Two different USB rechargeable hand heaters. This one also doubles up as a power bank and I've featured one. very similar to this before and it's quite odd for having if you click it three times a vibrator in it, but it's not really good for vibrating me. It makes the noise like a like you've you know.

basically got a phone call coming in, but it doesn't really vibrate strongly. It also has for a double click. it's got a little light in the front which is quite nice. It's also claims for you to ten thousand milliamp hour We shall see.

I Should check that out in the future I shall turn this off It's notable that when you turn this one on into heater mode by long pressing that, it gives three different temperature settings. It's extraordinary how fast it heats up. you can feel the heat almost instantly. This one lasts so.

uh, this one has a appearance of being styled on Disney's Frozen Probably slight value should cop right there and you turn it on. It claims to have a 5 000 milliamp hour cell. doesn't feel like it at all and it's uh, it takes ages to heat up. It also offers you two color modes: monochromatic or uh, you can have color changing, none of which actually makes the display light up at all.

It's kind of like very weird, but that's okay. Uh, long press turns off. Let's take this one apart. I Shall feature this one in a future video.

We'll see if it's any different from uh, the last one which was quite interesting. It was okay. so this one that there's no screws. So I'm guessing I'm going to have to spudger this off.

It does. spudger off, That's good and reveals the heater pad. It's um, what's the name for that Captain tape type. It's that malar tape.

It's sort of like the heating element zigzag. Let's take a closer look. It's also got what looks like an 18650, which pretty much means it's not 5000 milliamp hour because they don't do 5000 milliamp hour. 18 650 is the best of my knowledge.

It's also got tiny screws. Do I have a screwdrivers even gonna fit that? I may have to I may have to have a hunt for a screwdriver that's going to fit that? I shall of a hunt? Uh. Also, it's got a couple of wires going to, presumably a thermistor. Um, are they going through? They are going through one of the same holes that the hold of the case clips into.

That's a bit messy, right? Tell you what. I'm just going to look for a screwdriver because uh, I appear to have misplaced the one of that size. One moment please. I have located the screwdriver.

Uh, features on the 5000 milliamp hour rating. It says it. Heats both sides it does not. It says it doesn't explode.

That's reassuring and it's perfect for heating, uh, various parts of your body. It was a bit strange to figure where did that. So what am I expecting I'm expecting a soccer board with a charging chip, a button possibly a tri-color LED Or if they use separate LEDs and a little open chip perhaps and a transistor like an E2shb for powering that heating element because it doesn't get very hot, just going to come apart. Yes, it is.

Well, oh, it plugs together. That's quite nice. We can unplug it then, right? Tell you what before I unplug it the therm. The thermistor doesn't unplug.

Um, right. Tell you what. The white connector goes to the heating element. The red connector goes to the Lithium cell of unknown capacity.

It feels warmish. I think it was giving off more heat in the heating element. Uh, right. Tell you what.

Let's take this big sponge off. Oh, is this sponge gonna come off? I think I may have to apply isopropanol to this. see if I can liberate its adhesive and get the thermistor to separate. Is there going to be a little beads? thermistor? It is going to be a little bit thermistor.

I Bet that's a 10K thermistor. They're very, very common. Let's get the meter and let's try that. Although having said that, it may be skewed by the other components in the vicinity.

Well, I'm seeing the little charge chip and I'm also seeing what looks like a little, uh, five per microcontroller. Um, nothing. right? Tell you what it might be 100K Thermistor: It's a 100K thermistor. Okay, uh.

when I say 100K thermistor? it's reading 93k. The 100K is 100k at typical room temperature and this is a 10K right? Does this just pop off? Is there a screw? I don't immediately see a screw I'm a bit notorious for just ripping things off and then finding screws afterwards. I'm not finding anything. Oh, it's popped off.

Oh, there is a little, uh, eight pin chip on the back. Maybe that's uh, oh right? What is that? Then right? Tell you what. There's only one way to find out. I've snapped all the plastic pins off I have been destructive.

This is not surprising at all. Is it big destructive? Clive Right table. I'll take a picture of this and we can explore it one moment. please.

Reverse engineering is complete. Let's explore it. and I Have to say the circuit board isn't too bad. It's a lot more sophisticated than I Was thinking it was going to be very neat indeed.

The heater is also quite interesting. It passes 1.25 amps at 4.2 volts and 900 milliamps at 3 volts. so fairly capable. Uh, the case is okay, even if it does just heat on one side.

That's okay. Then the accounts Department got involved and they put in a 600 milliamp hour Lithium cell, which is roughly the same capacity as a typical disposable vapor device. Which means that the whole product because you can easily open it to change the battery without. Well, we could.

But if you have one of these, yes, you could upgrade it. but the whole product is just rendered useless by their accounts. Department Putting in a tiny cell to save the wheat pennies? Not to worry, let's explore the circuit board because the circuit board is Worthy I shall Zoom down in this. So what do we have? We have the incoming Supply on a USBC connector.

