Re: low voltage & bulb species

From: L B (
Date: Fri Jul 06 2001 - 09:33:13 MDT

--- "Michael M. Butler" <> wrote:
> There are two factors here. Simplifying slightly:
> 1) there is a thing called the "strike voltage"
> which must exist so that the mercury vapor inside
> the tube will turn
> into plasma. If the strike voltage isn't present, at
> least briefly, the lamp will not light properly. The
> voltage
> required to maintain the plasma is lower than the
> strike voltage, so once on, the lamp might stay on
> through some
> voltage dips. I don't know the innards of your light
> bulb, but I am guessing they have an "electronic
> ballast"--that
> circuit might be able to handle a slight
> undervoltage as long as it's a relatively clean
> near-sinusoid. This brings us
> to:
> 2) ordinary incandescent-compatible light dimmers
> are a no-no for fluorescents because they do not
> produce the
> aforementioned RCNS. Instead, they typically use a
> thyristor (triac or quadrac) which is triggered
> periodically to
> conduct current at some point in the applied
> external ("mains") sinusoid. So the waveform they
> produce looks like a sine
> wave with part "chopped off"--in the extreme case of
> nearly-off, only a tiny part of the wave gets
> through, looking like
> a series of tiny sawtooths separated by zero volts.
> As one increases the dimmer dial setting toward
> "bright", an
> increasing part of the wave gets through. Problem:
> there is an abrupt rise in voltage every half-cycle.
> Fluorescents and
> their driver circuitry tend to not like that

Out here in Colorado the air is very dry and a person
can get full of static in a very short time. In the
winter, I have a favorite lamp. It is an old shop-type
lamp with a fluorescent bulb. As soon as I get within
a few feet of it the bulb starts to glow and I have
turned it on by touching it a couple of times. Yes, it
hurt. But I guess your answer above surprises me in
light of this (no pun). I don't really know much about
E, and can't reconcile the above with my own

Or maybe what happened to me explains what you said above.

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