Fluorescent lamps, electronic vs. glow starters

Experiments with some fluorescent tube fixtures with traditional magnetic ballasts (iron inductors). Comparing standard glow switch starters with an electronic starter, exploring what's inside. Reverse engineering the electronic fluorescent starter schematic and explaining how does it work. Some oscilloscope waveforms. Thanks for the donated electronic starters ;). Correction: they turn on after 1 cycle, not halfcycle.
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[@CliveChamberlain946]

Those close-ups at 4:30 are a "thing of beauty" Dude your patience and camera skills are top notch! 🥰 I'm a hopeless addict to this channel 😁

[@DiodeGoneWild]

Thanks so much! :)

[@joinedupjon]

Yeah I think you should do a youtube short of several types of glowtubes in close up - I'd watch it on loop and feel happy

[@pritambissonauth2181]

Hey, this electronic starter is made in my country, Mauritius, thought we did not manufacture anything over here . . .

[@samuell.foxton4177]

I just noticed this as well… didn’t know Philips had a factory in Mauritius

[@peaceandlove5855]

i did ask for such video before , thank you so much , you are the best keep going

[@RixtronixLAB]

Nice info, thanks :)

[@jacknedry3925]

My god, the electronic starter is ridiculously complex.

[@aleksanderwojtczak8582]

Spoko koleś jesteś.

[@WagTsX]

I really appreciated this explanation, also learned a lot about fluorescent starters. I am slightly jealous about your collection of those stuff, here in Brazil even fluorescent tubes are "unobtainium" right now. Every light that worn off needs to be replaced by crappy led tubes.

[@Denis7947.]

My school still uses florescent tube

[@Gameplayer55055]

@@Denis7947. ive ever seen a huge soviet box of fluorescent tubes, so my school won't ever run out of them

[@LaLaLand.Germany]

Good for You but I think You missed the point: He cannot get any. Doesn´t matter if Your school uses them- He cannot obtain any neon tubes in his point of the globe at the moment. Ship some to him if You really want to help.@@Denis7947.

[@Denis7947.]

@@Gameplayer55055 lol

[@CAESARbonds]

Then you need to collect used ones. Sometimes the ballast is worn but the tube is still good and vice versa. If they get replaced als for some used ones. Then you can start a collection

[@Shmbler]

I have to say: These closeups of the bimetal starter in operation were pure ASMR. I wouldn't mind watching it for an hour.

[@mikemccormac9368]

Finally after years (50 or more) of fascination of low and high powered electronic circuitry, your video has finally brought me to the understanding of the functioning of fluorescent lights😄. Your ability to convey knowledge in an absorbable way is remarkable. I love the way your cat treats like a muddleheaded student requiring the occasional encouraging prompt😅

[@antibrevity]

Excellent video with lots of information and demonstrations. This is why I love this channel! I've understood the principles of how starters work for many years, but watching these bi-metal starters operate simplifies what can seem like a complex circuit. I'd never seen inside of the bulb type of starter before this video, so thank you.

[@DrHouse-zs9eb]

Im always impressed by your makro recordings. Ive never seen such in detail video of a neon starter.

[@iamdarkyoshi]

Manually shorting out the starter contacts explains why my dad's retractable shop light had a momentary switch on it that you had to press to start it :) Also as a kid I loved the noises the glow starters make

[@LMB222]

Ding Ding Ding Ding Diiiing!

[@superdau]

I got a workbench lamp with a magnifying glass and ring tube from the trash. And it also has two switches, one toggle and one momentary. I was wondering what that would do, when I saw it. I also thought something was broken, because the lamp didn't turn on with the toggle switch. Only when I was looking for the starter, as they are the usual culprit for non-starting tubes, it "clicked" for me. It feels like in the ancient times, where I remember my uncle having to preheat his Diesel car and tractor 😅.

[@EduardRitok]

i used to start my 70w hps work light this way when I had no functional starter available 😅😅

[@Alchemetica]

This is one cool video. Watching the contacts come together then separate in the starter I have never seen before this video. You answered many questions on how fluorescent tubes start and once started run bypassing the starter.

