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foone Sep 3
Replying to @Foone
Well if we look opposite the paper we can see there's three little holes here, and there's something inside. We need to get this plastic shroud off!
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foone Sep 3
Replying to @Foone
But first, a battery! It's a CR1616 3V button cell. Makes sense. That's basically a cheaper smaller version of the more common CR2032, and this thing doesn't need a ton of battery life, it's a one-use device.
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foone Sep 3
Replying to @Foone
BTW, it turns out under where the wick goes is two little connectors. This isn't a test, it's just a power switch. When the wick gets wet, it starts conducting electricity, and this device turns on.
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foone Sep 3
Replying to @Foone
So inside the plastic, there's the 3 holes and a sort of 45-degree-angle ramp that had some shiny metal on it (that unfortunately fell out before I could take a picture)
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foone Sep 3
Replying to @Foone
That sits on top of this. You know what this is? This is three LEDs and two photosensors.
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foone Sep 3
Replying to @Foone
and it turns out that the LEDs do the edge one, then the center, then it does it in the opposite direction. It then measures the light hitting the two sensors while it does that.
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foone Sep 3
Replying to @Foone
and why does it do that? so it can detect the lines on the paper! In other words, the whole point of the digital part, the battery, IC, LEDs, and photodiodes... is to read the lines and tell you "PREGNANT" and "NOT PREGNANT" instead of "||" or "|+"
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foone Sep 3
Replying to @Foone
(that above GIF is what happens when I glitch it into a test mode)
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foone Sep 3
Replying to @Foone
So, what else? Well, there's that IC... It's a Holtek HT48C06!
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foone Sep 3
Replying to @Foone
That's an 8-bit microcontroller. 64 bytes of RAM, 1024 words of ROM, 13 GPIO pins, running at either 4mhz or 8mhz. Given that they're only doing a 3v battery here and I don't see any voltage conversion circuitry, I think it's running at 4mhz.
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foone
It's a surprisingly complicated chip. You might think it's very limited because it's only got 64 bytes of ram, but it's actually using a pipelined architecture to operate at 1 instruction per cycle, giving it quite good performance for a 4mhz CPU.
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foone Sep 3
Replying to @Foone
This thing is probably faster at number crunching and basic I/O than the CPU used in the original IBM PC, and this one is in something you pee on and throw away.
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foone Sep 3
Replying to @Foone
Sadly, the "C" in the HT48C06 means this is the mask ROM version, so there's no reprogramming this chip to run other programs. We can't run Doom on this pregnancy tester, I'm sorry.
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foone Sep 3
Replying to @Foone
It also doesn't look like you can pull the ROM off the chip, at least without their proprietary online-activation-required programmer (and possibly not even then), so unless someone wants to decap this chip and read out the bits from the silicon, we can't put it in MAME either.
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foone Sep 3
Replying to @Foone
Here's the post that I was referencing:
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foone Sep 3
Replying to @Foone
Mine's a different brand and has some minor internal differences, but it looks to be basically the same.
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foone Sep 3
Replying to @Foone
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foone Sep 3
Replying to @Foone
The strips inside are probably the kind that show 0-2 lines. I may have to try printing that on some paper and seeing if that'll make the device tell me I'm pregnant or not pregnant.
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foone Sep 3
Replying to @Foone
Currently if I power it on, after doing the above light pattern, it then settles into showing me the "READ THE MANUAL, IDIOT" symbol.
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foone Sep 3
Replying to @Foone
WAITING... it better not make me wait 9 months, because while that would technically determine if I'm pregnant or not, it certainly isn't worth the money.
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foone Sep 3
Replying to @Foone
There's also a hole on the grabby end of the tester, but you're not supposed to put anything any here, apparently. I think it's just here so they can wedge a bit of plastic in here before final distribution, which'd keep the battery from making contact and potentially draining
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foone Sep 3
Replying to @Foone
also am I the only one who sees the USS Discovery from 2001?
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foone Sep 3
Replying to @Foone
They're both rebooting right now. They take a surprisingly long amount of time to boot, but it's the only way to get them out of the "READ THE MANUAL IDIOT" mode.
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foone Sep 3
Replying to @Foone
Nope, still get a MANUAL sign. I'm just not sure how these indicator strips are supposed to look, so maybe I'm putting marks in the wrong places or maybe they're too dark? I used a sharpie because it's what I had on hand.
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foone Sep 3
Replying to @Foone
but yeah, as for "WHY DOES THIS EXIST" when it adds basically nothing over the manual version that just shows you lines? It's a scam, basically. Computers are cheap now. People are buying the digital one thinking it's the more accurate fancy model, but it's the same.
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foone Sep 3
Replying to @Foone
in fact, if anything, it's LESS accurate. The batteries can't die in the manual model with the lines, and if your indicator paper doesn't light up a very bright line, your human eyes are probably more sensitive than the photodiodes in this thing.
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foone Sep 3
Replying to @Foone
And it's way more expensive. The one time use manual version, as a generic? 88 cents, vs 7$ for 2 digital ones.
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foone Sep 3
Replying to @Foone
And that's actually one of the more expensive test strips. Depending on how many you buy at once, you can get the generic strip versions for as cheap as 20 cents each.
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foone Sep 3
Replying to @Foone
SO YEAH, they're basically making money by misleading customers into thinking the digital model is better at 3.50$/test when it's just the 0.20$/test strips plus a dollar or two of electronics to read it for you
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foone Sep 3
Replying to @Foone
I dunked one in water (PLAIN WATER! I DIDN'T PEE ON IT, I PROMISE) and this is how it looks after about 5 minutes. A little more transparent, and with a single blue line.
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foone Sep 3
Replying to @Foone
BTW, to answer a suggestion no one has made yet: Yes, I could replace the microcontroller with an alternative one that CAN run doom, but: 1. it has to run on 3v, which is tricky 2. it has no inputs but "pee on it" 3. the LCD can only show "pregnant","not","manual","wait"
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foone Sep 3
Replying to @Foone
I should mod this into a flash drive. I wanna hand someone some Important Work Files on a 128gb USB Pregnancy Test.
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foone Sep 3
Replying to @Foone
it has been [0] days since I stuck a metal tool into a device to trick it into thinking I peed on it
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foone Sep 3
Replying to @Foone
Yeah, I can't get it to read anything but MANUAL. (which I don't have: I already tossed it) Maybe just using water means it didn't light up enough places on the indicator paper? or maybe I damaged it while opening it...
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foone Sep 3
Replying to @Foone
and yes, it's surprisingly hard to read. You'd think if they were sticking LEDs in the thing, they could have stuck one near the screen and given it a backlight. That'd at least help you read it.
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foone Sep 3
Replying to @Foone
in any case, the final tl;dr: don't waste your time and money on the digital readers. Just get the cheap analog ones, specifically the kind that are just a box of test strips. For the price of this device you can get like 25 test strips, and it'll create less e-waste.
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foone Sep 3
Replying to @Foone
uhhhhhhhhhhhhhh
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foone Sep 3
Replying to @Foone
Easy to use! Find out if your glass of water is pregnant in only 20 seconds!
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foone Sep 3
Replying to @Foone
walmart also sells this box, which has two tests (one analog and one digital) in the same box, and they suggest you confirm with the digital one. That's kinda insultingly pointless if it's the same test strips in both of them...
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foone Sep 3
Replying to @Foone
Anyway, if you want to support me buying stupid things like pregnancy tests just to take them apart, feel free to send me a dollar or two on ko-fi!
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foone Sep 3
Replying to @Foone
or set up a monthly donation on patreon. Thanks!
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