpret the resistance's values I am reading on my digital multimeter.

Whatever the range I choose (up to 20 Mohms) the displayed value is 1. Does it mean the resistance is always bigger than the highest range or that it is always smaller ? I am sure the multimeter is OK because I have checked it with a resistor before.

Yes, or your DVM/leads are bad. 
When you short the 2 leads together do you get a very small reading, less than an ohm?

winner10920

A way to check if its too low is to put the meter on continuity test, it will beep or eatever if its low ohms,
It sounds suspicious that it has the same value throughout the ranges, maybe the pressure switch is nott making a connection somewhere

amundsen



When you short the 2 leads together do you get a very small reading, less than an ohm?


Indeed. So do you think that if I read 1. it means the resistance is overriding the multimeter's range ?

winner10920

either its a really cheap multimeter and i would suggest getting a new one, or its not connected
the multimeters ive used would atleast give me like a .2 or some decimal number for a low resistance

Grumpy_Mike

Quote
So do you think that if I read 1. it means the resistance is overriding the multimeter's range ?

My very cheap meter gives this reading on resistance when there is no connection between the two probes.
I would say this was the reason rather than the resistance you were trying to measure was too high.

amundsen

OK, I found a very simple way to check : I first measured a 1M resistor with the multimeter set to the 200k range. The figure displayed was 1. Then I switched to the 2M range and it moved constantly between 1.011 and 1.012. Also when there's no connection between the probes it displays 1. too (infinite resistance). So 1. means much resistance. Well I could have figured out that sooner. That's what is happening when one works too much. Duh.

It means my homemade FSR are not very good !

Hondo_11

I know it's been a while since last posting about developing your on FSR's, but how goes your luck using Linqstat?  As I mentioned before, Linqstat does not give comparable readings like that of Velostat.  It does however give decent readings when read from the same side (whether that be 4-mil or 8-mil).  I've made several FSR's using Linqstat by placing a grid like array of equidistant cathode/anode's along the measurable surface of Linqstat.  You have to play around with the distances between your cathodes and anodes to adjust for sensitivity.  Cheers.

amundsen

Hello,

I have stopped working with Linqstat completely. I have gone another path, using Hall effect sensors on edges of my surface to track changing distance when pressure is applied on a plate. I'd give Velostat a try when I have more time.

Go Up