[@erikziak1249]

I have very unusual fluorescent lamps from old streetcars. They ran at 300V DC in series there, so always two lamps failed, never a single one (or an odd number of lamps). You might know the legendary Tatra T3 trams, but the lights I have are from a K2 tram, which is the articulated version. I initially got them for free from old trams that were sent for modernization (they never had those lights afterwards) a few decades ago. I used a ballast and starter, but later reused electronic drivers from dead fluorescent bulbs. It was the filaments in the bulbs that failed after about 8 years, not the electronic circuit. So I botched it to the big streetcar lights and they work fine ever since then (about 10 years now). The upside is that they light up instantly and do not flicker. I remember dumpster diving for old fluorescent light-bulbs, as I knew that the electronics inside some of them (I focused on Philips 22W) was perfectly fine in driving the 25W tubes used in streetcars. The only problem is, those tubes are quite atypical length (1 meter), which cannot be bought commercially and I have to source them from old streetcars that are being scrapped (commercial lengths are 0,6 meters and 1,2 meters). The problem is that worn out tubes rarely work properly. In streetcars, where they run on 300V DC they work, but not always when I try to run them. Fun fact: The streetcars have a polarity reverser that periodically reverses the polarity on the tubes to ensure even wear of the electrodes. Older series relied on the driver regularly switching the lights between the two "ON" positions that were either side of the "OFF" position, usually at terminus stations. The funny thing is, that I had to completely rewire the streetcar lights in order to make them run. The original 600V rated cables were a super thick rubber insulation with a super thin copper wire inside. Very unusual in comparison with regular 230V "household" stuff. I still have four of those lights in my garage and they work without problems. Another interesting thing: The light fixtures did have resistive heaters running alongside them next to the tube to make sure those tubes would light up even in harsh winter conditions at temperatures of -40°C. Those heating elements were about 1 cm away from the tubes and ran in parallel to them. I do not remember how they were wired, it is about 20 years since I modified them. Maybe even longer. I have some spare electronics drivers and one spare tube that works, but give the reliability, I do not expect to need any of them soon. I wish I had gathered more of those lights and drivers 20 to 15 years ago, when those streetcars and bulbs were massively being replaced by more modern things.

[@johnwelbourn3811]

What an amazing video. I used to work in a hospital, illuminated by hundreds of fluorescent tubes, a significant proportion of which were permanently blinking, obviously using the old style starter. I had a good laugh at the mains voltage breadboard btw.

[@lukedavis436]

I preferred the flickery startups personally

[@javanpannadi]

​@@lukedavis436me too., bond is stronger with that one huh.!

[@davida1hiwaaynet]

Very nice demonstration. I really like old fluorescent lights because they seem to last a long time, and remind me of better days before all of the far East poor quality parts we are forced to use now with LED lights. My shop has all fluorescent lights but they are North American spec T12 high-output lamps, with a more complex ballast. These ballasts have been unavailable for years. I have been removing the potting compound and replacing the worn out metal film capacitors in them to keep my lights working.

[@ZaneDaMagicPufferDragon]

I love ❤️ these longer videos!!!! I learned so much about fluorescent lights from this!!! Thanks 😊 again for sharing your great content!!!

[@cisarvialpando7412]

Finally on the topic....gas discharge lamps.....stupid LEDs destroyed the market..

[@harrymartin1661]

As allways very interesting and good explained! Wonderfull video from the "Start"! Fluorescent Tubes are forbidden in germany since september 2023. You can only use old ones but not buy new ones.

[@liam3284]

Some very old fixtures had a manual preheat switch. I have also seen one model of stater that used half-wave rectification to saturate the ballast, rapidly heat then cut off to hit the tube with a whopping great spike.

[@adriansdigitalbasement]

Super fascinating! I always wondered how the old starters worked. I am curious here in 120v land, can you run a tube with just ballast and starter like you can in 230v places? I don't know why I always thought they had to use a transformer too to step up voltage...

[@eDoc2020]

We need transformers for 4ft and larger tubes, but for 2ft and smaller tubes the traditional circuit works fine. I remember there was a dark windowless bathroom in the old wing of my middle school. I liked arriving when the lights were off because then I could be the one to watch them turn on. Actually I'm sure most of the time I just turned them off and back on. More recently I noticed a fluorescent wall light clicking and failing to strike at the local library just this weekend which surprised me. The light was installed when the building was renovated around 2004 so I would've expected an electronic ballast.

[@uploadJ]

@@eDoc2020 re: "for 4ft and larger tubes" 4ft tubes strike just fine on a 120VAC 60 Hz circuit here ... at TI they used the very long single contact per end in the overhead lights, but then they also had access to 480 V multiphase mains too.

