An Arduino Watch Without A Clock

August 24, 2018 by Tom Nardi 27 Comments

When you show up at a party wearing this bare PCB watch, there are effectively two possible reactions you might receive from the other people there. Either they are going to snicker at the nerd who’s wearing a blinking circuit board on their wrist in public, or they are going to marvel at the ridiculously low part count. We’ll give you one guess as to which reaction you’d likely get at any event Hackaday is involved in.

Designed and built by [Electronoobs], this extremely simple watch consists of a ATmega328P microcontroller, a dozen LEDs with their associated 200 Ω resistors, and a battery. There’s also a single push button on the front which is used to not only set the watch, but turn the LEDs on when you want to check the time. Short of dropping down to one LED and blinking out the time, it’s hard to imagine a timepiece with fewer components than this.

You’re probably wondering how [Electronoobs] pulled this off without an external clock source for the ATmega328P chip. The chip actually has an internal 8 MHz oscillator that can be used, but you need to flash the appropriate bootloader to it first. Accordingly, the backside of the PCB has both SPI and a UART solder pads for external bootloader and firmware programming.

As you might expect, there’s a downside to using the internal oscillator: it’s not very good. The ATmega328P spec sheet claims a factory calibrated accuracy of ±10%, and [Electronoobs] has found that equates to a clock drift of around 15 seconds per day. Not exactly great, but considering the battery only lasts for two days anyway, it doesn’t have much of an impact in this case.

Compared to other “analog” LED watches we’ve seen, the simplicity of this build is really quite remarkable. The closest competitor we’ve seen so far is this slick binary watch.

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A Surprisingly Practical Numitron Watch

August 16, 2018 by Tom Nardi 6 Comments

Regular Hackaday readers are surely familiar with Nixie tubes: the fantastically retro cold cathode display devices that hackers have worked into all manner of devices (especially timepieces) to give them an infusion of glowing faux nostalgia. But unfortunately, Nixie displays are fairly fragile and can be tricky to drive due to their high voltage requirements. For those who might want to work with something more forgiving, a possible alternative is the Numitron that uses incandescent filaments for each segment.

There hasn’t been a lot of prior-art that utilizes Numitrons, but that might be changing, given how fantastic this wristwatch created by [Dycus] looks. With a multi-day battery life, daylight readability, and relatively straightforward construction, the Filawatch is likely to end up being something of a reference design for future Numitron watches.

[Dycus] has gone through three revisions of the Filawatch so far, with probably at least one more on the way. The current version is powered by a ATmega328 microcontroller with dual 16-bit LED drivers to control the filaments in the KW-104S Numitron display modules. He’s also included an accelerometer to determine when the wearer is looking at the display, and even a light sensor to control the brightness of the display depending on the ambient light level.

If there’s a downside to Numitron displays, it’s their monstrous energy consumption. Just like in the incandescent light bulbs most of us have been ditching for LED, it takes a lot of juice to get that filament glowing. [Dycus] reports the display draws as much as 350 mA while on, but by lighting it up for only five seconds at a time it can be checked around 150 times before the watch needs to be recharged.

Its been a few years since we’ve seen a Numitron watch, and it’s interesting to see how the state of the art has advanced.

[via /r/electronics]

Internet Of Tea: Coaster Watches For Optimum Drinking Temperature

August 14, 2018 by Dan Maloney 3 Comments

Ah, the age-old question: at what temperature does one’s tea need to be for maximum enjoyment? It’s subjective, of course, but subjective in a way that makes everyone else’s opinion demonstrably wrong. What’s worse, the window of opportunity for optimum tea temperature is extremely narrow. What’s a tea drinker to do?

Throw a little technology at the problem, of course, in the form of this Internet of Tea smart coaster. Through careful experimentation, [Benjojo] determined the temperature of his favorite mug when the tea within was just right for drinking and designed a coaster to alert him to that fact. The coaster is 3D-printed and contains an MLX90616 IR temperature sensor looking up at the bottom of the mug. An ESP8266 lives inside the coaster too and watches for the Optimum Tea Window to open, sending an alert via Discord when the time is right. Yes, he admits that a simple blinking LED on the coaster would keep his tea habit metadata from being slurped up by the international tea intelligence community, but he claims he has nothing to hide. Good luck with that.

