Modding A Casio W800-H With A Countdown Timer

Stock, the Casio W800-H wristwatch ships with dual time modes, multiple alarms, and a stopwatch – useful features for some. However, more is possible if you just know where to look. [Ian] decided to dive under the hood and enable a countdown timer feature hidden from the factory.

The hack involves popping open the case of the watch and exposing the back of the main PCB. There, a series of jumpers control various features. [Ian]’s theory is that this allows Casio to save on manufacturing costs by sharing one basic PCB between a variety of watches and enabling features via the jumper selection. With a little solder wick, a jumper pad can be disconnected, enabling the hidden countdown feature. Other features, such as the multiple alarms, can be disabled in the same way with other jumpers, suggesting lower-feature models use this same board too.

It’s a useful trick that means [Ian] now always has a countdown timer on his wrist when he needs it. Excuses for over-boiling the eggs will now be much harder to come by, but we’re sure he can deal. Of course, watch hacks don’t have to be electronic – as this custom transparent case for an Apple Watch demonstrates. Video after the break.

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VGA Graphics Card In 74xx Logic

Feeling nostalgic we presume, [Glen Kleinschmidt] set out to build a 640x480x64 VGA controller card from discrete logic chips. If we ignore the 512Kx8 Cypress SRAM video memory, he succeeds, too — and on a very readable, single page A3 schematic. The goal is to interface some of his older 8-bit machines, like the TRS-80 Model 1 and the BBC Micro, but for now he’s running a demo using a 20+ year old PIC16F877 micro.

[Glen] provides all the schematics, Gerbers, and C source code on his website should you be inclined to reproduce one for yourself. He has three versions in the works, with various capabilities (there’s a table on his website). As an alternative, one could always use an FPGA or a custom-built chip such as the SSD1963 to generate video for these micros, but sometimes the urge to go retro is too great to resist. We get the feeling that for [Glen], this is a project unto itself, and being able to interface it to his 8-bit computers is just a convenient excuse.

This isn’t [Glen]’s first retro project, either. Check out his analog computer “bouncing ball” project we covered back in 2017. Have you struggled with the build vs. buy decision, and how do you decide?

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Look Out Below! China’s Heavy-Lift Rocket Due For Uncontrolled Reentry Within Days

On April 28th, China successfully put the core module of their Tianhe space station into orbit with the latest version of the Long March 5B heavy-lift booster. This rocket, designed for launching large objects into low Earth orbit, is unique in that the 33.16 m (108.8 ft) first stage carries the payload all the way to orbit rather than separating at a lower altitude. Unfortunately, despite an international effort to limit unnecessary space debris, the first stage of the Long March 5B booster is now tumbling through space and is expected to make an uncontrolled reentry sometime in the next few days.

The massive booster has been given the COSPAR ID 2021-035-B, and ground tracking stations are currently watching it closely to try and determine when and where it will reenter the Earth’s atmosphere. As of this writing it’s in a relatively low orbit of 169 x 363 km, which should decay rapidly given the object’s large surface area. Due to the variables involved it’s impossible to pinpoint where the booster will reenter this far out, but the concern is that should it happen over a populated area, debris from the 21 metric ton (46,000 pound) booster could hit the ground.

The Tianhe core module.

This is the second launch for the Long March 5B, the first taking place on May 5th of 2020. That booster was also left in a low orbit, and made an uncontrolled reentry six days later. During a meeting of the NASA Advisory Council’s Regulatory and Policy Committee, Administrator Jim Bridenstine claimed that had the rocket reentered just 30 minutes prior, debris could have come down over the continental United States. Objects which were suspected of being remnants of the Long March 5B were discovered in Africa, though no injuries were reported.

China’s first space station, Tiangong-1, made an uncontrolled reentry of its own back in 2018. It’s believed that most of the 8,500 kg (18,700 lb) burned up as it streaked through the atmosphere, and anything that was left fell harmlessly into the South Pacific Ocean. While small satellites are increasingly designed to safely disintegrate upon reentry, large objects such as these pose a more complex problem as we expand our presence in low Earth orbit.

