Every Christmas I go visit Mom back East. The air is bone dry and the static electricity is un-freakin-believable. Every time I step out of the car I fry myself when I close the door. The spark is HUGE. In broad daylight, it's about the size of a dime. I scream and say bad words that one should not say in front of their mother.

Grabbing the door frame and then stepping down helps only sometimes. Other times, the charge is so big I get fried anyway.

All of the anti-static items I've seen are stationary mats and wrist straps and things. I'm going to make my own personal portable ant-static doohicky so I won't get zapped and consequently my mother will continue to believe I'm the fine upstanding young man she raised.

Your suggestions are welcome and encouraged.

Yeah, around here the static is annoying. I always hold onto my key and ground it on the metal of the door when I get out, that way the key gets the blast.

It must have plastic between you and the key because I tried that once with a bare key and the increased conductivity made it 3x as bad.

I built them years ago, I called it a Personal Discharge Device…

Just take a 1 Meg ohm, 1-watt resistor (just so it’s big enough) and bend a full loop on one lead and solder it closed. Then fold the other lead back on itself, solder it, and put it on your keyring.

Now just touch the resistor to anything before you do.

Matt-

Thanks! I'm going to make some BPDDs for the whole family and give them as stocking stuffers.

Barrett Personal Discharge Device

I am famous for my own kind of discharge device. It has a bad reputation tho....

I think I would be cautious about doing this with a car key. If this is a new car with a chip in the key you might be there for a while.

Can I ask what material your pants are made out of and what your car seat is made from?

Is this cotton to leather or polyester to vinyl?

Matt,
Can you share some of the theory behind the Barrett Personal Discharge Device?

Where do those pesky electrons go? The completed circuit is still through you, isn't it?

They used to sell a little strip of conducting rubber that trailed from the car's rear bumper to just touch the road. This was supposed to discharge static from the vehicle. Did it work? I dunno, I was only ten at the time, but they looked like a good flashy product for taking money off mugs!

Man-made fibre is the problem. Try cotton, wool or /mix socks, shorts and pants. You can actually buy conducting shoes, [not recommended for electricians though!], or try leather soles. Natural products like wool, cotton, linen etc., conduct well because they contain water mechanically locked into the fibers. They feel nicer to wear too, IMO, although leather soles wear out fast. My dad used to hammer iron studs into the soles and heels of his work boots to prolong their life, anyone remember them?

The idea is for both the vehicle and you to be at the same potential as the street.

Alan

I got my worst shocks like this wearing a suit while driving my '97 E350 with vinyl seats and the pants were some synthetic fiber. after pulling the plastic handle, pushing the plastic interior door panel and sliding across the seat out the door, intial contact with the metal body discharged a screamer.

But day-to-day routine in cotton jeans, no shocks.

If I understand his device, the idea is that the circuit is completed, but through a 1 meg resistance. There is still a discharge, but it is lower current for a longer duration, and the energy is dissipated heating up the resistor rather than heating up air or skin.

-Jon

Any way to put a capacitor and an LED in series to power the light for a few seconds. It would be a wildly inaccurate gauge of how many volts came across.

Anyone an electronics wiz?

This fits the category of personnel grounding, but I don't know if it will help stop the shock from vehicles.
http://www.desco.com/ViewProduct.aspx?pid=07560&h=1061

We use these heel grounders when working with electronics. They are not a substitute for wrist straps, but when you need to move around while working they give you the mobility you need.

In the 1980's,
the Negative-Ion Generator was a pretty popular sort of device that reduced static in rooms.
Not sure if you can still get them these days.
They even had small units that would plug into the cigarette lighter socket in your car.

Haligan,
for a little flash of light, try a small neon lamp. Attach a piece of wire to each pin, and hold it on one wire while touching the other to the metal when leaving the car.

An LED will not survive if the polarity is wrong, the diode will blow from the kilovolts. It might work in the forward direction, though (never tried it...)

My favorite place for getting shocked is the checkout at the supermarket. Whenever it's cold enough for the air to be really dry, the conveyor belt produces a lot of static electricity. The metal enclosure of the belt will then deliver a fat spark every time I go shopping there.

Star Trek,
I can't see how you equate static electricity with the constant current required to drive an LED.
Sure any LED (Light Emitting Diode) requires at least 20mA of constant current to make it light.
Of course that would depend upon the colour and the size of the LED..
Static electricity has no current.
It does however have a rather high voltage.
An LED uses between 1.2 and 2V, again depending upon size.
It is after all a diode.
Most LED's run on a DC supply require a dropping resistor in series to limit the current through the LED.
Have I got this all wrong?.

20ma will light an led. Doubt you'd get anywhere near that level of current from a 'static' discharge in the 'normal' environment, but there will be a current, if vanishingly small. I don't think the 'volts' is an issue here.

You could build a little device with a transistor and a battery to light up an led using 'static' as the switching voltage.
Sad, isn't it?

Alan

Yep. It's little projects like these that explain why I haven't finished landscaping the yard, or fixing that squeaky door, or re-caulking the bathtub. The list goes on...

"static" electricity implies charge on insulating surfaces or insulated bodies. When static electricity is discharged, the must be a flow of charge or _current_.

A human is very approximately one terminal of a 100pF capacitor, with the other terminal ground. On a dry day it is possible to charge this capacitor to 50kV. Discharge this in 1mS, and you have significant current, with perhaps 0.1 watt-second delivered.

I think that a neon lamp would be better as an indicator than an LED. An LED will light with uA of current, even though they are generally rated at 20mA. The neon will do a better job of tolerating all of the high current spikes from the capacitor discharge, and since it operates at higher voltage will probably give off more light for the same amount of current.

-Jon

OK, I'm a little upset that somebody isn't flying Mom to California for Christmas but I'll try to help anyway. The object here shouldn't be to measure the spark or turn on any pretty lights. Why not drive a Sonalert to keep Mom from hearing your naughty words??? We don't need no stinkin' sparks. And why think about various spark gaps when the goal is to prevent the buildup in the first place. First, get the ol' laundry sprayer out and go crazy spraying down the matts and all the fabric that your keester isn't on. Next, rig up a gator clip, wire, resistor assembly that you can leave clipped to your belt buckle while you're driving. Attach the other end to body metal. This will help abate PKSSS (Polyester Keester Slide Static Shock). The static straps that Alan mentioned will help dissipate any buildup between earth and the body/frame but won't help with potential between you and the frame. You can keep a well watered potted plant in the back seat and one of those Peltier Effect mugs full of water plugged into the lighter socket. Lastly, take two of those big dogs with the heads that bob up and down, fill them with water, and stick them on the rear deck.
Are you ready to buy Mom that plane ticket yet?
Joe