Fluorescent starter-switch question

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On Sat, 07 Jan 2012 21:18:16 -0600, The Daring Dufas

Not exactly how they work, guys.
The glow tube, in series with the filaments and the ballast incorporates a normally open switch in parallel with the glow tube. .When power is applied, a glow discharge takes place heating the bimetal contact. A second or so later, the contacts close - which causes the current - limited by the ballast - to flow through the filaments - heating them up, emitting electrons so the flourescent tube can fire. The contacts short out the starter glow tube, so it shuts down, allowing the switch to cool and open. When the contacts open. the inductive kick generated at the instant of opening triggers the main discharge in the fluorescent tube. . When the main tube fires, the voltage across the tube is below the firing voltage of the neon starter glow-tube so it does not glow, and the filaments stay un-lit. If the tube extinguishes, or fails to light, the voltage across the tube increases to the firing voltage of the neon tube, and the starter attempts to re-fire the tube, repeating the sequence.
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On 1/7/2012 10:45 PM, snipped-for-privacy@snyder.on.ca wrote:

Darn, You're right, I forgot all about the inductive kick! D'oh! o_O
TDD
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WRONG
take apart a starter and look at it with no power applied.........OPEN CIRCUIT.......when energized the GLOW heats the bi-metal strip which CLOSES this completes the circuit lighting the ends of the lamp. once this happens the glow in the starter is extinguished...hence NO HEAT to keep the bi-metal strip in the closed posisition (completing the loop) bi-metal strip returns to the OPEN posisition the voltage spike ignites the fluorescent lamp with the voltage drop across the lamp keeping the glow of the starter from reigniting.......or if the fluor doesn't start the glow switch (starter) repeats the cycle.
DO YOUR OWN RESEARCH AS THERE IS A LOT OF WRONG ADVISE BEING GIVEN HERE,
I have been doing lighting for 35+ years and an electrical engineer for 25 of them. If you don't know what your talking about DON'T PRETEND YOU DO.
Herb Harrison Harrison Lighting & Neon est. 1979 ( yes, I am an expert in this one area.)
ps...the following was taken fronm fix-ya
According to Sam's F-Lamp FAQ:
The most common fluorescent starter is called a "glow tube starter" (or just starter) and contains a small gas (neon, etc.) filled tube and an optional radio frequency interference (RFI) suppression capacitor in a cylindrical aluminum can with a 2 pin base. While all starters are physically interchangeable, the wattage rating of the starter should be matched to the wattage rating of the fluorescent tubes for reliable operation and long life. The glow tube incorporates a switch which is normally open. When power is applied, a glow discharge takes place which heats a bimetal contact. A second or so later, the contacts close and provide current to the fluorescent filaments. Since the glow is extinguished, there is no longer any heating of the bimetal and the contacts open. The inductive kick generated at the instant of opening triggers the main discharge in the fluorescent tube. If the contacts open at a bad time, there isn't enough inductive kick and the process repeats.

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On 1/8/2012 10:20 AM, Harrison Lighting and Neon wrote:

You're right, I got it bassacwards. o_O
TDD
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<I haven't got the heart to snip the above excellent information>
I /think/ I get it now: That inductive kick is everything.
The system seems to work similarly to an automotive ignition coil, except that with the auto coil you have a transistor (or old-style breaker points) breaking current to the coil, and that break inducing a high-voltage spike.
In the case of the car engine, the spike jumps the gap across the spark plugs, whereas in the light fixture the surge causes a "spark" (ionized gases) from filament to filament inside the bulb.
Can you please explain why the spike would ignite the bulb instead of just creating a new spark across the terminals of the starter? Is it simply because the bulb is closer to the power source than the starter contacts?
--
Tegger

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wrote:

No - it is because the ionization voltage of the mercury vapour in the fluorescent tube is lower than the firing voltage of the neon tube - because of the "thermionic emissions" produced by the heated filaments. The fluorescent tube is a very low resistance - which drops to a virtual short circuit when it fires. Not sure what the voltage drop is across a lit tube - but it is LOW. - in the 30 volt range, I think - while a neon tube requires 70+
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Hi there:
this is a grey area of my knowledge, but my understanding is the ignition point (strike voltage) is lower in the lamp different vapor pressure (argon) and added Mercury make for a strike point around 160volts the vapor pressure in the starter is much higher but the spacing of the points is closer and no merc..........it will glow at around 90volts power takes path of least resistance the fluor is first in line of what is "effectively" a parallel circuit between the lamp and starter when it points are open during the strikeing of the lamp.
Hopefully that made some since to you as it would have been much easier if I could have posted a drawing. If your really interested I can look up the explanation in layman's terms and get it to you off group. Unfortunately its late and my brain is mush right now. my email is snipped-for-privacy@THISroadrunner.com

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But if the tube hasn't "struck" yet, then wouldn't there be an absence of current-flow through it until it strikes from the HT surge? Or does curent begin to flow during the ionization period?

