Ah, i do like the cheap chinese strings of led lights, not because they're, particularly pretty i mean they are quite pretty, but because they're always so pleasingly dangerous. So let's investigate a set. This one wasn't too expensive, say it wasn't too expensive. These used to be really super cheap, but you can get equivalent sets from prominent uh suppliers in your country that comply with local electrical regulations, possibly with a low voltage power supply, and that is the better option, even if it costs a bit more, as we shall Explore and find out with this set so for your instant gratification.

I'm going to turn this on, i'm already spotting. It's only two channels: the the cheap cheapskates but uh it comes with a british squarepin plug a non-compliant one because uh it has uh the sleeved pin here the earth pin which it shouldn't have, but i shall plug it in. It does suggest that maybe we're very lucky and they sent us a 224 vote version instead of the previous verses. I've had that they sent 120 volt and they emitted.

Lots of smoke is very exciting. It just ruined the christmas atmosphere, a bit though so it's the horrible controller that you'd expect that you click through the modes and the does that one that looks as though it's a static mode, but then it starts fading out after a while just to dupe you, I think that's it this time and for your gratification. I shall show you these in the dark, noting actually that they're using the sort of golden a leds, that's new for the uh and uh other red ones, phosphor based, not really sure they're, quite nice colors. That is different to the crappy yellow ones they used to do, but anyway, i'm going to dim the lights down now.

So one moment i'm just going to do that right now: oh yeah, very bright and colorful, not too much shimmer, either, though these will almost certainly be flickering yeah. Well, of course, when you actually use the mode i'm not going to do it, i'm not going to torch you by showing the usual struby flashy modes. I'm a bit disappointed these lights were supposed to be. Each strand was supposed to be a different color, but they've actually just uh put them in a single color each time or tell you what as well, it's not just going red, yellow, green blue.

It's actually going blue uh, red, yellow, green blue, yellow blue blue green. It's just random colors, maybe just what they put in at the time. That's very strange, but anyway i'm going to bring the light back so watch your eyes and let's explore so the reason you can see a slight shimmer, possibly if it's not taken out by the processing is because these are actually being run directly across the mains with Just resistors and series the first few leds in the string will have uh resistors in them dissipating a bit of power and the worst mode you can set them on, and i can almost always smell that plastic right now. The worst mode you can have the one is static, although that's what i would call the best mode.

Oh, that's that rather scary, one, a bit wire, stuffed up the end of it. Shouldn't really be handling these they're dodgy. Oh, i know why they've done that style, but the static mode puts the most uh stress on those resistors at the beginning of it, and sometimes they just melt right through the insulation. That's not good, but anyway.

The first test we want to do is on the plug. Here. We want to see if the fuse is connected and if it's in the correct pole, so the first test is to take the fuse out. It's a 13 amp fuse.

It says whether it's a real fuse or not, let's plug it in without the fuse they lit, so the fuse isn't connected uh the earth pin has that uh plastic spacer on it, which it's not so critical in this instance, since it's really just been used to Open the the shutters for the live and neutral, but in if that plug was used in an actual earth appliance, it would not be good because it wouldn't make a connection now the fuse hold on i'm just going to crush this fuse. Let's just grab a pair of ours: let's grab a vice, i shall crush the fuse. It should be full of sand if it's a real fuse. Hrc british compliant fuse crunchy crunchy any sand.

Ah, no, there is no sound, so it's also a fake fuse, not that it really matters, because it turns out it wasn't actually connected anyway, good, that's what we want from crappy led lights from well: grey, import, ebay and amazon have done a wonderful electrical safety standards. Right, okay, next thing have they secured the little cover against being pulled off by an over-exuberant child? No, they haven't so uh. That's not good about this. Is this secured? It's usually better.

It's okay! It took a it took an adult to get that off. So here's the controller - it's got the usual little strip, uh the sort of sill mounting uh circuit board. In here i think i may have destroyed that. I'm not really that bad about it and it's got two little mosfets and a bit of circuitry just the most basic stuff, uh and uh.