[@eDoc2020]

@@uploadJ I just looked at the ANSI C78.81 document and a 48T12 lamp (of the American variety) requires 176-230 Vrms between lamp terminals to start. With the inductive spike of a mechanical starter this could work but it would likely take several tries. The more important problem is that the nominal lamp operating point is 101 volts which is getting pretty close to 120 volts. The lamp power would vary an unacceptable amount with line voltage fluctuations, temperature, etc. We obviously do have 4ft tubes run from a 120v source but the difference is we do not use a simple series inductive ballast like shown here. We usually use a "rapid start" ballast which is a more complicated step-up transformer with integral current-limiting. These have extra windings to directly heat the filaments and do not use starters. The reference ballast is equivalent to a 236 VAC supply and a 439 ohm current limiter. The 8ft long tubes with a single contact on each end are instant-start. The reference ballast for those is equivalent to a 625 VAC source and a 1280 ohm current limiter. They rely on this very high voltage to start without preheating the cathodes.

[@twocvbloke]

A bit late for halloween now, but using a fluro starter in series with an incandescent bulb produces a nice "scary" looking faulty light, ruins the starters, and probably the bulb too, but a neat effect for cheap, or at least it used to be 'til standard bulbs and starters went up in price... :P (EDIT: And of course, such a thing was demonstrated in the vid had I waited to comment!!)

[@foreigncontaminant2015]

yep, did that when I was a kid!

[@mernokimuvek]

I always enjoyed the glow of starters and sometimes removed the cover to see the glow. They also make a nice christmas lights blinker circuit.

[@Fernando_S]

I accidentally learned how this works when I was a boy (maybe 10-11 years old) and used to play with starters and iron ballasts connected to batteries or small power supplies from toys. The iron ballast gave me some electric shocks when I disconnected the power supply. I got intrigued why it happened while disconnecting (insted of connecting) the power supply, until I learned what an inductor is and how it works.

[@Leon-ts1nl]

It's the neon lamp that makes that ding sound? I always wondered

[@DiodeGoneWild]

Yes, the contacts in it separating

[@Alexelectricalengineering]

I absolutely love your long videos. I was always thinking the capacitor is for interference suppression, I learned something new. Thumbs up 😎

[@BudTheDrummer]

In the '60's and '70's I had some florescent 2' and 4' tube fixtures. They all used big heavy ballasts and starters. The starters had a hole in the top of the can where you could see the light from the the electrodes arcing as it started the tube. If the tube wouldn't light and there was no glow from the hole, you knew the starter was bad.

[@DiodeGoneWild]

Wouldn't an open filament appear the same?

[@andyapple9]

You are the best teacher of electronics I've ever had. Period.

[@cosmefulanito5933]

The capacitor in the starter is set to reduce sparking on the contacts. This way they last longer.

[@1pcfred]

So, like an ignition condenser on an engine? But like Dan says the blinks are also slower with the capacitor.

[@cosmefulanito5933]

@@1pcfred Yes. I don't see the difference in blinking speed with or without the capacitor.

[@davidknightaudio934]

I agree i think its there to stop arcing and welding of the contacts but thinking about the mode of operation he might also be right we need to work out what exactly makes the contacts open up is it just because when they short the heat inside the starter dies down and thet open or is it welded and relies on the capacitor obviously the arc cant form that ignites the tube till the contacts open so that rules out the tube pulling down the current having anything to do with it apart from stopping the starter warming again

[@mernokimuvek]

It also carges to the voltage inductively generated by thew ballast and stays ata higher voltage for a few milliseconds.

[@uploadJ]

re: "The capacitor in the starter is set to reduce sparking on the contacts. " Arcing - it reduces the 'gas plasma' that forms, which works against getting the main tubes to 'light up' (note: The Neon tube is in parallel with the main fluorescent tubes.).

[@atmel9077]

I prefer the inefficient hazardous waste to the stupid LEDs because it turns out that the inefficient hazardous waste is replaceable and recyclable. IMO the only legitimate use for stupid LEDs is in LED strips, because the LEDs are spread across a wide area, so they do not overheat, and they are replaceable. LED light bulbs are an incredibly stupid idea, because putting so many LEDs and electronics in such a small device makes them run very hot and have a very short lifespan. Modern LED light bulbs often use a stupid buck regulator, they should instead use a linear regulator which could be made out of 1 bridge rectifier, 1 transistor, 2 resistors and 1 zener diode, and a capacitor to prevent flicker. Should the capacitor fail, the light bulb will flicker but should continue working. They should also have a large aluminium heatsink with fins, which very few LED bulbs have.

