While digging through my workshop, I came across an old fluorescent light module out of a same box and I Thought it'd be interesting taking taking a look at it because although it's not quite vintage yet, it's going to be vintage soon because these things have been replaced completely with the strings of LED modules. So this one has a very simple metal chassis with the inductor on it or chassis if you're American with the induction on it, the chalk as we'd call it here and it's got the fluorescent tube. and the fluorescent tube itself has the starter built into the end. and if I turn this on now, you'll see that it's the old-fashioned circuitry, no electronics.

Well, not much in the real. Electronics when I plug this in, it also blink a few times before it starts so it started quite quickly. But what actually happened in there initially? This little thing in the end: I'm going to turn that light off now because it's far too bright. Initially, what happened was this little starter.

in the end uh provided a current path through heaters to actually heat them up before it's struck and I can take this off just to show the construction. It's very simple. This is the lamp with the starter built in and this is just a simple inductor. It's got live neutral and Earth the neutral was uh, straight to the lamp.

the live goes through. then doctor comes back here, then Doctor and goes to the other end of the lamp and the Earth just goes onto the Chasse Okay, I'm going to zoom back out, but because I'm going to bring in the notepad and draw this down, there will be no surprises to those who are veterans of the electrical industry. I'm just going to team this down a watch me tame it down. just way too much.

Yeah, it's not bad, it's not bad. So ultimately you know this is just a standard fluorescent fitting but just combined into a small enclosure. So the tube itself looks like this. It's a continuous tube of glass and inside that is a carrier gas which is sometimes organ, sometimes Krypton And there's also in the end a little heating element.

The heating element is coated in a thermionic coating and what happens is that when you heat that up it starts emitting electrons and that basically lowers what they call the the cathode drop at the tube and it makes it easier to light the tube. If you were driving this as a knee in tuber, it would be called cathode. Literally just a one electrode to each end and choose Brute Force to get it to start. This makes things much easier.

It means you don't need a high voltage in engines for so the power supply for this the is say for instance here is the neutral and here is the live but via that inductor and the inductor is just used to limit the current through it. Some cheap out systems use a resistor, but the resistor is very wasteful because it dissipates always heat. The capacitors are not good for this because they only spin the tube, strengthen each half cycle, it causes a huge current pulse and quickly damages the Troopers Inductors are the ideal choice for this. and basically speaking as the currents flowing uh through the inductors pushing back against, it's just an efficient way of limiting current fairly efficiently.

Incidentally, if the this has been a perfect fixture, there would have been a capacitor across like that because that is a simple inductive circuit. Relatively simple inductive circuit. However, there was a pin. There are just terrible.

They're just like capacitors and fluorescent fittings are not my favorite thing. So these two other electrons, there's two connections. they come up to another little Globe that's that looking one there. very black and they always go like that.

And inside that globe and I'll just draw an exaggerated size. It's filled with a gas like neon. Define Tuna gas and the pressure to the voltage required and tacked onto one of those electrodes is a little bi-metallic strip like that. and then this little file thing doesn't.

It's not even marked for the volume. I Could measure that I Could measure that right now. one moment, please. It is measured 3.5 nanofarad.

It's purely for suppression because it's across the contacts in there, but we'll contribute to the blackening those contacts. So let's say 3.5 Nano Farad. This one down here would depend on the reaching of the fluorescent tube. I'm not really sure what it'd be, it would just be in sort of low microfires.

Like one or two microfires probably. But this is full of a neon gas and initially, when you power this circuit up, if the trooper hasn't struck the open circuit voltage across, that is the full means voltage, which is 240 volts. So you get in the case of the UK, you get 20040 volts across it and that causes the gas to Glow in this tube. and that quickly heats the bimetallic strip up until it physically touches the other electrode.

And when it does that, current flows directly through the inductor through each of these little heater filaments at the end, through that shunted starter, through the other heating filament, and they start heating up. And because it's shunted itself out, this unit will now cool down, and because it's cooling down, the bimetallic strip will break apart again. and uh, when it does that, the depending where it does it in the same way if it causes a high voltage spake and also because these are heated slightly, they may be a level that the voltage across them has dropped that it can actually ignite the tube. If it doesn't, the cycle starts again.

that just keeps going tap tap tap tap tap tap tap until it lays. If you've got a bad tube that's not lighting, you may find the starter. That's when you'll see it just going. Flash flash flash flash flash and not lighting.

The other thing you'll often see, particularly with tubes like this, is that just glowing orange at the end. If it's just basically glowing orange around the end here, and there's a good chance the starter has welded and something you can actually do for that is just to basically get the base and ping it like that. just give it a sharp tap and that sometimes gets a bit more life out then. But at that point in time, it's your warning that you're going to need a new tube.

Um, and that's more or less anything else worth seeing. I've got the thermionic emissive coating. Get the neon in here. Oh, that's the other thing.

Once it has struck, the voltage across this tube will typically drop to 90 volts. and at 90 volts, the gas is chosen to actually not sustain the conduction of that. But sometimes you might find tubes that actually do light up and then the starter kicks in again. they go out again, then it lights up.

and that is because the voltage across the tube, the electrode Ms of Coatings are basically sputtered off and that causes blackening at the end of the tubes. and uh, when that happens the voltage cross. This is enough to actually make it kick back in again. That starts it think thinks the lamp's not struck but in reality it was and it just keeps flashing and pulsing.

it Make sure you think that maybe the LEDs are a good option, but having said that, you've all seen those signs that are just basically the LED signs with the power supply that's failed and it's doing its flash flash flash. So which was worse? But there we go. These had a very long life. The troops there I mean they lasted an extremely long time, probably more than many of the LED replacements.

But now that the European red tape manufacturers are basically, well, this year I think is the last year they're allowed to manufacture for the national troops in Europe and not sure that's going to go with the germicidal ones, but there we have it. Um, there will be no choice but to go for LED And at some point this trip here is going to become a vintage artifact along with all its circuitry. They're strange how times have changed and what was radically new at the time is just now out of date.