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Posted by clare on March 24, 2009, 4:18 pm
On Tue, 24 Mar 2009 09:14:39 +0000, Tim Jackson

 I have used an NE2 based circuit tester for decades. Stick one prod
in the live side of a plug and touch the other lead. It lights the
light and I've NEVER felt it.

Posted by vaughn on March 24, 2009, 4:58 pm

   Yep!  That is the best way to find (or verify) the "hot" wire.  Inside a
switch, or as part of a tester, an NE2 is usually wired in series with a 47K
resistor.  That limits current to something less than 2.5 mA.  ("less than"
because the bulb does not fire for the full cycle)


Posted by Tim Jackson on March 24, 2009, 7:25 pm
 vaughn wrote:

The neon testers we get here in the UK have at least 470k resistance so
pass under 1mA (which is generally considered the threshold for
sensation, although of course YMMV) at 230V and produce a dim glow that
wouldn't usefully illuminate anything, but is visible when looked at
directly.  I just tried 100k/230V with a CF lamp in darkened room and it
didn't flicker.  A simple experiment can be worth hours of theorising.

I've never seen a switch illuminated the way you describe, so I've never
checked, but I can't imagine them being permitted under the relevant
British or European standards.  Maybe in the US it's permitted.  But I
think it is irrelevant.

Perhaps the OP will tell us if he is using an illuminated, electronic or
dimmer switch, I do agree that if so, then the solution to the flicker
may be to try a conventional switch.  If not, he has a problem.


Posted by vaughn on March 24, 2009, 7:56 pm

   I posted based on decades-old memory, so 470k might well be correct.


Posted by Johnny B Good on March 24, 2009, 8:51 pm

 I seem to recall a 220K resistor being used (hopefully, a high voltage
type). Neon cold cathode lamps (the tiny neon 'bulb') have a striking
voltage of around 90 volts and stabilise at about 60 volts for the glow

Regards, John.

 Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.

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