I guess because the tube offers a path of less resistance than the now-open starter?

I'll bet. Like a lot of seemingly-simple technology.
The system seems to be basically two incandescent bulbs in the same housing with their light being produced by the gases between their filaments instead of from the filaments themselves. This seems to be the reason why fluorescents consume less electricity than incandescents: it takes much less current to keep gases glowing than to keep filaments glowing.
--
Tegger

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wrote:

If the tube doesn't strike, the starter sequence repeats itself. That's why some old lamps blinked on startup.
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no it does not matter, sorry about the 3 postings earlier, my computer went bonkers
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I just had a 20 inch (or so) light fixture go bad. I'd gotten it free, taking apart some equipment in about 1995, and used it for many years to light the hall of my trailer. Went to Walmart, and bought something similar for under ten bucks. Unless this is really essential to get the same light going again, I'd give a serious look at replacement.
Of course, you know your situation better than I.
Christopher A. Young Learn more about Jesus www.lds.org .
I have an older 18" fluorescent lamp that takes a 15WT8 bulb. As of this morning, it no marcha. I suspect the starter switch, which is your glass- tube type and is pretty black inside.
The problem is, I can't find any 15W starter switches at any location close to me. I can, however, cheaply and easily find a white, cylindrical starter switch that says, "13w, 30w, 40w" on it.
Can I use this "13w, 30w, 40w" switch with my 15w lamp?
--
Tegger



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I did visit Home Depot and another hardware store, but what I found there was not what I wanted. I did not think of Walmart, though. Will try that today. And I will pick up that starter anyway; for $4, it's worth a shot.
--
Tegger

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On Sat, 7 Jan 2012 08:21:34 -0500, "Stormin Mormon"

For under counter lighting I'd never go to flourescent any more with LEDs being at the state of development they have now reached.
As for desk lamps, likely the same - but the OLD desk flourescents I've had around - up to 45 years old now - did not use a starter - they used a "start button". You just hold the button down 'till it glows and flickers, then release and the light is on.
Other tha special purpose lights (like aquarium lighting) I thought virtually everything flourescent of recent design and manufacture used rapid start ballasts.. I guess that may still be true - but the specialty stuff, although of recent manufacture, is still of early design. Why change what isn't broken?
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I'm glad you suggested that, since I didn't think of it.
I did just what you suggested, and...nothing. No spark, no light. I then checked across the terminals of the starter and found roughly 2.5VDC. This drops to 0 if I turn off the on/off switch.
Then, since I'm considering the fixture to be junk anyway, I just cut off the starter and checked between the open ends of the wires. Same 2.5VDC. Held the wire-ends in contact, and nothing.
I'm finding continuity everywhere you'd logically expect to find it, and I tried three different bulbs, two brand-new.
I can't see that 2.5VDC is correct. The problem then must be the ballast, and not the starter?
--
Tegger

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On 1/7/2012 1:50 PM, Tegger wrote:

You should be measuring AC not DC.
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Sorry, I was measuring VAC. The "VDC" was a typo. I work on cars much more than I work with line voltage, so I'm too used to thinking "VDC" when I type.
--
Tegger

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I tried three tubes, two brand-new. Plus I tested the tubes' filaments for continuity.
I also tested for continuity within the fixture where it seemed logical to see it. I assumed I'd find an open through the ballast, which I did find.
But I guessed that when the ballast was fed with (a measured) 123VAC, I'd see something similar across the wires where the starter was, but all I found was 2.5VAC. That appears to be not enough to strike a spark, and no spark was had, no matter how slowly I brought the wires together.
In any case, I went to Walmart and bought a near dead-ringer of my old GE unit for a whopping $13. So this matter is done. Thanks to all who helped.
--
Tegger

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wrote:> Unless you can get a second hand one, not worth replacing.
It's in the trash now.

This new one does fire up immediately, whereas the old one took a second to start. That's a nice little upgrade for me.
--
Tegger

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Yeah thats a good way to check and see if the starter is really bad. I used to work in the amusements business as a tech. I took care of hundreds of flourescent lamps.I had a test starter that was just the case with the inards removed and a push button connected across the terminals. Still could be a bad bulb or ballast or both, starter too.
Jimmie
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On 1/7/2012 9:40 PM, JIMMIE wrote:

I seem to recall some fluorescent starters having a little red reset button coming out of the top.
TDD
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