The Rise Of Fake Casio Scientific Calculators

December 29, 2025 by Maya Posch 40 Comments

Scientific calculators are an amazing invention that take pocket calculators from being merely basic arithmetic machines to being pocket computers that can handle everything from statistics to algebra. That said, there are a few layers of scientific calculators, starting with those aimed at students. This is where Casio is very popular, especially because it uses traditional algebraic notation (VPAM) that follows the written style, rather than the reverse-polish notation (RPN) of HP and others. However, much like retro Casio wristwatches, it appears that these Casio calculators are now being (poorly) faked, as explained by [Another Roof] on YouTube.

The advanced fx-991 models are updated every few years, with the letters following the model indicating the year, such as fx-991EX standing for the 2015-released model. This was the model that got purchased online and which turned out to be fake. While the fx-991CW is newer, it changes the entire interface and is rightfully scolded in the video. Arguably this makes it the worst Casio scientific calculator in history.

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Testing 8 Solder Flux Pastes After Flux Killed A GeForce2 GTS

December 20, 2025 by Maya Posch 18 Comments

Riesba NC-559-ASM flux being applied. (Credit: Bits und Bolts, YouTube)

Flux is one of those things that you cannot really use too much of during soldering, as it is essential for cleaning the surface and keeping oxygen out, but as [Bits und Bolts] recently found, not all flux is made the same. After ordering the same fake Amtech flux from the same AliExpress store, he found that the latest batch didn’t work quite the same, resulting in a Geforce 2 GTS chip getting cooked while trying to reball the chip with uncooperative flux.

Although it’s easy to put this down to a ‘skill issue’, the subsequent test of eight different flux pastes ordered from both AliExpress and Amazon, including — presumably genuine — Mechanic flux pastes with reballing a section of a BGA chip, showed quite different flux characteristics, as you can see in the video below. Although all of these are fairly tacky flux pastes, with some, the solder balls snapped easily into place and gained a nice sheen afterwards, while others formed bridges and left a pockmarked surface that’s indicative of oxygen getting past the flux barrier.

Not all flux pastes are made the same, which also translates into how easy the flux remnants are to clean up. So-called ‘no clean’ flux pastes are popular, which take little more than some IPA to do the cleaning, rather than specialized PCB cleaners as with the used Mechanic flux. Although the results of these findings are up for debate, it can probably be said that ordering clearly faked brand flux paste is a terrible idea. While the top runner brand Riesba probably doesn’t ring any bells, it might be just a Chinese brand name that doesn’t have a Western presence.

As always, caveat emptor, and be sure to read those product datasheets. If your flux product doesn’t come with a datasheet, that would be your first major red flag. Why do we need flux? Find out.

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Review: Cherry G84-4100 Keyboard

December 12, 2025 by Jenny List 46 Comments

The choice of a good keyboard is something which consumes a lot of time for many Hackaday readers, judging by the number of custom input device projects which make it to these pages. I live by my keyboard as a writer, but I have to admit that I’ve never joined in on the special keyboard front; for me it’s been a peripheral rather than an obsession. But I’m hard on keyboards, I type enough that I wear them out. For the last five years my Hackaday articles have come via a USB Thinkpad keyboard complete with the little red stick pointing device, but its keys have started parting company with their switches so it’s time for a replacement.

I Don’t Want The Blackpool Illuminations

A picture of the Blackpool illuminations at night against a dark sky. — Is it a gamer’s keyboard, or the Blackpool seafront at night? I can’t tell any more. Mark S Jobling, Public domain.

For a non keyboard savant peering over the edge, this can be a confusing choice. There’s much obsessing about different types of mechanical switch, and for some reason I can’t quite fathom, an unreasonable number of LEDs.

I don’t want my keyboard to look like the Blackpool Illuminations (translation for Americans: Las Vegas strip), I just want to type on the damn thing. More to the point, many of these “special” keyboards carry prices out of proportion to their utility, and it’s hard to escape the feeling that like the thousand quid stereo the spotty kid puts in his Opel Corsa, you’re being asked to pay just for bragging rights.

Narrowing down my needs then, I don’t need any gimmicks, I just need a small footprint keyboard that’s mechanically robust enough to survive years of my bashing out Hackaday articles on it. I’m prepared to pay good money for that.

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Cheap 10x10cm Hotplate Punches Above Its Weight

December 10, 2025 by Arya Voronova 14 Comments

For less than $30 USD, you can get a 10×10 centimeter hotplate with 350 Watts of power. Sounds mighty fine to us, so surely there must be a catch? Maybe not, as [Stefan Nikolaj]’s review of this AliExpress hotplate details, it seems to be just fine enough.

At this price, you’d expect some shoddy electronics inside, or maybe outright fiery design decisions, in the vein of other reviews for similar cheap heat-producing tech that we’ve seen over the years. Nope – the control circuitry seems to be more than well-built for our standards, with isolation and separation where it matters, the input being fused away, and the chassis firmly earthed. [Stefan] highlights just two possible problem areas: a wire nut that could potentially be dodgy, and lack of a thermal fuse. Both can be remedied easily enough after you get one of these, and for the price, it’s a no-brainer. Apart from the review, there’s also general usage recommendations from [Stefan] in the end of the blog post.