[@AmitabhAnkur]

Is the antenna thing is capacitor? In old starter? Edit: got it.

[@ville_syrjala]

And sometimes the compensation capacitor is a RIFA and it stinks up the whole place for several days after it spews its guts.

[@paulkocyla1343]

Like you just showed with the traditional starter in series with a lightbulb, that´s how we simulated a bonfire for a school theater stage on a budget

[@MassimoTava]

Every horror movie scene only uses these lamps

[@309electronics5]

Or just the starters

[@EJEuth]

Eco-Friendly or Harmful stamps can be more volatile than a “Freon”.

[@janno288]

I love your videos! Every time you post a video it makes my day complete! (especially when its about older glas tube based electronics)

[@amkp40technology]

*Nice explanation ❤❤*

[@rsaj-cq6ne]

Nice video. Thanks for explaining something not obvious and not written everywhere. Your assumptions looks perfectly correct. What the threshold voltage of jc1? Thanks

[@DiodeGoneWild]

The JC1 diode drops 0.6V measured using a multimeter. Just slightly more than 1N4007. But of course, at a higher current, it might drop close to 1V.

[@rsaj-cq6ne]

The only thing i dont get is when you use the electronic starter in series with the 60w bulb and P0130AA goes in conduction mode and stops conducting only when you disconnect and reconnect. Did you understand why this happens? Because if P0130AA is conductive due to 100uF cap charged at 0,6-1v connecting and disconnecting the circuit shouldnt interdict him.

[@poptartmcjelly7054]

My grandpa used the old style flashers to flash his string of incandescent xmas lights

[@haajee1]

The old Philips starter. Made in Holland. From the time when Philips was just a big company and we in the Netherlands could be proud on it. Company is complete distroyed...

[@309electronics5]

Yep! The brand does still exist but the real phillips is long gone! Kind of sad that they just vanished now and their name gets used by other companies.

[@haajee1]

@@309electronics5 Yeah, and the quality of the products of the last years was very bad... And the last real Philips devision Philips Medical has killed itself by a scandal of CPAP devices. But it bring also new nice companies light Signify (formerly Philips Lightning and ASML of course :)

[@piconano]

I like the in-depth video. Learned a lot thanks to you.

[@techtinkerin]

I remember rubbing the tube with a cloth to get them to start😂

[@EJEuth]

👍 Nice investigation of the classic fluorescent starting system - something from my childhood times. Thank you for sharing! 👏

[@a.lisnenko]

Huge thanks for showing how flouresent lamp starter works!

[@حمیدتاجیک-ش9ك]

Fluorescent lamps, electronic v

[@arccraver]

Thank you for providing us with great content!

[@DiodeGoneWild]

Thanks for your support ;)

[@555-xd1fo]

Solid state starter

[@manueldi_77]

Your channel is awesome. All the various topics you cover and all the detailed explanations are outstanding. ❤

[@superdau]

How do you get those macro shots done? They are beautiful! I'm wondering especially about the large depth of focus, which is hard to get on macros. Where's the clicking sound of a starting fluorescent tube actually coming from? I always though it was the starter making/breaking contact. But from this videos it seems that there's only a "ping" when the lamp actually strikes (or at least flashes) and not every time the starter makes/breaks contact.

[@Valtra103]

15:35 PTSD from school. I wish they blinked and tried to start only a few hours... In reality i had to sit under blinking and buzzing lights for months. I hate those lights with passion.

[@beatrute2677]

Thanks man, learnt heaps from this one

[@tajtrlik1111]

Veľmi pekné video s vysvetlením princípu činnosti žiarivkového osvetlenia a video mi vôbec neprišlo nejako veľmi dlhé, takéto aspoň pre mňa zábavné a poučné videá kľudne môžu byť aj dlhé a aj tak neprestanú baviť, lebo je tam spústa zaujímavých a užitočných informácií a tiež tu boli pekné experimenty a zaujímavé závery vyplývajúce z týchto experimentov. Tiež sa mi veľmi páčil ten záber zblízka na ten štartér, ako sa pri zapálení tej dútnavky pekne k sebe tie elektródy približovali a potom výboj zhasol a nastalo nažeravenie žiarivky a potom jej zapálenie, toto bolo v tomto videu tiež pekne ukázané.