There are no identification resistors in this. Usually there are two resistors and it wouldn't have added much the cost at all, but they didn't add them so it's a dumb USB connection point And it means that if you plug this into smart devices then they may not even acknowledge that it's there and they won't start charging it. If you do have products that are in the same situation and there are lots of them and it refuses to take a charge off your favorite USB power supply that came with your latest phone, then just use it with an old dumb charger and it will charge usually. So let's start off.

We start off with the charge control chip. the Lth7 set for about 500 milliamps which kind of fits with this. They could have set up for one amp and you could have used a bigger Lithium cell. Maybe they just planned this in the beginning.

there's a red LED for that. Uh, there's the Thermistor connections which we'll cover. On the other side there is a all-in-one Dw01 and Mosfet on the one package. it's the Badger protection device to stop it being over discharged.

it will basically cut off either an overcharger over discharge. There is a mysterious R1 position. The only reason I can think for this position is to bypass the protection. So while the accountants missed a check there, they could have just made it cheaper and just made it a completely disposable product.

Two connectors, one of the battery, one for the heater. Anything else worth mentioning? This site? No. Okay, let's go on to the other side. This is where all the magic happens.

I Mean that's a magical site and it's so incense. The uh. the battery charging and protection is actually very good. Shame About the product: There's a classic little eight pin ubiquitous microcontroller here, and it has an interesting feature.

It's got an enable pin that does two things: it enables the thermistor circuitry, and it also enables this mosfet here, which turns on the LED because it turns on out. The LED is an RGB LED light ws2812b That's what I've written here, but it's not exactly that style. But it's got basically positive, negative, and data. And we've got another mosfet here.

Uh, Three, Four, Zero, Zero. This is flipped by the way so it kind of matches the other image and it switches the heater. Um, anything else worth mentioning here? Nope. Let's go straight to that schematic and explore it.

Here is the schematic: I'll go a little bit closer because well, some of you have small screens and it makes it so much easier to read if I Zim up in it. Here is the battle implemented: USB port come in uh, decoupling capacitor across that and then a couple of wrist resistors creating a divider. Now, these are tiny resistors they've used so I kind of measured them in circuit. Don't think it was accurate.

roughly 30 cage. Um, it's hard to without having numbers on them or take them out of socket. It's hard to actually tell the value, but they have a tap off point that goes over to the processor and simply tells it when USB is plugged in. If you plug USB in, it turns the rest the circuitry off so it isn't trying to heat at the same time as it's trying to charge because with the high discharge current, it means it would not be able to achieve that.

It has an Lth-7 Classic charge chip with the 1K resistor and a red LED to show when it's in a charging state. It has a programming resistor of 2K for about 500 milliamps decoupling capacitor. there's the Lithium cell. That measurable lithium cell with a little resistor capacitor Network across it with a top-off point going to the protection chip which I have abbreviated I haven't really abbreviated I've shown everything there is the chip May Well have a high number of pins, but it only effectively uses three connections.

The microcontroller has its decoupled Supply 10 Ohm resistor video capacitor that just isolates it from any switching happening in the lanes and gives it a fairly stable Supply It's got a button input that just pulls to the zero volt rail. Um, and then it's got an interesting output. This is the Enable I'll put a little Dash a little stroke above it there because it's the enable low. When the unit is turned on, it turns on two things.

by putting this law, it enables the thermistor. Network because the thermistor network is based on a drive measuring circuit. Again, got weird results 100K resistor and a definitely 100K thermistor. Usually when they implement this, they do match the value of the thermistor and it means that as the temperature varies the voltage, it acts like the potential divider.

It will vary up and down between near the supply Rail and zero volts depending on the temperature. There's a little capacitor there just to provide smoothing and stability. This also turns on this mosfet. There's a 1K resistant Turn on.

There's a 10K pool up resistor because it's a P-channel mosfet P Channel B Chan and this is n Chan and when it turns that on by pulling it to the zero volt rail, it enables the LED This is because these LEDs the smart LEDs do have a crescent current draw because they've got active circuitry running all the time in them. So when this unit's turned off, it actually turns off the RGB LED too. The data to the RGB LED comes via a 100 ohm resistor. Reasonable enough, and after that, we've just got the other mosfet and inch on a mosfet which is turned on Via this one key resistor.

It's got a 10 key resistor to keep it pulled down to the zero volt reel for stability and it turns on the heater and that is it. It's quite a nice circuit. It's quite a complex little circuit, and they've jammed it in into a very interesting shaped circuit board. It's nice because of things like this extra protection and this is also interesting because it's a good example of how you can save on losses while the unit is asleep by turning off uh, external circuitry.

so that is it. A nice circuit. Lovely circuit board. Stranger, they used to be copper wires I guess they've got low thermal Mass Also, cheap, nice enough flow heater could be useful and uh, hobbled completely by this crappy Lithium cell.

but then that's just ultimately what happens. So there we have it. the frozen-ish Style by the image on it. Uh, little hand heater that is a great unit.

Hobbled by one bad manufacturing decision made by the Accounting department. What a surprise!.