Good evening fellow lighting nerds  Well, today, I saved a whole box of Philips TLX 20W 640 tubes from being thrown out and just discarded at work. as there are no more fixtures for them around, they were just taking up shelf space, so I saved them instead of letting them go to waste We do still have plenty of 40W TLX fixtures in service, and we do still have plenty of 40W versions of these tubes too, but becuase still in use, I cannot have any of those sadly. But the 20 watters are still such an awesome save - I did not even know that 20W TLX fixtures were a thing honestly.

So my question is, how can I power them up? As I don't have a fixture for them, I want to build my own. I'll have to come up with a DIY solution to tube sockets for them unless you can still buy FA6 TLX sockets online somewhere, but for now, I will just test them with alligator clips. But this brings me onto the question. Is the intended circuit literally just a ballast connected in series with the tube and thats it? These are designed for starterless cold cathode start and operation in EX-luminiares. I guess these have very seriously beefy cathode in order to survive that sort of starting abuse, or maybe they were not meant to be started often, and just left on? They have a large ignition strip, presumebly works best with a grounded metal backplane. But because these are so short, I am thinking they will just ignite capacitively even in mid air. would these use standard 18-20W ballasts or are they intended to use some weird autotransformer ballast that ups the voltage for starting easier? remember, we use 230V mains here, so a pretty good starting voltage. you can make 18W tubes self-ignite here with a grounded backplane, I have done it on accident the tube strikes before the starter gets a chance to try preheating sometimes in my small 18W bench light, haha. 

but yeah, if anyone here has an actual TLX fixture, and knows the wiring layout, that would be awesome. I'm thinking about trying a few on the bench with some standard 18W ballasts to start with

I am almost certain these run with standard preheat ballasts just without the ignitor connected. Traditionally they used special ballasts specifically for hazardous locations that were built very robustly, but had the same specs.

The better ballast for these work like an instabt start curcuit, with high OCV. However my GDR fitting that uses these just has two beefed up chockes to run them.

After reading some other posts here on LG, and also thinking a little and asking around, it appears you guys are right they only need a ballast in series like I thought, and should strike fine here on european mains voltage! I have plenty of 18W ballasts, so definetely stay tuned for experiments with these I'm gonna power one of them up as soon as I have some free time on my hands And I think I have just the thing to make a fixture for these too! my only question is sockets, but I will figure something out once we get that far. Lighting one of them, or a few of them up on the bench should be easy though, they literally just need a ballast in series. a regular old 18-20W ballast will do just fine. No starter needed. No high OCV needed. These being shorties also helps a lot with striking too, so I definetely won't need any higher OCV to strike them. Not even the 40W ones seem to need anything other than mains voltage to work, so thats awesome! These are the simplest fluorescent tubes to use ever

I am excited. Also need to organize some other new tube arrivals into my stash, hehe My workspace at home is very messy right now haha.

These TL-X 20W tubes strike up so easily that you should even be able to run 2 in series on a single 36/40W ballast.  That would also deliver much higher system efficacy due to the lower losses than using 2x 18/20W ballasts.