Hi all,
what is the typical resistance of an antistatic wristband? I don't see the point in spending quite a lot of money (the cheap ones seem either uncomfortable or to easily damaged... so you need to buy a tester to verify its working...
) if a 30 cent wire and a 5 cent resistor will do the same trick and can be made to fit exactly. From the minimal data I've found so far, it seems that 1MOhm might be a good value.
What kind of material will do for the working space? I would think a conducting, earthed plate would be good.
Cheers,
Hans.
what is the typical resistance of an antistatic wristband? I don't see the point in spending quite a lot of money (the cheap ones seem either uncomfortable or to easily damaged... so you need to buy a tester to verify its working...
) if a 30 cent wire and a 5 cent resistor will do the same trick and can be made to fit exactly. From the minimal data I've found so far, it seems that 1MOhm might be a good value.What kind of material will do for the working space? I would think a conducting, earthed plate would be good.
Cheers,
Hans.
The typical resistance of an antistatic wrist band is usually either 1 megaohm, 5 megaohms, or 10 megaohms.
Even with these high resistances, the strap can still discharge you pretty quickley if it is connected to earth ground. The wrist strap has a built in resistance to protect you in case the main hot wire of the outlet makes electrical contact with the earth ground wire (and thus your earth ground could be at 120VAC in the US, 240VAC in many other countries). If there is, say, a 1 megaohm resistance in series with your body when the hot wire contacts the earth ground wire, you may get a jolt, but you should probably be okay.
Using a conducting eartherd plate would be a great idea, but just like the wrist strap, make sure it is connected to earth ground THROUGH a series resistance just in case. The same value resistance can be used in series with your earth plate with good success (1, 5, or 10 megaohms).
Even with these high resistances, the strap can still discharge you pretty quickley if it is connected to earth ground. The wrist strap has a built in resistance to protect you in case the main hot wire of the outlet makes electrical contact with the earth ground wire (and thus your earth ground could be at 120VAC in the US, 240VAC in many other countries). If there is, say, a 1 megaohm resistance in series with your body when the hot wire contacts the earth ground wire, you may get a jolt, but you should probably be okay.
Using a conducting eartherd plate would be a great idea, but just like the wrist strap, make sure it is connected to earth ground THROUGH a series resistance just in case. The same value resistance can be used in series with your earth plate with good success (1, 5, or 10 megaohms).
Hi,
that cannot be the purpose of a wrist band!!
Surely the purpose Hans is enquiring about is to protect FET gates from static charge causing the gate to source voltage exceeding the device limits.
I would expect the wrist band to be connected to the bench/maintained equipment NOT to mains/safety earth.
that cannot be the purpose of a wrist band!!
Surely the purpose Hans is enquiring about is to protect FET gates from static charge causing the gate to source voltage exceeding the device limits.
I would expect the wrist band to be connected to the bench/maintained equipment NOT to mains/safety earth.
Thank you guys!
I guess a tiny fuse would be a good idea just in case some catastrophic failure should occur, even if the chances for an unlikely failure into ground being lethal are quite minute in this case ... it would be rather embarrassing to have a heart seizure while trying to save your fet's
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(Epitaph: 'Did the fet survive?')
I guess a tiny fuse would be a good idea just in case some catastrophic failure should occur, even if the chances for an unlikely failure into ground being lethal are quite minute in this case ... it would be rather embarrassing to have a heart seizure while trying to save your fet's
.
.
.
.
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(Epitaph: 'Did the fet survive?')
One usually connects the wristband to the bench cover, but the bench and/or cover should be connected to safety earth through a 10 meg resistor..........
Most antistatic tools/ bench plates etc. have R's in the rder of tens of megohms, which does the antistatic trick without imposing too much danger if a ground fault should occur.
A metal plate will absolutely do as a desk cover, although the expensive ones are usually a sort of plastic/vinyl mix.....
but if you are working with powered up stuff on a metal plate, it is easier to create "smoke signals"..
Most antistatic tools/ bench plates etc. have R's in the rder of tens of megohms, which does the antistatic trick without imposing too much danger if a ground fault should occur.
A metal plate will absolutely do as a desk cover, although the expensive ones are usually a sort of plastic/vinyl mix.....
but if you are working with powered up stuff on a metal plate, it is easier to create "smoke signals"..
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