Like it or not, christmas is approaching, and since all the christmas lighting has started appearing on the shelves at places like jack stores and ramsey, i thought i'd buy some now. I think this is this year's stock. It could be left over from last year, but the isle of man loves its christmas lights because the general environment is pretty dark, so they look fantastic in the gardens, so they always sell out a christmas light. So i think this is new stock.

Let's take a look and you might think well, you've featured christmas lights before. Yes, i have, but i like to see how things evolve. I like to see how the colors and phosphors evolve and i like to see how the control systems evolve so restart you're. Getting a fairly nice little battery pack now i'm wondering they've got smaller sets.

I wonder if they contain the same battery packets, it's got a proper seal and it seems waterproof, um, okay, let's stick some batteries in and then we shall whip this cover off and see. If the circuitry is changed, if it's a still, what was it last year, microcontroller uh an h bridge driver right, i won't bother closing it. I will close it. I shall close it down and click it.

Okay, that probably made a really loud pop in the microphone. Click yeah, it's the usual polarity inverting one. I'm going to unravel these and see how they're wired it's just a parallel circuit. So this is the type that has alternate polarity leds and it swaps the polarity going out to the output.

So if you put it through to the two three five, six, seven, eight, oh new patterns, if you put it to the static setting, it's not actually static. I don't know. If it's going to show the camera, you can see a slight shimmer, it's actually alternating the polarity to the two channels to make them stay on. This is quite annoying because otherwise it'd be really nice.

Just to you know, use these with say a usb power supply, but if you do that only every second led will light that could be useful. It means you could choose a string, that's either just red and yellow or just green and blue. So, let's see what the circuitry is like, this also has the ubiquitous timer, that's in it so combination, which is all the facts in wave sequential, which is only two channels, so not that exciting, slow glow which is terrible, chasing flash. It's all right, it's very classic effect, slow fade.

Also a bit uh twinkle flash, that's the kind of new one and steady on right, let's open it, so i shall put the batteries out and we'll see. What's inside, i can remember the first ones these came out. They were terrible, they uh tried to use the existing higher voltage lights and used a little boost circuit and uh. It resulted in very short battery life and instability of circuitry.

I shall zoom down this actually i'll bring it up here and i shall zoom in it's way out of focus and then i shall focus on that. Boop uh. What am i seeing? Not a lot? I don't see i'm gon na guess this is a single-sided circuit board, this chip, capacitor, probably across supply rails, button, um and probably a crystal for the accurate timing right taiwan, i'm going to whip this circuit board out and we'll take a closer look at it. One moment please: okay, let's explore.

I shall zoom up a little bit uh, not an awful lot to see the back of the circuit board. Where is the circuit board? It's so small. I've lost it. It's just a plain circuit board with the crystal in the back.

Probably 32.768 kilohertz um there is a chip now, while this is a standard, microcontroller and they're abusing two of the output pins, because when an output pin is high, it was positive and when it's load was negative, it's possible. They could be abusing that, but uh to actually drive the leds directly, but i think this chip probably has a buffered output in those pins. I'm not sure it is. It has a very standard sort of power pin out here, but we have the negative communion and it goes to capacitor.

Positive crayon goes to a capacitor and they go to the supply rails of the chip. There is a button that pulls a one-pin to ground and there is that crystal in the back 32.768 kilohertz and then there's the two outputs to the leds and that's it, and they have added the provision here for a resistor to go into series to limit the Current through the leds, but they've just bridged that out with copper at the back of that, it's just a sort of design option that they've blocked out right. So the schematic it's not going to be very complicated. The schematic is going to look like this there's the plus fire 4.5 volt rail of the batteries which will drop gradually as the discharge here are the batteries three batteries in series double a's.

We have the little capacitor the de-covering capacitor, which goes straight across supply rails. Just to provide stability to the microcontroller, and then we have the microcontroller mysterious microcontroller no number could it be a paduk and it has a connection to the positive rail. It goes up a connect connection to the negative rail and then the outputs to the leds. Leds.

Keep your mind that some of them are in this polarity and some of them are in that polarity, so they can alternate as the uh it switches. Apart to the output, the leds alternate or for static it just uh alternates very quickly between them. So it gives that persistence of vision. It looks like they'll look continually.

There is the button which uh is going from the chip to the zero vote. Rail. That means internally. The chip, technically speaking, has a little pull-up resistor inside going to the positive rail and when you push that button, it pulls it to zero volts and that changes the logic state to zero on that input.

And then it knows that something has happened. And finally, it has the crystal which looks a bit like this in a schematic um, that is it it's one of the most simplest designs. I've come across yet now. Let me uh get the kink calculator and show you is this going to work hold on on? Let's try this 32 768, which is the frequency of the crystal divided by two equals sixteen thousand three or ninety four eight thousand one hundred ninety two: this is binary.

Four thousand. Ninety six, two thousand forty, eight one thousand twenty four five hundred twelve 256. 128. 64.

32, 16, 8, 4, 2 and 1, so that 32 768 actually divides down nicely in binary uh to a one hertz time base and uh in this circuitry. They will be uh dividing that again by 60 c, to get a one minute time base, then by 60. Again, to get a one hour time base and then they'll be dividing it by six to get that six hour cycle six hours on 18 hours off and then they'll, probably just counting a two-bit binary counter, because that will be when it's at zero. That will be the six hours on and then the all the other states will be off it's very.

It's almost boring. Quite frankly, it's just so simple they've, stripped it to the bare minimum, but that is how it is so. Uh yeah the leds, because they've got them all in parallel to match the intensities they have used the well. I can actually power this up.

This is where i blow all the leds up. I shall try not to blow the leds up with the power supply, so i shall find the two led connections there. They are, oh, that was a residual charging capacitor that made them flash and i shall gradually crank the voltage up, but they have used phosphor coated, leds, they're, all blue chips, the only ones that are raw blue chips are the blue leds. The green is phosphor and the red and the yellow is phosphor, so at three volts is that roughly than tends to they were before that's about 200 milliamps, maybe that's close to what they were before about 100 milliamps.

So i'm guessing the current will be limited by the output of that chip. And when i swap the polarity here, the green and blue are lighting one polarity and when i swap over to other priority, the red and yellows will light and there they are at the other side, which makes these lights just that little bit harder to try. I'm going to have to i'm going to have to resolve a little circuit that just simply does basically, i have h bridge drive with self feedback, so you can actually drive string of these without having their dedicated controller, because it's annoying when it's got this built-in features. But there we go, that is the current state of play with the christmas lights, i have to say i'm getting a slight deja vu.

It makes me wonder if i've taken a very similar one apart, but um that's what this one is and to be honest at that cost, it's actually worth getting just for things like the case, because that's a fairly good little waterproof case. Of course i've not actually tested it, but it looks pretty robust. It really snugs that seal down you click it shut, but there we go uh. This year's batch of lights, kind of which brand that was which brand is it.

Does it say no, it's got tons of text on it, self-import agencies, but the box looks like this and they do various multiples of these uh sets. They could do the sort of higher number sets, which i think above a certain level they switch to using the plug-in power supply, but below that 96. I think it's 48 or something like that. They do the battery operated ones.

But it's neat enough: it's a nice enough! Little set of lights!.