28 May
2004
28 May
'04
9:01 a.m.
>>>> "Tony" == Tony Duell
<ard(a)p850ug1.demon.co.uk> writes:
Tony> Use a limiting resistor!
But not a 100 ohm one -- that might as well be a short. A megaohm is
probably better. Voltage rating may be an issue.
> In this process, be sure you keep your fingertips
WELL away from
> the metal shaft of the screwdriver. The most natural position for
> the
Tony> Considering the shaft is connected to ground through a very low
Tony> resistance in your set-up, what's the harm in touching it ?
That's true IF the wire hasn't popped loose, and IF the limiting
resistor has a much smaller resistance than your body.
> There are special "safety" screwdrivers
(designed/approved for
> work in live mains power systems). Those have shafts that are
> insulated right up to the tip.
Tony> And are often only rated to 1000V. That's enough for working on
Tony> live mains (which is where I use them), but CRT anodes run at
Tony> 10-25 times that voltage.
True.
> You could give yourself a little extra safety by
wrapping a few
> layers of electrician's tape around the top 2-3 inches of the
> screwdriver
Tony> I am not sure what the breakdown voltage of insulting tape is
Tony> (yes, I always call it that!), but it's not that high. I doubt
Tony> that a layer would stand 10kV (which is what you're asking for
Tony> here, at least on a colour CRT).
True again. So I guess "keep your fingers at the top of the handle"
is the better answer.
paul