From: email@example.com (Eric Y. Chang)
Subject: Re: fluorescent lamp inverter problem
Date: Sat, 4 Jan 2003 21:21:38 +0000 (UTC)
Organization: California Institute of Technology, Pasadena
NNTP-Posting-Date: Sat, 4 Jan 2003 21:21:38 +0000 (UTC)
X-Newsreader: TIN [version 1.2 PL2]
Da Man (firstname.lastname@example.org) wrote:
: A few things bother me with the tube you have: 1) It's quite odd to have a
: florecent tube with only 1 wire per electrode, 2) no heater, 3) Most newer
: electronic ballasts don't have replaceable tubes(a real 10,000 hours later,
: the plastic, the electronics (HV breakdown), and the caps won't be in the
: greatest shape + the companys want you to buy a new one) 4) every 2 pin
: replacement tube I saw had a built in starter. Look for places between the
: pins and the tube where they could hide a small tube about 1/4" by 3/8".
: So to me it really looks like what is happining is that: you have circuity
: that ignites and drives the tube with a very differnt voltage waveform then
: what would be used for 120V (or 220V if your far away from here!) operation.
: So, turning it on, the tube ignites due to a high voltage produced from the
: current limited "driver". Since the voltage is higher then when driving it
: the standard way, the starter keeps ionizing, thus kicking in, effectively
: shorting out the electrodes (there may not be enough current to make them
: glow), and shutting the lamp down. When the starter cools enough to open,
: the contacts are so close together that the hot ionizing gas rapidly ionizes
: again, sucking all the avalible current from the highly current limited
: supply (no low frequency 60 Hz and no large inductor for a big kick), and
: not allowing the tube to ignite. The contacts in the starter would likely
: oscillate at a few times a second.
Hi Jeff. I looked around a little and found that you are exactly correct.
Everything you said is correct. This is what I get for leaving out the
Doing a quick google search revealed that what I erroneously called
"bi-pin" is actually 2-pin. "bi-pin" actually means 4 pins. The only
place it means 2-pin is on www.deja.com, where another clueless poster
joins me in incorrectly applying it to 2-pin tubes. Also, despite the
fact that I'm sure that I saw a camping lantern with a 2-pin tube, all
the docs said that the 2-pin compact fluorescent lamps (usually
Philips PL type) contain an integral starter and are only for use with
old-fashioned magnetic ballasts. The newer 4 pin (also called bi-pin)
lamps are for use with the electronic ballasts.
So your explanation is entirely correct. To test it out, I put a 0.01
uF 1kV ceramic disc capacitor in parallel with the blocking capacitor
in Sam Goldwasser's document. This is intended to get enough current
through to get that blasted bimetal strip out of the way. Indeed, it
worked just great, and the lamp turned on, and stayed on. Just great.
Nice and bright, and the transistors did not need heat sinking.
Next time, the correct thing to do would be to use thicker wire and
much less windings on the secondary, and add an inductor in order to
give the kick when the integral starter opens. Or, just make things
simpler and use a 4 pin lamp, wired with the filaments on heater
windings (the transformer will need one more pair of windings).
Sam and Don need to update their FAQ's, which are nonetheless useful,
although slightly incomplete in this matter.
Again, thanks for your help. The thick wire concern was not quite
correct, and my saturation guesses may have been a red herring.