[solved] Help with anti static mat and power supply. - Page 1
Forum section: electronics / beginners

author: solder_boy132
author_rank: Contributor
timestamp: December 26, 2020, 06:54:49 pm
content: So setting up my newbie lab, I watched videos on anti static mats. I have been posting a lot of questions on the forum. Because im new, kind of. So anyways. In some videos they mentioned, that the cable to ground on the mat has a resistor to protect people from getting electrocuted by limiting the current, right? So i bought a large anti static mat, and i would put mt bench power supply there. But then i realized that, my power supply has exposed ground ends on the bottom. So if I place my power supply on the mat, would there be a direct path to ground?

author: msat
author_rank: Regular Contributor
timestamp: December 26, 2020, 07:54:12 pm
content: If the PSU doesn't have rubber feet, then presumably yes. But I suspect your mat has fairly high resistance per square.

author: MarkF
author_rank: Super Contributor
timestamp: December 26, 2020, 08:34:22 pm
content: Here is a typical static mat setup:The grounding cable from earth ground to the grounding block thatsnaps onto the matDOES NOThave a resistor.The mat will have a very high resistance (on the order of 10 MΩ).Try to measure the resistance with a meter. Measure both sides.The wrist strap plugs into the grounding block on the mat andDOEShave a resistor to prevent electrocution.There should beNOproblem setting any test equipment orPCBs being tested directly onto the mat.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 26, 2020, 08:43:39 pm
content: On top side (the blue side in the above pics) the mat is a very good isolator.Only on the black back side the mat is slightly conductive/dissipative.Other said, it doesn't mater if your power source or other wires stays on the colored surface.You still need to ground the mat with a resistor in series, as the instruction says.

author: MarkF
author_rank: Super Contributor
timestamp: December 26, 2020, 08:50:07 pm
content: https://youtu.be/NNXo4AbaKFc?t=205

author: RoGeorge
author_rank: Super Contributor
timestamp: December 26, 2020, 09:52:50 pm
content: Now I noticed the above picture says no resistor for the wire from mat to ground. This is wrong.USE RESISTORS on both wires. Both the mat to Earth grounding and the mat to wrist MUST have each its own resistor.Connecting the mat to the Earth (grounding the mat) without a resistor is a very bad idea.

author: CaptDon
author_rank: Super Contributor
timestamp: December 26, 2020, 10:15:24 pm
content: Most of the mats are directly grounded and the wrist strap hasa resistor 1meg up to 2.2meg usually. The mat resistance isrelatively high across any area. Be aware the mat will INDEEDcause weird outcomes if you lay a circuit board on the mat whichhas high impedance circuits. It will affect many analog circuitsand will drive any 'open' gates on cmos and 74ACTXXX I.C.'s.completely insane turning them into self oscillators which canruin the chip from being in a linear mode. I had an old blackrubber anti-static mat that smelled like an old tire and its resistancewas in the kilo ohm range on any two points and inch or so apart.I had to get rid of it. I had the 120 mains on a circuit board againstthe matt and I wasn't sure what the horrible smell was until I sawthe matt making smoke under the circuit board!!!