It has a bridge rectifier here, the mains comes in, gets rectified to unsmooth dc and then it gets switched by these little uh thyristors and that's what flashes the leds on and off. Okay, right, let's investigate along this string and see, if there's any surprises, it's not uncommon, just to find bare wires across them, but as it is, the wire itself is extraordinarily thin. Some of it's like unbelievably thin. It must make it very hard for them to actually manufacture this stuff.

Okay, this is tied in a knot. Right, tell you what i'm just going to pause momentarily while i untie the knot. Okay, i have done some investigation, let's explore, so it turns out. There's two circuits: there's the small stars and there's the big stars.

I may have broken the controller slightly, but that's okay. We shall explore it later. Uh, the circuit with the small stars has five leds in the small star, i'll zoom down this five leds in the small star and then two in series and the top one of those has a resistor built in so because there are effectively um. Six sets of these is that right, yes times six, and this is also times six, then there are 42 leds in series, so they've got five resistors six resistors should say uh limiting the current to well we'll measure it, but it has to drop if there's 42 Leds in series roughly say three volts, each or being generous 120.

It's dropping about half the main supply voltage here in the uk and it'll be different. They'll use different arrangements in america for the 10 uh for the large stars. They've got three leds coming down the string and then they've got 10 in the star itself and one there's a resistor where i've shown the little boo boo lens. That's where the resistor is in there can.

I show you one they're, very small. They are excruciatingly small, resistors, they're, they're too small, to see that's how big they are. It's not great. They are eight watt resistors, the cheapest they could get so the construction inside the sleeves is the typical you've got the led with what they call uh concave lens.

That means that the light comes up and it spreads out sideways gives very wide viewing angle very common christmas light lens and they've got a little plastics of h beam that if this is the led viewed from the top well from the bottom. Actually, the h beam goes in like this between the connections and then they sorted the wires on and that just stops them touching together. They then put a bit of heat shrink over it and shrink it down, and that is it. That's your strain relief.

It's not strain relief. These things are usually very easy to pull apart at the end well and the others, the ones with resistors they put the resistor down in the string. Oh that's the final one. That's no good they've got the resistor in the string and it's just on one side: uh snugged into that little h, beam, plastic, h, beam and then the heat shrink put over it again, so there's actually less strain relief there on the resistor ones.

The resistors are also usually overdriven, but in this one they weren't getting too hot. They were getting to 50 degrees celsius, which is okay, that's hot, for electronics, but that's, okay, the other one, that there is one connection this it's when all the strings come to them. They go on to the common positive, which runs basically, one common positive runs to the end, and then it loops through all the lights in the way back uh. The two strings then comes back to the controller switches, the negative and because of that one.

At the end, has an extra pudding joint of three wires going up the inside a big blob of soda, and then they put another layer of heat shrink over that and, to be honest, it feels very spiky. The any spikes in the soda will potentially push through the heat shrink and any heat. If this resistor heats up too much in some sets, it will melt through the heat shrink. The controller itself is a classic little circuit.

The main supply comes in gets converted through a bridge rectifier to dc, but not smoothed. The dc feeds in this case in the uk will be plus 240 volts and it will be fully rectify, but not smooth. That's why it doesn't go up to the peak voltage and this will be for the circuit reference, zero volts, but it's actually reference to the mains. It then goes through this awful resistor, it's 120 k, resistor and it charges up this capacitor, which powers the unit and the unit obviously has some like a zener diode or something in it to actually cap the voltage.

It's just a very minimalist approach. This resistor was at 150 degrees celsius above ambient i'm guessing. The controller is universal 120, 240 and in the uk they get smoking hot inside. That will almost certainly char up after a while that resistor, i should think and may flash over.

So that provides the current limited supply to the flasher, the flash there's a little button going to the zero volt rail to actually toggle through the effects and there's also a 5.1 mega ohm resistor going from the live sampling, the mains frequency for the timing. The switching is done through between two to four little thyristors thyristors are devices that, when you trigger them a very low current, they will latch on. So that's the main advantage. They're suitable for switching high voltages and they've got a very low turn on current, which is needed here.