[@Dino-1958]

I miss the pinkle pinkle sound and the blinking when using electronic starters! 💐♥️🧀😎🐈‍⬛😹🏳️‍🌈🏳️‍⚧️🇪🇺🇺🇦💐

[@Cinncinnatus]

Well.... Actually...not all inductors are Ballast Chokes, but all Ballast Chokes are inductors.

[@Skracken]

The wiring system you talk about is, I would guess, some variation of the TN-C system, where Neutral and Protective Earth is the same conductor

[@pizzablender]

That electronis starter says "Made in Mauritius". And Mauritius is even more unlikely place to make something: an island republic about 2000 square kilometers. - so that is 40 x 50 kilometers only.

[@marcellucassen8033]

Even a simple lamp has a lot of technology in it and most people have no idea.

[@burtharris6343]

Thank you, I have long wondered about the old tube starters.

[@Lolteba_19]

Electric game

[@bluerizlagirl]

When I was at school in the 1980s, money in the educational system was so tight, we were limited to one light starter per classroom (all old-style glow starters). Every afternoon in the Winter, somebody would be given the task of climbing on desks, reaching up and inserting the starter into each light fitting in turn to start the light. It sounds crazy today (even more so, considering the temporary blinding effect of the tube bursting into life while you were standing precariously on a desk), but it undeniably kept the price of school meals low across the county, so maybe it was actually worth it ..... After I left university, one of my friends lived in a flat with a faulty starter in the bathroom light, which had to be twisted in and back out again to make the light come on. I guess the faulty starter must have been short-circuit.

[@sadikalarieski7340]

Jumper spark it. 2-3times also work. That old ones is beauty you can clearly see what going on inside the tube ❤ Edit: oh yeah ofc he did it 9:39 😂

[@SOURADEEPBISWAS]

Awesome informative video. I became nostalgic coz my childhood was with these fluorescent tubes & myself always tinkering the circuitry of them to understand the usage of ballast & starter!

[@bentboybbz]

Maybe you said it and I didn't hear it but doesn't it heat up the small amount of mercury that gets a few ions flowing and then when it switches the spike along with the flowing ions jump starts the tube and is enough to put it into continuous flow so to speak? I'm not super familiar with these, but I assume they have moved away from tubes with mercury, if so how do the new ones work? And what is contained within them? Thank you for your time and effort! If anyone knows and doesn't mind explaining to me I greatly appreciate your time! I hope everyone is having a great day or night! Edit...I'm at work and I have bad hearing so this may have been explained in the video but between my hearing and his accent i may have missed...i have definitely missed information lol

[@jutukka]

I have one electronic starter and the TN22 has failed twice in one year. I have opened the starter and replaced the TN22 and then it works again. I don't know what kills it. Any suggestions?

[@janzahradnik8089]

I have one question. When the main thyristor full open, makes short circuit via diode SC1 and damaged the fuse.

[@timhartherz5652]

Isn't the capacitor supposed to be in SERIES with the ballast? Never seen one in parallel n the wild.

[@Not-jeb]

Is flurocent tube light still available?? It almost impossible find nowdays

[@johnrehwinkel7241]

While the capacitor does have an interference suppression function, my thinking is that is not its main reason for existence. It doesn't have nearly enough value to keep the contacts closed briefly, that's accomplished simply the the thermal mass of the bimetallic strip. I think the main reason for the capacitor is to route the high voltage starting kick from the inductor around the gas tube, so it doesn't conduct and draw current away from the lamp.

[@German_byte]

Can you make a video showing how a fluorescent light can be powered by a 6 volt battery?

[@ford1546]

Hello. Can anybody help me? What happens when a fluorescent lamp is worn out and flashes and won't start? Will an electronic safety starter protect and turn off the fluorescent lamp without damaging the starter? Or will the thermal fuse in the starter blow and then the starter is useless?

[@cool386vintagetechnology6]

When I have a starter with welded contacts I connect it to a 10A power supply and blow the short apart. I was always under the impression that the capacitor was to reduce RFI, since a fluorescent tube is effectively an arc lamp. If the capacitor is shorted I cut it out of circuit.

