Static electricity monitor for blind.

[Graham.]

That's basically the first project I built using a FET. A 2N3819 with a few cm of wire as a pickup probe of the gate and no biasing components

[Brian Gaff]

Hi does anyone produce a probe that can detect rising electrostatic charge, say on a person. I have a friend who you can hear crackle when they use my vacuum cleaner. I do not have this trouble, but it occurred to me the only way currently I know of is a gold leaf electroscope, though these days tending to use aluminium cited plastic, which move apart as you bring the electrode near a body which is charged up. What I was looking for was the static equivalent of a metal detector, where a rising tone can be heard as you bring the probe near a charged up item. Anyone seen such a thing? Not much good if it costs an arm and a leg though!

Brian

[whisky-dave]

Yes, I saw one of Friday, one of our research students is doing something with static and rotating magnetic fields or rather he is trying to. He came to me asking if I had a meter and I said no, we can only measure proper volts not those silly static ones. So he went away and brought a static voltage meter for about £140, which you connected to a standard DMM to give a reading, and appaently you can get a version which produces a tone dependent on the static voltage but that was more expensive. He spend a while trying to get the one he had bought working with our van der graaf generator but had little success as the probe seemed to need to be just a few inches from the dome, he got a reading on 0.4V which according to the manual you multiply by 1000. he switched the polarity switch on the unit then he got a voltage of 1.5V, why we couldn't work out why. Then 5pm came so I had to go home.

He'll be back, I'm sure and when he does I'll get some more info and report back. So in the meantime save up a few arms and legs ;-)

I'd look at his footware as that could be causing static build up, as I get a few shocks if I drag my feet across the floor sometimes.

[Harry Bloomfield]

whisky-dave laid this down on his screen :

It could be the vacuums friction on the carpet generating the charge and the footwear helping retain it.

[Andrew]

I used to get a dreadful static belt from my old Astra F estate, but only if I was wearing a fleece.

After driving about 5 miles in hot dry weather, and getting out as soon as I touched the drivers door to shut it, crack. Ouch.

Current Astra H doesn't seem to have this problem though.

Maybe your friend should try wearing different shoes to see if that makes any difference ?.

[T i m]

<snip>

I think that's you building up a charge as you get out (nylon rubbing across the seat) and then discharging it to the car? [1]

It can also be the car building up the charge (especially in hot / dry weather) and discharging though you to ground.

More carbon in the tyres?

I can often feel the charge on the outside of some vacuum cleaner hoses and why you shouldn't use them for cleaning PC's.

If I ever do, I hold the metal pickup tube so that at least that bit is at the same potential as the case (that I'm holding with the other hand).

I used to regularly get a belt off the Sierra Estate, when getting out of it and touching the door to close it, till I got one of those anti-static straps that I bolted underneath onto the towbar.

When moving above just a few MPH it would 'fly' and so didn't wear out. Once I stopped it would drop back down, touch the ground and then discharge the car before I did. ;-)

Cheers, T i m

[1] On similar lines, we fitted an electric fence (8kv) around daughters rabbit hutch and got a mutual friend to test it for us <weg>.

He could hold onto the wire if wearing his boots. He would jump if in his socks ... and would jump, yell and dance if in bare feet (or one bare foot even). ;-)

He wouldn't test it on his nose but both the dogs did, but only twice each.

Cheers, T i m

[Brian Gaff]

Being high impedance though does this not also pick up transformer buzz and any from that might be around the place? Brian

[Brian Gaff]

Its a she, and its not the feet. It seems to be her, but I'm not asking her to undress and try it again.

Brian

[Brian Gaff]

It does it if she vacuums the toilet cistern top just the same, indeed just holds it. I think that her clothing has to be part of it though, but her boss, both of whom I employ does not get this either. However sometimes I can charge stuff up easily, at other times not. The getting out of a car time is one of those when you touch the metal of the door. The spark then is quite loud, but in this ladies case its like a continuous sizzling sound. Very odd. Brian

[Andrew]

[Harry Bloomfield]

Brian Gaff wrote on 01/07/2019 :

Where is your sense of adventure :D

[polygonum_on_google]

I am sure this will be of no help to you, Brian, but...

Someone just two metres away used to suffer lots and lots of static jolts. Pretty much every time she touched the car door was a classic but there were lots of other circumstances.

When treated for hypothyroidism, this slowly, very, very slowly, improved. Now she just seems very slightly more sensitive than some.

Given that thyroid hormone is directly connected with energy management in biological cells, the reason is quite possibly identifiably given a bit of decent research.

It is quite widely known and understood by quite a number of other sufferers.