Fluorescent starter-switch question

[Tony Miklos]

You should be measuring AC not DC.

[Tegger]

Tony Miklos wrote in news: [e-mail]:

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]

harry wrote in news: [e-mail]:

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]

Tony Miklos wrote in news: [e-mail]:

I have a similar desk-lamp unit. It dates from the early-'70s. It has two buttons: one to turn the unit ON, and one to turn it OFF. Both are momentary switches, and you need to hold down the ON button until the unit lights up.

[The Daring Dufas]

I lost mine in a move and really miss it. It was great for working on detailed things where I need a lot of light. ^_^

TDD

[Tegger]

harry wrote in news: [e-mail]:

I'm having a bit of trouble wrapping my head around this.

Do the ionized gases in the tube present less resistance to current-flow than the tiny air-gap formed as the starter contacts begin to re-open?

[The Daring Dufas]

The glass envelope of the starter is basically a neon lamp with a bi-metal short. When current first flows through the starter, the bi-metal strip heats up and pulls away from the other terminal and if current is flowing through a good florescent tube, there is enough current/voltage to light off the neon in the starter. The heat from the lit neon keeps the bi-metal strip hot enough to stay bent away from the other contact. When you hear a click, click, click along with the ends of a darkened florescent tube glowing on and off, it's usually because the tubes have worn out and no current is flowing through the lit tubes so the starter keeps heating up and cooling down as it tries to heat the filaments in the tube ends to ionize the gas in the tube and start the reaction that ionizes all the gas in the tube so it glows. The ionized gas is what conducts electricity to keep the neon gas in the starter lit. I hope this helps you understand how it works.

TDD

[JIMMIE]

[e-mail]:

LMAO

[JIMMIE]

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

[The Daring Dufas]

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

TDD

[clare]

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.

[The Daring Dufas]

Darn, You're right, I forgot all about the inductive kick! D'oh! o_O

TDD

[Harrison Lighting and Neon]

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.

[The Daring Dufas]

You're right, I got it bassacwards. o_O

TDD

[Tegger]

harry wrote in news: [e-mail]:

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]

"Harrison Lighting and Neon" wrote in news: [e-mail]:

[Tegger]

harry wrote in news: [e-mail]:

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.

[clare]

On Sun, 8 Jan 2012 23:29:04 +0000 (UTC), Tegger wrote:

>

[clare]

If the tube doesn't strike, the starter sequence repeats itself. That's why some old lamps blinked on startup.

[Harrison Lighting and Neon]

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 [e-mail]