Is my anti static mat damaged?

Thread Starter

Joe Stavitsky

Joined Apr 5, 2020
125
I have 5-10 yellowish spots on my anti static mat, about 1cm in diameter. Do I need to replace the mat? I don't gave access to those giant cylindrical "probes" that they're generally tested with.

Examples circled in red. I tried to do some color adjustment, but I couldn't get any improvement.
 

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crutschow

Joined Mar 14, 2008
34,709
I doubt that's a problem.
You can do a rough check by just using standard meter probes to test the resistance between various points on the mat to the ground pin.
It should be in the neighborhood of a megaohm to several tens of megaohms
If your meter doesn't measure that high a resistance, apply 10Vdc to the mat, measure the current through the mat, and calculate the resistance from that.
Just make sure the meter is in series with the mat and power supply or you will blow it internal fuse.
My free Harbor Freight meter measures to 0.1µA resolution, which is equivalent to 100 megaohm with 10V applied.

Unless there's a significant difference between the resistance of the spot and the rest of the mat, it should be okay.
 

Thread Starter

Joe Stavitsky

Joined Apr 5, 2020
125
I doubt that's a problem.
You can do a rough check by just using standard meter probes to test the resistance between various points on the mat to the ground pin.
It should be in the neighborhood of a megaohm to several tens of megaohms
If your meter doesn't measure that high a resistance, apply 10Vdc to the mat, measure the current through the mat, and calculate the resistance from that.
Just make sure the meter is in series with the mat and power supply or you will blow it internal fuse.
My free Harbor Freight meter measures to 0.1µA resolution, which is equivalent to 100 megaohm with 10V applied.

Unless there's a significant difference between the resistance of the spot and the rest of the mat, it should be okay.

What current should I set at PSU?

Thanks again

Joe
 

MrChips

Joined Oct 2, 2009
30,986
That is a wide open question.
You set the PSU current limit to be higher than what the load demands. 25-50% higher is fine.
For many breadboard electronics projects, 1A @5V is a typical setting.
Sorry, I did not realize that your question was with reference to testing your anti-static mat with a 10V source.
If the resistance to be measured is greater than 100kΩ then the load current would be less than 100μA.
Hence set it to 1mA if you can achieve that.

Or just put a 100kΩ resistor in series with your power supply. Then you can set the current limit to whatever you wish. The current drawn from the PSU set to a voltage limit of 10V will always be less than 100μA.
 
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