Let's start this video with a demo of the device we're going to be looking at are not looking at too much. In fact, it's a cold cathode UVC tube and it's matching power Supply: A Royal Power supply that runs on 5 volts about 400 milliamps so roughly about two Watts for the whole circuit. I'm going to turn this off now because uh, am exposing myself to UVC B it's stinking of ozone one moment, please. So before I turn this off, I'll point out 5 volts about 400 milliamps.

Very consistent, very accurate, and that does equate to roughly two Watts which is useful to know. It's interesting to note that these are the power suppliers that's the first ones I've seen in this format with surface mount and it does say on the front in small text 5 volt 5 watt but that's probably because it can actually drive two tubes in the output now. I Can cut straight to the chase here because it's a bare circuit board. So I've been able to take a picture already.

so let me bring in exhibit number one. It is the interesting bit. it's the cold cathode power supply and it has the incoming Supply It's got an inductor as supplied. Incidentally, it came with a unterminated USB lead, a bit of heat shrink and the connectors.

for this. It gives you the option of either using just the connector on its own or to get instant results. Uh, soldering it to the USB lead well, semi-inson results. We have an inductor, which is an important part of the Royal Oscillator circuit.

We have the Transformer that steps the voltage up and we have the output connector and on the back of the circuit board. I'll zoom in a little bit more than this. We have the classic Royal Arrangement We've got two transistors switching to the negative side of the circuit. We've got a capacitor across the primary not quite 100 sure what that is I think it's to assist with transistor speed of switching off and then we've got a couple of bias resistors.

3.6 K We've got a capacitor in the input Uh 109 I think I know is that one mic, one microfire? this is 100 Nano and a tiny capacitor in Sears the tube in the output and it's designed to take two drive two troops and each one would have capacitor and Sears with it. You can't just put cold cathode troops in parallel because the first one to light would be the one that just then clamped the voltage down. So what they do is they put a capacitor in the series that also lets them program the current through the tube. Okay, let's bring in the schematic.

Straight to the chase here. This is going to be a short video. Here is the schematic: I Tried measuring this capacitor I even took it off board because I was my meter was not getting a good measurement I Tried it on one of these little Universal component testers and it just didn't recognize it was there at home. It's extremely low picofard, probably in the region of one to ten picofired if that.

So the incoming 5 volt supply has the one microfarad capacitor across it. There is a 120 Mega Henry inductor because I did take that off and measure it. and then the Transformer has the center top primary winding. It's got a feedback winding and it's got the secondary winding.

the high voltage winding. The inductor feeds the center of the Prime primary winding and each side of the primary is Switched down to the negative rail or the zero volt rail by a standard Npn transistor d882 To buy a set, there is a connection to the same point as the Uh, the primary with two 3.6 000 ohm resistors going down to the base of each transistor. and then there's a feedback winding between the two that Uh alternatively pushes in pools that whichever one starts up first, it's a sort of avalanche effect. It will just start oscillating backwards and forwards.

The output of that then goes to the secondary is limited. The amount of energy can put through in each cycle to the tube. Do not connect tube directly across with that capacitor circuit. It makes the transistors get very hot.

I've done that in the past and it did it was. It just sank as much current as it could. You need that capacitor there to limit and the reason it's a low value is because it's very high frequency and it's very high voltage. so it doesn't have to be a high value of capacitor and there is a atmosphere is 100 nanophary capacitor.

I've seen this a lot in oscillator circuits across a maybe it's forming a tank circuit, an LC circuit with the primary, but that is more or less it. It's this implementation of the standard cold cathode driver that you used to get inside PC cases for the colored tubes, and likewise, this will actually drive those. The thin tubes are much harder to drive them thicker tubes because they effectively have a higher set of resistance to current flow. Uh, this one is interesting.

It's true because they've folded it around, but I think they've actually the pinch at the end here. think it's actually fused together slightly. not sure that would give extra strength and it is called cathode. There's It's not like a fluorescent tube, it's driving it like a neon tube which is quite hard.

but that's a just how these are designed to be driven. And it's possible that you could use this same circuit to drive a neon ornament and not sure how much tube it would drive. but it should drive at least a couple of feet of standard diameter tube. but at two Watts it's not going to be super bright, but that is it.

I Shall provide a link in the description down below for where I got this from. um, it came from AliExpress but I Shall provide a link to the listing in particular, because it's quite interesting. It's also worth mentioning it's absolutely stinky of ozone. so the thing is not just putting out the 254 nanometer UVC, but it's also putting at 184 nanometers.

So it's very pure quartz glass or Uvl glass. and uh, it's got a very high output and both wavelengths, and it certainly has that effect of instant sterilization and ozone. It's quite a neat little circuit.