Schematic: Turning on dead fluorescent light bulb. - Page 1
Forum section: electronics / general

author: ResR
author_rank: Regular Contributor
timestamp: September 07, 2013, 08:35:30 pm
content: Long time ago I found this schematic on some russian site (I think someone got awarded for inventing this in soviet union, if I remember correctly, drawn from my old schematic notebook) and thought to share it, because it is rare on the internet, with this you can turn on fluorescent tubes that is dead in normal light fixtures. For R1 I used 60W light bulb (not available in some countries) or a 40W fluorescent lamp ballast, any 30 - 60 ohm high power resistor is good also. The bulb is a little bit dimmer, but you can get some more months/years out of it. But be aware, it is live circuit if connected directly to mains and has DC output to bulb, use 230V 50Hz or 240V 60Hz, I don't know if it works on 100-120V.

author: Kjelt
author_rank: Super Contributor
timestamp: September 07, 2013, 09:35:21 pm
content: Thanks for sharing, if the filament has burned through (the resistance wire between the two poles on one end of the fluorescent tubelight) it is pretty hard to ignite it. Causes are mainly too old tubes or bad drivers (dimming drivers tend to kill the filament prematurely due to higher current when the tube is dimmed < 10%)But fluorescent tubelights are only $5.- a piece and last 20000 hours with a decent driver, I mean come on..... just buy a new tube.

author: IanB
author_rank: Super Contributor
timestamp: September 07, 2013, 09:59:08 pm
content: Quote from: Kjelt on September 07, 2013, 09:35:21 pmJust FYI, this common phase is actually "I mean, come on..."

author: bilko
author_rank: Frequent Contributor
timestamp: September 07, 2013, 10:59:03 pm
content: Quote from: Kjelt on September 07, 2013, 09:35:21 pmIn some countries, fluorescent tubes are not always available and cost considerably more than $5.

author: Psi
author_rank: Super Contributor
timestamp: September 07, 2013, 11:14:24 pm
content: Who needs intact filaments when you have a tesla coil?

author: onlooker
author_rank: Frequent Contributor
timestamp: September 07, 2013, 11:15:13 pm
content: $5? That is interesting. One would think they all (or mostly) are made in China; There can't be such big difference in price anywhere. In the USA, they can be bought ~$1 a piece regularly, unless you are talking about specialty bulbs. In fact, I have bought some from Lowes for about 50c a piece (on sale price).Anyway, there is hardly any economic reason to fix the bad bulbs. But, I do wonder whether it worth the effort to harvest the electronic components.

author: SeanB
author_rank: Super Contributor
timestamp: September 08, 2013, 10:14:51 am
content: Chinese lamps are in the most part pure junk, there may be some good ones but most are cost cut to an extreme. The ones made in Indonesia and Singapore and other South East Asian countries are a lot better, and the best are made in Europe. USA made ones are not bad, but they have dropped in quality as the production moved to cheaper labour places like Mexico.Best lamps I have were made in Hungary, and the ones made in Poland are as good, made by Phillips in the old Tungsram plant there.Worst currently are the batch of Radiant branded lamps i have at work, but as I have gone through a typical 2 year stock if they were Osram or Phillips in a 4 month period they will not be there long. Almost as bad are the Applo lamps i bought as I needed a few tubes, about 30 % go mercury starved in a few days, some of one batch did 5 years but most barely did a year.Just remember that with the voltage multiplier used there you will have a black ring at the negative electrode within a hundred hours due to ion migration and it will destroy the anode end fast. But for a dead lamp still holding vacuum it will give a good amount of extra life. I have tried some on a neon transformer, they light as long as there is still wire into the envelope, though it only lasts until the glass burns a hole through.

author: Tepe
author_rank: Frequent Contributor
timestamp: September 08, 2013, 11:27:35 am
content: Quote from: onlooker on September 07, 2013, 11:15:13 pmWow! I can't even get a candy bar for $1.

