NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/sci/electron/22358

Internet Message Format | 1993-01-10 | 1.8 KB

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From: [e-mail] (Randy Casciola)
Newsgroups: sci.electronics
Subject: Those Anti-Static Mats
Message-ID: <[e-mail]>
Date: 11 Jan 93 00:25:16 GMT
Article-I.D.: cs.C0nyI5.MG2.2
Sender: [e-mail] (Randy Casciola)
Organization: CMU Vision and Autonomous Systems
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I just bought one of those cheap anti-static mats at a computer
store, one of the ones designed for you to place your computer
equipment on so that you can touch it to dissipate any static
before you touch your equipment.  I don't want to use this for
my computer, but for electronics work.  I wanted to test it
somehow, and the only way I could think of was with an DVM.  I
assumed that it would be somewhat conductive.  Well, when I held
the leads against the mat and pressed firmly at a distance of
about 1 cm, the resistance was greater than the highest range on
the DVM ( >20M ohms).  And the resistance from one end of the
ground cord to the other was about 1M ohm.  I assume they have
a 1M ohm resistor in series somewhere.  But my question is, if
the resistance of the mat is so high, how can it dissipate the
static?  I can buy the fact of it dissipating through 1M ohm or
so, but this mat seems like an insulator.  I measured the
resistance of another more expensive mat (the type designed to
be placed on the floor for you to walk on) and at 25 cm of
distance between the leads I measured about 20k ohms.  This
seems more reasonable to me.  Did I get ripped off with mine?
Will mine still work?

Thanks,

Randy Casciola
Research Engineer
The Robotics Institute
Carnegie Mellon
Pittsburgh, Pa 15213
[e-mail]