On Tue, 08 Apr 2008 23:11:46 +0100, Pete Verdon
d wrote:

How are they supposed to work?

I tagged one of these onto the end of a TLC order just to get an ok
electrician's-sized screwdriver. I don't intend to use the alleged
"testing" facility, but I'm curious how it's supposed to work. It looks
like it's meant to be touched to a live terminal and have the current
flow up the shaft, through a capsule which I assume is the bulb, and
then go via a brass end-cap *into my hand*. The last part of that I'm
not particularly keen on.

I assume that, while they're not well-regarded by most here, neon
screwdrivers don't actually electrocute their owners during intended
use. Is it just that the current flow is very small, and almost all the
voltage is across the neon? Can anyone with a better grasp of electrical
theory explain?

Cheers,

Pete


The 'driver body contains a neon capsule in series with a large value
resitor.

When a live terminal is touched a voltage is applied across a series
circuit comprising the neon (a high resistance when not conducting),
the resistor , your body and the earth path.

At some point of the mains cycle the neon gas conducts causing a low
resitance path through it and the gas glows.

The current that flows is limited to a very low value by the series
resistance and the rest of the return path. This current is low but
sufficient to keep the neon conducting.

Unless there is fault with the 'driver there isn't any danger to the
user. I've never known of any problems caused by one going faulty.