# Solar power for \$1! – Dollar General calculator teardown

For some reason my video of fake solar calculators It is having new success on YouTube. So when I was recently shopping at Dollar General I was inspired to buy this calculator It's a one dollar calculator in a sachet. I don't need another calculator, definitely not so cheap, but I was interested in understanding: claims to be dual current source, and here is what appears to be a solar panel therefore, even if a large part of these fake solar calculators they do not specify anything about the solar panel, even if they seem to have one, this clearly specifies to be dual current source.

So I absolutely have to open it to understand if it has a real solar panel. I noticed it also says: "The batteries in this device they are not replaceable; do not try to remove the batteries ". Even if it looks like it has a chance to replace them easily, so I don't know what all this means. (I breathe) Here is the instruction leaflet. So let's open it. Here it is. Here is the instruction leaflet. And again, even though it says the battery is not replaceable, clearly specify what type of battery to use.

Obviously it is "Made in China". And it works flawlessly. Obviously it will have the typical approximation errors due the limited number of digits it can display. So if I take the square root of 2 times the square root of 2, it should obviously be 2. Not exactly. This happens because it has no additional digits: all that is on the screen is that which is saved in memory. Same thing if you divide 1 by 9, multiplied by 9, which should be 1, And as you can see it is 0.9 per repeat. For the rest, it is the typical four-function calculator. (I breathe) And here is the doubtful solar panel, which could be real or fake. So first let's see what battery is in there.

There is an "off" button, which is not often seen in solar panel calculators because what would be the need to turn it off if it is powered by light. Ok. Well, this looks like a replaceable battery. So I can't understand why they specify that the battery in this device is not replaceable, do not try to remove the batteries. Ok, I think I understand what they mean: it appears to be removable, but it appears to be recessed under the plastic housing. So it will probably be very difficult replace the battery without disassembling the entire calculator. Although they do provide a door to get there. But let's start taking it apart. And just a brief mention about Dollar General.

I watched a video from Retail Archeologies on Dollar General: showed how the supermarket was messy and disorganized, and how they sold expired food. It just wasn't a good experience at that supermarket. Well the supermarket I went to recently changed sign from Walgreens to Dollar General, then is a newer store, and I haven't seen any of that in this supermarket: he was well stocked and organized; I have not seen any expired food, even though I didn't pay attention to everything. But I still have to point out that when it was a Walgreens, it had nice incandescent lights, and for some reason, when they converted it to a Dollar General, they made them all disappear in favor of some very soft lights cold white led, who made it shopping very depressing, in that it was really dark in there. I realize they were probably trying to save on the electricity bill, but they could at least put some extra light in there, so as to make it easier to see what's on the counters. Ok, I try to …

… take this calculator apart without destroying it. Ok, here it is with all the screws removed. Haha I like that they used cardboard inside the calculator. Never seen such a thing. but there is a real solar panel in here, or at least it is connected. So… … it seems they weren't lying when they specified that it is dual-fueled. Here is the battery, and the solar panel. So, build quality: nothing worse than that to other calculators which I disassembled in the previous video. So: Dollar General: Good for creating a dual-power calculator that is actually dual-powered. I just think you could have used a better material in here compared to a sheet of cardboard.

I have now removed the battery, so it won't skew my results. If I measure the voltage that is generated by that solar panel … … now it's right above 1 volt, only by the light it is taking. If I close it bringing it close to the table, you can see it drops down to … … 0.3 volts. Bringing it back to … … therefore expose to more light … almost reaches 1.5 volts. So that solar panel is definitely working. And last time I had several people saying that the solar panels do not work with the LEDs; Here I have the same little thing with LEDs … …And… … when turned off we have more or less … … 0.7 volts; if I turn it on …

… we receive more than 2 volts. Hence the led light it sure is recovered from the solar panel, and converted into electricity. Again, when turned off we get to about 0.7 volts … … and turning it on … … now it's more than 2 volts. So… … at least as far as this specific case is concerned the solar panel works with a led. And now, with the battery still removed, it can be seen which can be turned on with only the solar panel. When I put my finger on the solar panel, the screen turns off. Even if it goes out completely, if you bring back the light fast enough, keeps the memory. See how long it takes to clear that memory. There is still. It is impressive. Even completely covering the panel with my finger. Does it have some kind of non-volatile memory in there? Ok, now I'll cover it for about 30 seconds.

MUSIC Still there! We were more or less at 20 seconds. So I'll cover it and I'll be back in 2 minutes to see if that number will still be seen on the screen. Okay, it's been about 10 minutes let's see if that number is still on the screen when I remove this shell. No. So… … sooner or later the memory is lost if you remove the power but it still lasts a long time. So I don't know if the microcontroller inside goes to standby when it doesn't have enough current to run. Because it certainly lasts a lot longer than any other solar panel calculator I have owned in the past. Here it is mounted again. It still works fine. They also had a \$ 2 version of this calculator next to the counter, a little bigger, with better frets, but probably the same at the hardware level.

Because this one has those cheap rubber buttons which do not have a good feeling to the touch. But, for a dollar, I certainly can't complain. And they're not lying! When they say it's dual-fueled: it has a battery, and a solar panel. The only thing missing and that I would like to be there is a key to change the sign. Since, to enter a negative number, you have to press: minus 8; the same, and then you see minus 8.

So she misses a key to change the sign, but still, for a dollar, quite well!.