[@michvod]

Elektrokovina is still in business, producing electric motors and pumps ;)

[@wolfrobben6914]

Very interesting. I always wondered why the lamp flickers at start up, but never wondered enough to investigate a starter. The simple mechanic principle with the bimetal strip is absolutely awesome. Its a game of hazard - but sooner or later, it will trigger the lamp... Great content!

[@maheen-]

4:57 thats a good close up portion. I will use this to make a boot animation for Android phones and send it to the Android Community. They can use it with costom roms.

[@andytipping70]

could the mystery diode be a diac?

[@DiodeGoneWild]

Not a diac. A diac triggers and then has way lower voltage drop. It's a Zener diode or a transil, it keeps a constant voltage drop.

[@sodium.carbide]

with these kind of knowledge, one can easily predict your age..

[@senorjp21]

I have some old flourescent lamps where the on/off switch is a push-on/push-off but you need to push and hold to ignite the lamp. I guess the power button has two switches in it - one in series with the mains and one parallel with the tube.

[@uploadJ]

Ya - the old 2-lamp desklamps that used to be used throughout offices had this arrangement. Watch the fifties movies and not the lamps clamped to a desk edge ...

[@maxiflow8695]

En argentina no se vieron estos arrancadores electronicos por todas partes como los arrancadores comunes...directamente pasamos a las "bajo consumo"...lo que sí se vió fueron los balastos electronicos..de paso...extraño las lamparas de filamento

[@kasel1979krettnach]

so when I have no starter on hand, I just install a second, spring loaded light switch and use it for starting ? that makes a lot of sense in fact

[@steve-h7z]

I've done some testing with some Hid bulbs, and these seem to start the bulbs!! 😀

[@CRAIG86]

I love gpow starters, Wana know why? PING PING PING PING

[@Joetechlincolns]

Cold cathode instant start Fluorescent lamps next video?

[@chikokishi7030]

This is a great channel... The accent is charming and fun as well

[@Smajchl]

i think the capacitor is there to save the bimetal contacts from errosion like on oldschool car ignition

[@worroSfOretsevraH]

We used to use starters for christmas lights. They lasted forever.

[@MegaBlueBomber]

Tinga tinga ting, it feels as if the starter bulb has a mind of it's own. Like someone using a striker to start a fire

[@monad_tcp]

oh, sometimes I miss the sounds and the kind of light emitted by such lamps

[@CAESARbonds]

So in a pinch i can manually ignite a tube. Thanks is for the info.

[@armunro]

Its such a wonderfully reliable design. Fair due to the people that developed this and made it so reliable.

[@elfnetdesigns702]

seems easier to just replace all the internals with a modern electronic ballast

[@vardenispavardenis1949]

I have never seen a screwdriver with a resistor(?) inside of it. Very interesting!

[@0Light6and3documentary9]

Hi, thank you info test😊 starter electronic & neon standard , collection ?

[@toribowman5116]

Usually when it gets to like 1000s of watts it starts to heat up

[@akosv96]

Starter bälb 😂

[@j7ndominica051]

I love the glowing eyes of Catculator.

[@kapegede]

Your macros of the igniter are awesome! This should be a reference!

[@TheRailroad99]

Wow... The close up view of the starter was great!

[@devout2Jesus]

The Phillips starter has 5 nF or 10 nF?

[@richardhemingway6084]

It took me years, to fully understand how flourescent lights worked. This video shows very clearly how they work. Brilliant.. I always thought that the capacitor in the starter, was to quench the spark across the bimetallic contacts and provide interference supression. Which would explain why it is missing in an electronic starter. Now I have to figure how some flourescents can be dimmed. Some I have come across needed special tubes with an extra filament in them. But I have seen others that use standard (UV) tubes. I worked at sea and my first ship had DC 110v mains. there was a single flourescent fitting over the projector screen, in the mess room. It had to be started with a push switch. (No AC mains).

[@eDoc2020]

You can easily dim a fluorescent tube "just" by reducing the amount of current in the main discharge. The hard part is the reduced current results in a lower electrode temperature so you often need extra electrode heating. There's no need for a special tube, this can be done in an 4 pin ordinary tube just by applying some voltage across each filament.

[@ricardomenzer]

It's so nostalgic to hear and see the flickering of the starting lamps. It was part of my childhood and was always kind of hypnotic to see them starting!