Fluorescent bulb types...
Existential Angst
I have a basic understanding of how these tubes work (iirc, they operate off
the Franck-Hertz ionization), except for the single pin 8' jobbies, that you
don't have to twist to install -- really neat.
I thought tubes needed a filament at each end, to get the thing started?
Hard to have a filament with just one terminal, no?
Do these types compensate with a higher starting voltage, and thus don't
need filaments?
In bulbs with filaments, once the whole bulb is lit up, those filaments are
cold, right?
I have only seen single pin in 8' bulbs. Why is this?
Someone posted an inneresting link on all-that-is-fluorescent not too long
ago. I looked at that link, very nice, but I didn't see this topic.
--
EA
sta...@prolynx.com
wrote:
They don't have a filament because the ballast supplies a high-voltage
pulse to start the arc. They've historically only been used in
industrial settings where lighting was run off 208/240/440/480 and the
magnetic ballasts could be heavier duty and more expensive. Shorter
ones can do the same now with solid-state ballasts, the filaments are
still there to provide backwards compatibility for older fixtures.
You don't HAVE to have a filament to warm things up if you've got
enough voltage to start the arc. That method works even if the
filaments are busted.
On looking around, 6/30/2010 is the last date for manufacture of the
older magnetic ballasts in this country. One of those "green" things
that got passed without a lot of fanfare.
Stan
Jon Danniken
>
> On looking around, 6/30/2010 is the last date for manufacture of the
> older magnetic ballasts in this country. One of those "green" things
> that got passed without a lot of fanfare.
Thanks Stan, I wasn't aware of that. Doing a little digging, I found the
following from
(http://todaysfacilitymanager.com/facilityblog/2009/09/targeted-magnetic-ballast-phase-out-to-begin-next-year.html):
> Bloom pointed out that DOE exempted three types of T12 magnetic
> ballasts from the rule:
>
> T12 dimming ballasts that dim to 50% or less;
> two lamp F96T12HO ballasts designed for outdoor sign applications
> where temperatures may fall to as low as -20F, and;
>magnetic ballasts with power factors less than 0.90 designed and
>labeled for residential building applications.
Jon
Ned Simmons
The "filament" in a fluorescent lamp is usually referred to as a
cathode. The 8-foot single pin tubes have a tungsten cathode that's
the same as those in bi-pin lamps; it's just connected in a loop
rather than across the two pins. Once the lamp is lit, regardless of
whether the lamp has one or two pins, the cathode has the same
function -- it's the source of the discharge that excites the
phosphors on the lamp envelope. The cathode has a heavy central core
with a loose "basket" wound around it that enhances emission.
While looking for a picture of a cathode this patent caught my eye. I
designed and built the feeding mechanism and high speed cutter
described in the patent. I didn't realize 'til now the process had
been patented.
http://www.freepatentsonline.com/7462991.pdf
--
Ned Simmons
Lewis Hartswick
> In bulbs with filaments, once the whole bulb is lit up, those filaments are
> cold, right?
Well not quite, they are pretty hot due to ion bombardment.
...lew...
Existential Angst
news:c4b6n5pg62u5slurg...@4ax.com...
So the cathode is heated, right? Which means it needs TWO connection wires,
right?
Is that single pin somehow segmented/insulated for two conductors??
Once the lamp is lit, regardless of
> whether the lamp has one or two pins, the cathode has the same
> function -- it's the source of the discharge that excites the
> phosphors on the lamp envelope. The cathode has a heavy central core
> with a loose "basket" wound around it that enhances emission.
Does this mean that the cathode(s) *stay* heated, while the bulb is
operational? Or less heated upon steady-state? Or cold?
--
EA
Don Klipstein
>"Ned Simmons" <ne...@nedsim.com> wrote in message
>news:c4b6n5pg62u5slurg...@4ax.com...
<SNIP to here>
>> The "filament" in a fluorescent lamp is usually referred to as a
>> cathode. The 8-foot single pin tubes have a tungsten cathode that's
>> the same as those in bi-pin lamps; it's just connected in a loop
>> rather than across the two pins.
>
>So the cathode is heated, right? Which means it needs TWO connection wires,
>right?
>Is that single pin somehow segmented/insulated for two conductors??
The cathode is heated only by the arc. Fluorescents with only one pin
on each end can only work with a general class of ballasts that is called
"instant start" in North America.
>>Once the lamp is lit, regardless of
>> whether the lamp has one or two pins, the cathode has the same
>> function -- it's the source of the discharge that excites the
>> phosphors on the lamp envelope. The cathode has a heavy central core
>> with a loose "basket" wound around it that enhances emission.
>
>Does this mean that the cathode(s) *stay* heated, while the bulb is
>operational? Or less heated upon steady-state? Or cold?
In instant start lamps, the cathodes are only heated by the arc.
Fluorescent lamps in preheat fixtures, once they are started, have their
cathodes heated only by the arc.
- Don Klipstein (d...@misty.com)
larry
There are the lamps you mention, which always have a
filament at each end, whose heat sustains the ionization.
It may be preheated (voltage across the filaments) to help
start the ionization of the mercury vapor, or very high
voltage to start the ionization. Once operating, the
current thru the vapor and filaments keeps them heated. hot
metal makes a good electron emitter.
The other type of fluorescents are called "cold cathode" and
don't depend on filaments. They use an electrode at each end
and use a current limited high voltage supply, and a fine
tuned blend of rare gases at specific pressures. These are
long life and cool running, used in somewhat permanent
installs like cove lighting and advertising signs.
Don's webpage has info on lighting devices and technologies-
members.misty.com/don/f-lamp.html
-l
whit3rd
> The other type of fluorescents are called "cold cathode" ...
> These are long life
Well, relative to the service life of incandescent lamps (1000 hours
more or less) they have a long service life. The collection of
tricks for starting them, though, includes small amounts of
radioactive gas with a few years half-life. Twenty years from now,
an attic incandescent lamp will come on every time, your attic
CCFL won't.
Martin H. Eastburn
8' single/double - don't know yet - 20' in the air. Wish they were T16's.
The small, green ended very long life types.
Mine won't start well if cold. Today I got them lit mid-day for use at dusk.
Martin
Richard J Kinch
> older magnetic ballasts in this country. One of those "green" things
> that got passed without a lot of fanfare.
Oh, no. Another thing I have to hoard!
On the other hand, Diamond strike-anywhere matches seem to be back!
Stormin Mormon
ages. Found them in an old country store, and
bought more than one pack.
--
Christopher A. Young
Learn more about Jesus
www.lds.org
.
"Richard J Kinch" <ki...@truetex.com> wrote in
message
news:Xns9D1D1A99EF9...@216.196.97.131...
Doug Miller
>I remember couldn't find strike any wheres for
>ages. Found them in an old country store, and
>bought more than one pack.
>
the bottom where it belongs?
Don Klipstein
CCFL is not CFL - single C is "Compact", double C is "Cold Cathode".
Some units are both, usually with wattage in the 3 to 9 watt range, and
most 9-watt CFLs only qualify for one C. :)
In general, CFLs having integral electronic ballasts (including over
99.7% of spiral type units and over 99.8% of spiral type units with screw
bases allowing substitution for incandescents) appear to me to not have
added radioactive isotopes or notably harmful radioactive materials in
order to start. Electronic ballasts, "rapid start" ballasts, "trigger
start" ballasts and "instant start" ballasts *at least generally* negate
the need for "glow switch starters" which are the main usage of
radioactive materials for fluorescent lighting.
- Don Klipstein (d...@misty.com)