author: amyk
author_rank: Super Contributor
timestamp: September 09, 2013, 08:29:51 am
content: Interesting, it's basically running a regular fluorescent tube in CCFL mode.Quote from: SeanB on September 08, 2013, 10:14:51 amThe circuit is "manual AC" - you have to remember to flip the tube around regularly

author: ResR
author_rank: Regular Contributor
timestamp: September 10, 2013, 04:43:51 pm
content: Quote from: SeanB on September 08, 2013, 10:14:51 amI checked that theory too accidentally, almost brand new 1989 LB-36 T8 that had one of the pins broken, I didn't notice any catastrophic electrode vaporizing within 2 months of use, although I really hoped to see it go black at one end, only slight darkening as normal use would create in soviet era bulbs. It looks like the bulb gets lower current than normally, because it started to get dim at one half of the tube when getting warmed up. Currently I have dead LDC-40 T12 used over 3 months and it still keeps on going. Also it is not exactly a smooth DC, more like DC with 50Hz modulation. Also GE Polylux XL 36W T8 840 don't like the circuit - refuses to ignite and stay on, I suspect it works only with older types of bulbs, that has little bit more mercury than those new "eco" bulbs.

author: SeanB
author_rank: Super Contributor
timestamp: September 10, 2013, 06:43:06 pm
content: The problem with the T8 lamps is they need a higher voltage to start them, as the gas pressure inside is higher than the T12 lamps use. You will be better off using the choke ballast in the power lead instead of the 60W lamp, so it drops AC voltage, but to start the tube it gets the full voltage. As well wind a starting strip onto the lamp connected to ground, so the voltage gradient between the electrodes and the outside is higher, you do need the grounded strip with the eco lamps.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: September 10, 2013, 09:08:02 pm
content: If you hold a flouro light near a strong RF field it will glow.No wires needed.

author: G7PSK
author_rank: Super Contributor
timestamp: September 12, 2013, 05:51:16 pm
content: Tubes light up when placed under power transmission lines.http://youtu.be/a4Oc12e7JPk<iframe width="640" height="360" src="https://www.youtube.com/embed/a4Oc12e7JPk?feature=player_detailpage" frameborder="0" allowfullscreen></iframe>They also light up if you put them in the micro wave, I have put 4 inch ones in and they are insanely bright for a short time.

author: Kjelt
author_rank: Super Contributor
timestamp: September 12, 2013, 08:03:12 pm
content: Yeah radio amateurs could test their transmitter with them.

author: edpalmer42
author_rank: Super Contributor
timestamp: September 12, 2013, 11:26:28 pm
content: As I understand it, any gastube (neon, fluorescent, xenon, etc.) can be fired by voltage across the tube, RF field, electric field coupled through the glass, or voltage spike with help from a filament to preheat the gas. Different types of bulbs are optimized for different methods, but as this idea shows, you can sometimes use one of the other methods. Once the tube fires, you typically need some form of current limiting to keep the thing from overheating since an operating bulb kind of looks like a bidirectional zener.Ed

author: Stonent
author_rank: Super Contributor
timestamp: September 13, 2013, 06:26:56 am
content: Quote from: IanB on September 07, 2013, 09:59:08 pmSome people just talk dead come on.

author: bitwelder
author_rank: Super Contributor
timestamp: September 15, 2013, 09:16:42 pm
content: Quote from: ResR on September 07, 2013, 08:35:30 pmHmm... so, how much power are you wasting in that ballast, compared to the power used to light the fluorescent?

author: ResR
author_rank: Regular Contributor
timestamp: September 19, 2013, 02:35:27 pm
content: Quote from: bitwelder on September 15, 2013, 09:16:42 pmI have no idea actually, if there is a 60W light bulb in series with the tube, it glows in half the power than normally, if there is an old ballast, like I did last time, it barely gets warm. The heat generated depends on what to use to limit current, capacitors seem to have some effect too doing that. Also the tube is not in full intensity, so it's more like experimental, but practical use is possible, for example as a night light.

author: Sylwerdragon
author_rank: Newbie
timestamp: October 07, 2013, 08:02:35 pm
content: well maybe you can use it or it will work but i'm not sure if it is goo idea. It is same with very old tv. yes you can watch it but you know quality isn't good and all that stuff going out of it will kill you for sureGet you light bulb or get Led light tube and that is it

author: Zsola
author_rank: Newbie
timestamp: October 12, 2013, 09:31:51 pm
content: If you want to use dead CFLs, you can check this website:http://skory.gylcomp.hu/fenycso/fenycso.html(Skori designs very nice electronics, like the high efficient resonant power supply.)You can use an electronic of a broken compact fluorescent bulb it the wattage is similar. The key is the high frequency, as Tesla said