This video is about a set of outdoor solar lights with a really nice solar panel. It was recommended by a friend who said uh I've got a set of these. You really want to see the solar panel. It's really good.

It fills up the whole area and it does I think it's the laminated plastic uh type of a silicon s panel. However, I tried ordering a set from an eBay seller and because I'm currently on the aisle of man they just basically canceled order. they wouldn't send it. so the only person I could find that was like to send it by standard mail.

uh was somebody that looked as though they were selling sort of customer returns. So I ordered one and when it arrived uh it turned out that the lights didn't work and if I turn this on. These have had an absolutely terrible incident because if I take a working lamp and screw it in, it lights up every single other light is dead and it was pretty clear that they were because if you you look through them, the filaments uh inside the little LED filaments all have black dots down. The only way I can think of this happening on a low voltage set is if someone has plugged this standard connector uh into an ex.

They've tried to use it to extend a 240 volt set which would have been very violent and literally blowing every lamp in the process but then to addult to injury. They then got the spare lamp and they plugged that in as well so every single lamp is dead. However, the seller did the noble thing and they sent me another set. So in a way, that's a win because the other set does work.

and now I've got two of these lovely solar panels and we can explore one. Let's open it up. So I see, there's 1, 2, 3, 4, 5, 6, 78 uh screws in here little tiny ones. so I'll whip them out and we can get inside.

It's worth mentioning that, uh, my preference for solar panels. The ideal ones would be the ones that were on glass. My second preference is the ones that are laid onto fiberglass like you'd get the um, what's the best way to describe that I'm looking around and see if I can find one and oh, there's one. These ones.

You know, the ones that are on a fiberg, glassy type circuit board. CU It's got a good, uh, rigidity and it protects the cells, especially against thermal expansion contraction cuz it's got a similar characteristic. Um, that, and, uh, morphous. the brown sort of panels.

They're quite good. This is where, yes, a cordless driver the high speeed one to zip these screws out would have been a benefit. That's all right, it says down. Downside Install.

Let's see what we got in here. We've got one screw not quite out yet. the solar panel over got two 18650s. Lots of uh, hot milk glue around where the cable goes out.

Uh, these are 1,800 mlia cells. at least that's what's printed on them. It doesn't necessarily means that what it is. And there's the circuit board.

So you know what happens now. I'm going to take the circuit board out I'll take a picture of a reverse engineering and we can explore the circuitry one moment. Please, Reverse engineering is complete. Let's explore this circuit board.

It's quite interesting. On one side we have the USB micro USB input connector. We've got a moment action clicky button and a click on click off button. On the other side we have a lot more.

We have a red green LED I'll Zoom down this because you know what that? this. There's a lot. There's a lot to take in in this circuit board. Have a red green LED controlled from a 4057 which is a standard charge chip.

so there's a USB connector. It's providing power to the 405 57 which then charges the cell when you're not. well, you can probably charge it with solar and this it's going to charge it around about 1 amp. The cell protection is a D3d uh with support components.

Down here there is a universal mystery microcontroller and a very interesting chip 7136 which is a linear current regulator that you might find normally in your LED ceiling lights, but in this instance they've got a variant that is a regulating the current through the LEDs courtesy of this auxiliary mosfet and then a mosfet being controlled by the microcontroller to switch the actual LEDs on and off and make them Flash and do things Uh, there's a current sense resistor down there for that current regulation circuit uh, a couple of resistors for the LEDs uh, and a couple of resistors here for uh, pretty a slight load in the solar panel and also providing a slight signal to the microcontroller to uh sense dusk when the voltage in the S panel drops down makes it don't sound so easy. It took a long time to reverse engineer, but here is the schematic and I'll zoom in even closer for this one. This is one of these things that you know. There was so much time spent finding mystery chips on the internet and getting data sheets for them that, uh, It kind of.

It's odd to actually just give a quick summary. So here's a Usbn: It's using the proper circuitry. here. it's using A25 Ohm resistor and a decoupling Capac just to provide a stable Supply into the 4057.

Most Uh circuits seem to miss this resistor, but it is shown the data sheet. There is also a very odd 300K resistor going from the USB input over to the chip to enable it that's not normally used in other circuits. Sometimes it just tie. If there is even an enable pin, they'll just tie it to the positive input.

There's the programming resistor 1.1k which is round about uh 1 amp usually for that I think and then we got two 1K resistors for the two. L is red and green which go to the Uh chips so it can signal if it's charging or it's completed charging little. DEC discovering capacitor to the Z volt rail. A little block there underneath the capacitor means it's tied to the Zvt rail down here.

Um, there's the solar panel. Oh uh, let's go to the Lithium cell first. So the Lithium cell is here and it has a D3d which is an all-in-one mosfet and Uh protection circuit and it measures the voltage across the Lithium cell via this little decoupling Network just to provide a stable Uh voltage 100 ohm usually 100 Nano here that provides feedback. The 1K resistor is a reference resistor.