Given the limited supply here, and each string then, is composed of multiple resistors and then multiple leds and that's how it can flash the bars of forwards. And i shall show you how to bypass that and stop it flashing, but keep in mind the resistors will get hot in the string and also uh it's electrically dangerous anyways. So it's probably not a good idea if you've got a set of these for christmas. My apologies: if i'm scaremongering you it's not really intentional, just yeah, i don't know what to say about this bin them is what i got to say about that uh.

Here's the controller, let's measure the current going through the strings because i did notice the leds and the strings were not getting too hot, so i'm going to turn the power on with the controller open note that this is dangerous. That is now live at mains voltage. I'm going to put my meter to current and i'm going to put it to dc current, let's put it into the lower center, the higher sensitive terrain and turn it round to 20 milliamps dc, and then i'm going to pull out this little controller. Actually, i'm going to unplug that and i'm going to unbury it from the leds because it's decided to get cluttered leds.

So if i go down here, am i going to be able to brighten this picture up a little bit yeah a little bit? If i zoom down, i can show you there's the bridge right before it converts it from ac to dc. There's the button there's a very, very hot capacit resistor there charging this capacitor the little chip with a blob on it, which just the way they do these and the little sense resistor for getting the timing and then the two tiny little uh thyristors. I shall plug this in again. Note do not do this with the power on it's a it's dangaroos uh.

Only one channel is working because i've already burst it, but i think i've pulled on the leads out, i'm going to bridge across that, and it should bring on one circuit continually, it's bringing on the little stars and the current is well almost 666.. That seems a pro is 666, that's appropriate 6.6 milliamps and the current through. Presumably the big stars is five milliamps, that's not bad current. It means that resistors aren't going to get super duper smoke in the hat right here.

So, as always when you've been using, your meter switch it back from the current range over to the volts and domes range always remember to do that, don't leave it accidentally in the current range or it will go bang. So if you wanted to make these stay on the little thyristors here, have the long pin one pin going up to the little chip there, but the other two pins you can actually just bridge them out. You can do it in the back. Technically speaking, you could just take the one common positive lead and then twist the other two negative leads together that are switching the strings.

You could just basically tack it across the pads to go across that bridge, rectifier um. So what else can i say? Oh yes, so now i've had demonstrated that, let's give it the pool test, is it going to pull out easily? Yes, it is. It didn't take much if that's snagged in a branch you were putting in the tree. That's much lower pull strength and it's exposed live connections.

You may think i was using excessive force that was not excessive, worse uh there there's no strain relief in these. The wire is what i'd call single insulated: it's not compliant. It's not safe and, although it says use usable outdoors, because these have got a little heat shrink sleeve, but they're open at this end, the water does wake up they corrode inside. But more importantly, they form an electrical path and you can actually get a shock off the back of these, so i wouldn't handle them outdoors in the way i wouldn't handle them at all.

Full stop they're terrible! So, let's, let's sum this up: um smoking, hot resistors in the controller that is very easy to pull open even with child strength, uh plug that has a fake fuse uh, but the fuse isn't connected anyway, and it's got a sleeve pin. So there's like three safety violations in that already that resistor get gets absolutely smoking hot in there there's no strain relief. The wire is not insulated to thick enough standard for mains voltage. In short, what i'm saying here is: if you've got some of these biomes, you could unclip these little stars and things and use them as low voltage lights.

If you want to salvage them, but really don't buy the cheap grey import lights from ebay. If you're going to buy christmas lights, get them from a local supplier like say, for instance, asd and walmart, to use just examples of what i mean by a prominent brand that has to protect their reputation, preferably the ones if you're using them outdoor. That of the little plug-in level is transformer that way nobody's going to get electric shock and they're not going to go on fire, and that includes uh shocks to pets as well as kids and and adults. So um yeah they're not great but they're, they're still on sale.

I'm really surprised they're still in sale. Ebay clearly doesn't give a toss.