An LED Heartbeat Display You Can Wear On Your Sleeve

There are a few different ways to take a person’s pulse, with varying utility depending on the categories said patient fits in to. [Nitin Nair]’s method doesn’t really have a medical application, but it’s certainly a neat example of what you can do with modern sensors. 

The build combines an EmotiBit sensor platform with an Adafruit Feather and accompanying Charlieplexed LED module. The EmotiBit packs a PPG, or photoplethysmogram sensor, otherwise known as a pulse oximeter, which uses optical methods to detect changes in blood volume beneath the skin. From this data, a pulse rate can be derived, and the LEDs flashed with a heart graphic in concert with the rhythm of the wearer’s heart. The benefit of the PPG in the EmotiBit is that it can be worn on the wearer’s arm, or other location with suitable vascularization. This allows the wearer to place the sensor on the arm, and thus wear their heart on their sleeve.

It’s a cool concept, and we’d love to see it neatly packaged with a smoothly animated fade as a sports accessory. It’d be an easy way to signal how fast your heart rate recovers on a run with friends – the device could brag about your fitness for you. Alternatively, if pulse oximetry isn’t enough for you, go ahead and build an ECG instead!

Homemade EDM Machine Moves From Prototype To Production

Of all the methods of making big pieces of metal into smaller pieces of metal, perhaps none is more interesting than electrical discharge machining. EDM is also notoriously fussy, what with having to control an arc discharge while precisely positioning the tool relative to the workpiece. Still, some home gamers give it a whirl, and we love to share their successes, like this work-in-progress EDM machine. (Video, embedded below.)

We’ve linked [Andy]’s first videos below the break, and we’d expect there will be a few more before all is said and done. But really, for being fairly early in the project, [Andy] has made a lot of progress. EDM is basically using an electric arc to remove material from a workpiece, but as anyone who has unintentionally performed EDM on, say, a screwdriver by shorting it across the terminals in a live outlet box, the process needs to be controlled to be useful.

Part 1 shows the start of the build using an old tap burning machine, a 60-volt power supply, and a simple pulse generator. This was enough to experiment with the basics of both the mechanical control of electrode positioning, and the electrical aspects of getting a sustained, useful discharge. Part 2 continues with refinements that led very quickly to the first useful parts, machined quickly and cleanly from thin stock using a custom tool. We’ll admit to being impressed — many EDM builds either never get to the point of making simple holes, or stop when progressing beyond that initial success proves daunting. Of course, when [Andy] drops the fact that he made the buttons for the control panel on his homemade injection molding machine, one gets the feeling that anything is possible.

We’re looking forward to more on this build. We’ve seen a few EDM builds before, but none with this much potential.

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Mice Develop Inside An Artificial Womb

Well, it looks like those fetus fields from The Matrix (1999) just became a little bit more plausible. Although people-growing is probably a long way off, mice can now mostly develop inside an artificial uterus (try private window if you hit a paywall) thanks to a breakthrough in developmental biology. So far, the mice can only be kept alive halfway through gestation. There’s a point at which the nutrient formula provided to them isn’t enough, and they need a blood supply to continue growing. That’s the next goal. For now, let’s talk about that mechanical womb setup.

Carousel of Care

The mechanical womb was developed to better understand how various factors such as gene mutations, nutrients, and environmental conditions affect murine fetuses in development. Why do miscarriages occur, and why do fertilized eggs fail to implant in the first place? How exactly does an egg explode into 40 trillion cells when things do work out? This see-through uterus ought to reveal a few more of nature’s gestational secrets.

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Hackaday Podcast 116: Three DIY Lab Instruments, Two Tickers, And A MicroCar

Hackaday editors Elliot Williams and Mike Szczys select our favorite hardware hacks of the past week. This episode is packed with DIY lab instruments, including a laser microscope, a Raspberry Pi spectrometer, and a stepper motor tester that can tell you what’s going on all the way down to the microsteps. We wax poetic about what modular hardware really means, fall in love with a couple of stock-ticker robots, and chat with special guest Tom Nardi about his experience at the VCF Swap Meet.


Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (~55 MB)

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