It can detect when there's very high current flowing and uh, basically short circuit and over uh, charge and discharge protection in terms of current, but the Uh this detects when the voltage gone too high or too low. The microcontroller I would expect to turn off prematurely, but as this is the solar panel can theoretically charge that up until the D3d kicks in, which is a bit above the normal charging voltage of a Lithium cell around about 4.25 volts. Usually, the solar panel charges the Lithium cell as an alternative to the USB via this shot key Diod and it just goes straight to it. The current limiting is purely what the solar panel can deliver um, the output of the solar panel is monitored by the microcontroller here by a 10K resistor.

So it's merely looking at the voltage on the solar panel. It might even just be looking at a logic level. When it tacks, it's gone below that level. it will uh, tell it basically that it's Dusk and to turn the lights on.

It's worth mentioning that these chips tend to have protection DS in. so this has to be quite a high value of resistor. Otherwise, the Uh chip could this Uh solar panel could effectively via that resistor feed the positive rail. Although there's not going to be much load on the positive rail cuz there's just a couple of chips on it.

There is a switch between the Lithium cell and the LED and control circuitry. Technically speaking, the solar panel can kind of keep that awake by trickling current in there. That is quite odd. I Wonder if it will keep triggering it when it does that? There's a 100K resistor across the solar panel, though, to provide a slight load just to make sure that when it gets dark, the voltage across it goes low enough that this Uh microcontroller can sense that the microcontroller has very few pins used.

It's got the power pins. Then it's got three pins. One is a switch input just for a clicky switch to actually change the settings, one is the dusk sensing input, and the other drives a mosfet. The when it turns the mosfet on, there's a 100K pull down resistor to keep the mosfet off normally then a 10K resistor to actually turn it on, but the current can't just flow straight through the LEDs and through that mosfet.

This is where most circuits would just have resistor and series of the LED but in this case they've used this D Well, it's not a D I Think it may actually say D 1 7136. That was quite hard to decipher because there's a very similar chip. Um, very similar chip that is just a simple 3.6 volt regulator which wouldn't make a lot of sense given that. uh, the half voltage of this cells 3.6 volts.

But it turns out uh, there's an equivalent QX 7136 which is a data sheet and it's a LED current regulator that can either limit the current through the LEDs directly on its LED pin cuz it has a built-in mosfet or you can use an external mosfet. and they've used an external mosfet. I Wonder why they didn't use the one that's built into and they actually chose to use an external one instead. But there's a current sense resistor and it's looking for a voltage across that resistor to measure the current of about 05 volts.

50 molts. Let me show, there's the that circuitry. It's really simple. It's a opamp with a 50 molt reference and then the current sense resistor simply starts turning in that internal mosfet off or drives the external mosfet off When uh, it starts reaching the required current and the voltage across that rises to that level.

There is another page here and it's the odd uh, Dw3, Which is there's the short circuit protection resistor. Let me zoom out for this because that is quite big. Uh, you can find the data sheet for this online, but there is the network across the Lithium cell that goes via the 100 Oh resistor and the Uh 100 Nanard capacitor um and then goes to the sense input um, and it switches. It's got two mosfets built in, but strangely it uh, it has the control outputs going to the mosfets actually leaving the chip and going back in just for versatility.

Quite a complex number of integrated circuits in this, but the main thing is that this module, which is always active when it's turned on. This connection here goes up to the positive Ra. Uh, this circuit will continuously be wanting to regulate the current uh based on the voltage across this resistor here. So when this transistor turns on, uh, the current through the LEDs will be regulated now.

I Did discover I Dug out a set of 240 volt lights. Hold on. Let me get the original ones. These are the dead ones that someone has had a terrible incident with and they've got little black dots inside.

It's worth mentioning that uh, worth mentioning that LEDs Don't fail the buying. These are failed in a very controlled manner I'm assuming they may have been put across the mains. Hold on. Where is the set of Lights This is a real set of 240 volt lights and it's just basically provides 240 volt C across these.

Where is the connector at the end of this? the extension connector? There it is. This might explain how this could happen. so this would be 240 volts, this string would be 3 volts and they are completely Uh compatible. You can plug them directly in, straight into 240 volts.

I Reckon that someone may have bought these off Amazon or something like that cuz this whole thing is a hint of Amazon returns to it I reckon they may have bought them off Amazon as a cheap extension to their existing lights, plugged it in Blowing them up and then returned them and said these don't work Uh, but that's okay. that uh turned out to our benefit because we got to reverse engineer stuff and work out what had happened. So that is it. It's an interesting little circuit.

SL Avalanche Happing the background uh and quite complex I mean the fact it uses an unusual charge chip. it uses the unusual protection chip unusual variant and then it's got that unusual use of the linear current regulator makes it quite a complex circuit. and there are one chip solutions for this. but they've used uh this approach because they just wanted to deal with higher currents and give themselves better options.

It let them it. Let them um charge the bigger cells which I'm I'm going to test I'll put a note in the description down below of the capacity of those cells once I tested them but Um by using this Uh arrangement of components that let them specify currents through the LEDs that let them specify by charging currents that just let them tune things to their own Uh desires. But there we have it. a very interesting Set of Lights and well worth taking apart.