While we’re happy to see folks designing their own PCB hotplates or modifying old waffle irons, the availability of cheap turn-key options like this means there’s less of a reason to go the DIY route. Now, if you’re in the market for even more build volume, you can get one of the classic reflow ovens, and maybe do a controller upgrade while you’re at it.

Target The Best AA, And Take No Flak

November 9, 2025 by Tyler August 68 Comments

In this era of cheap lithium pouch cells, it might seem mildly anachronistic to build AA batteries into a project. There are enough valid reasons to do so, however, and enough legacy hardware that still takes AAs, that it’s worth spending some time deciding which batteries to use. Luckily for us, [Lumencraft] over on YouTube has done the legwork in the video embedded below, and even produced a handy-dandy spreadsheet.

Each battery in the test underwent three separate tests. There was the “leave it in a flashlight ’til it dies” test for real-world usage, but also discharge curves logged at 250mA and 2A. The curves for each are embedded in the spreadsheet so you can see what to expect, along with the calculated capacity at each discharge rate. 2A seems like a fairly brutal load for AAs, but it’s great to see how these cells react to extremes. The spreadsheet also includes the cell’s cost to create a value ranking, which will be of great use to our readers in the USA, where it appears [Lumencraft] is buying batteries. The world market is likely to have the same batteries available, but prices may vary by region, so it’s worth double-checking.

In the video, [Lumencraft] also takes the time to explain the four battery types commonly found in AA format, and the strengths and weaknesses of each chemistry that might cause you to prefer one over another for specific use cases, rather than going by his value rankings. Unsurprisingly, there’s virtually no reason other than cost to go for alkaline batteries in 2025. However, lithium-ion batteries in AA form don’t really outperform NiMH enough to make the added cost worthwhile in all applications, which is why the overall “best battery” is a “PowerOwl” NiMH. Li-ion’s unspectacular performance is likely in part due to the inefficiencies introduced by a built-in buck converter and safety circuitry. On the other hand, some people might really appreciate that extra safety compared to bare 18650 cells.

The results here aren’t too dissimilar to what we saw earlier this year, but we really appreciate [Lumencraft] publishing his results as a spreadsheet for easy reference. The only caveat is that he’s taking manufacturers at their word as to how many cycles the batteries will last.

Oh, and just to be 100% clear — we are talking about double-A batteries, not Anti-Aircraft batteries. If anyone has an anti-aircraft battery hack (especially if that hack includes double-A batteries powering the AA batteries), please send in a tip.

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A Nuclear Physics Lab In Your Pocket

October 25, 2025 by Al Williams 17 Comments

If you want to work with radioactive material, a cheap Geiger counter isn’t really what you want. According to [Project 326], you need a gamma ray spectrometer. The video below reviews the Radiacode 110. The channel has reviewed other Radiacode products, and they haven’t always been pleased with them, apparently. Is the 110 better?

The little spectrometer uses a scintillation crystal and performs a spectrogram on the result. It has a large library of materials so, at least for radioactive materials, you can point it at something and tell what kind of material you are dealing with and how radioactive it is.

While the smartphone app seems well done, the Windows application left something to be desired. Even still, it was able to identify several isotopes. The device can even pick up some alpha emitters that don’t directly register. However, it can identify some materials by different decomposition products. Unlike some earlier models, this device is supposed to be highly sensitive and high-resolution.

To confirm this, [Project 326] built a lead shielding structure and read a reference sample. Crunching some numbers confirmed that the claimed performance was accurate. It could even read very low-energy sources, though there were some limitations. The ergonomics of the device could be better, apparently, but it does deliver on performance.

Do you need a gamma ray spectrometer? We don’t know, but we suspect if you do, you don’t need us to tell you.

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Fnirsi IPS3608: A Bench Power Supply With Serious Flaws

September 20, 2025 by Maya Posch 23 Comments

Fnirsi is one of those brands that seem to pop up more and more often, usually for portable oscilloscopes and kin. Their IPS3608 bench power supply is a bit of a departure from that, offering a mains-powered PSU that can deliver up to 36 VDC and 8 A in a fairly compact, metal enclosure. Recently [Joftec] purchased one of these units in order to review it and ended up finding a few worrying flaws in the process.

One of the claims made on the product page is that it is ‘much more intelligent than traditional power supplies’, which is quite something to start off with. The visual impression of this PSU is that it’s somewhat compromised already, with no earth point on the front next to the positive and negative banana plug points, along with a tilting screen that has trouble staying put. The USB-C and -A ports on the front support USB-PD 3.0 and a range of fast charge protocols

The ‘intelligence’ claim seems to come mostly from the rather extensive user interface, including a graphing function. Where things begin to fall apart is when the unit locks up during load testing presumably due to an overheating event. After hooking up an oscilloscope, the ripple at 1 VDC was determined to be about 200 mV peak-to-peak at 91 kHz. Ripple increased at higher voltages, belying the ’10 mV ultra-low ripple’ claim.

A quick teardown revealed the cause for the most egregious flaw of the unit struggling to maintain even 144 Watt output: a very undersized heatsink on the SMPS board. The retention issues with the tilting issue seemed to be due to a design choice that prevents the screen from rotating without breaking plastic. While this latter issue could be fixed, the buggy firmware and high ripple on the DC output make this €124 ‘285 Watt’ into a hard pass.

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