Re: [APD] Re: Need guidance with DIY compact fluorescents

["S. Hieber" <shieber at yahoo_com>]

I believe the 13 watt bulbs are really just like the
"old-fashioned" bulbs that used the little "tin-can"
starter except that the starter element is built into the
base of the bulb.

Rapid Starts (pre-heats) require a rapid start ballast1,
which preheats the filaments with current before sending
the "starter" voltage into the bulb. And then the filaments
continue to have some current running through them, which
serves no useful purpose unless the place where the bulb is
used is particularly cold. Rapid starts generally will
light with an appropirate electronic ballast. Some
semi-electronic ballasts, pre-heat, then drop the current
through the filaments once the bulb is lit.

Scott H.
--- gbooth at frii_com wrote:

> In general, there are three styles of ballasts. "old
> fashioned" starter,
> rapid start and instant start. The AHS 13 watt bulbs are
> rapid start.
> 
> The old fashioned kind used the little silver starters to
> first heat the
> bulb filaments. The heated filaments allow the internal
> arc to be stuck
> with relatively lower voltages. Once the arc is struck,
> the starter opens
> the filament circuit (or limits the current flowin
> through them).
> 
> Rapid start are the typical magnetic ballasts and some
> electronic
> ballasts. They use simple internal circuitry to heat the
> filaments, strike
> an arc then limit the current that is supplied to the
> bulb.
> 
> With both these types, there is always current flowing in
> the filaments to
> keep them warm (why the ends are always very hot). This
> extra current uses
> extra power.
> 
> Instant start ballasts are designed to supply a higher
> voltage across the
> bulb. This allows the arc to fire without heating the
> filaments. In an
> instant start configuration, the pair of pins on each end
> of the bulb are
> actually shorted together! With no current flowing
> through the filaments,
> energy is saved.
> 
> I beleive this is what the newer 32-watt T-8 bulbs are
> set up for. Their
> pins are shorted together and therefore require an
> Instant Start
> electronic ballast. They output about the same amount of
> light as a NO 40w
> bulb without wasting the extra 8 watts that would keep
> the filaments warm.
> If you tried to run them with a normal ballast, you would
> short out the
> internals of the ballast.
> 
> I beleive that any bulb designed for starter or rapid
> start use can be
> driven with an instant start ballast rated for the bubs
> wattage. I have
> some linear 8 and 13 watt T-5 bulbs I use for under shelf
> lighting that
> use instant start ballasts. They run prerty cool.
> 
> George
> 
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=====
S. Hieber

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