What’s next for [Dane]’s tea preparation? Perhaps he can close the loop and automate the whole pre-consumption process.

Incredible 3D Printed Overwatch Airsoft Pistol

July 30, 2018 by Tom Nardi 4 Comments

If you ever needed evidence that gamers are some of the most dedicated individuals in all of fandom, then look no further than this fantastic 3D printed recreation of the “Pulse Pistol” as featured in the immensely popular “Overwatch”. Built by the guys at [Danger Doc], this replica doesn’t just look the part, it’s also a fully functional Airsoft gun. In the detailed build video after the break, the year-long design and construction of the gun is broken down for your viewing pleasure.

Because the end goal was to make something that looked as though it came from the game itself, a lot of time was put into making sure that the externals were faithful to the digital version while still able to contain all the hardware they needed to cram in there. This is a fully auto gun, so it needed a battery and motors, as well as a way to feed the firing mechanism Airsoft BBs that didn’t require an anachronistic magazine sticking out.

They combined a off-the-shelf firing mechanism and high-capacity magazine but it took plenty of custom designed parts to get everything mated up. The magazine has a clockwork mechanism to advance the BBs which required the user to manually crank up, but this was replaced with an electric motor to make things a little more futuristic. In addition to all the LEDs on the body of the gun, there’s also an internal array of ultraviolet SMD LEDs to charge the glow-in-the-dark “tracer” BBs as they move through the magazine. In low light, this gives the shots from the gun something of a laser effect.

We’ve seen 3D printed guns from games before, but rarely with this attention to detail and engineering. Honestly, this even gives some real 3D printed guns a run for their money.

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A BCD Wristwatch You’d Want To Wear

July 24, 2018 by Jenny List 4 Comments

Timepieces are a staple of Hackaday, we have featured so many of them over the years that for us to become really excited by a fresh one it must be particularly special. The days when simply breaking out the Nixies was enough are long past.

So this binary wristwatch project by [Sverd Industries] definitely caught our eye. Not for being particularly novel, after all binary LED clocks are not in themselves hard, but for the exceptionally high quality of its construction. It’s a simple enough design, with a real-time clock chip and an ATmega328 in its most power-sipping mode on a circular PCB with an array of LEDs as the display, and all contained within a 3D-printed shell.

This design has real quality, the discrete components are tucked underneath the board leaving the ICs on the top with only the LEDs for company. The glass front is glued into place, and the shell is professionally 3D-printed. Power comes from a single CR2032, and to save battery life the LEDs are only activated by the press of a concealed button. We would wear this watch. For that matter, you would wear this watch. Take a look at the video below the break, and we’re sure you’ll agree. Looks like a few are even available over on Tindie.

This isn’t the first binary watch we’ve featured, so it’s tough to pick a comparison. This very low BoM example might lack some of the polish of the one presented here, but it has the same ability to catch our eye.

Continue reading “A BCD Wristwatch You’d Want To Wear” →

3D Printer Guardian Watches For Worst-case Failures

July 16, 2018 by Donald Papp 17 Comments

Some devices have one job to do, but that job can have many facets. To [jmcservv], an example of this is the job of protecting against worst-case failures in a 3D printer, and it led him to develop the 3D Printer Watchdog Guardian. When it comes to fire, secondary protection is the name of the game because it’s one thing to detect thermal runaway and turn off a heater, but what if that isn’t enough? The MOSFET controlling the heater could have failed closed and can no longer be turned off in a normal sense. In such cases, some kind of backup is needed. Of course, a protection system should also notify an operator of any serious problem, but what’s the best way to do that? These are the kinds of issues that [jmcservv] is working to address with his watchdog, which not only keeps a careful eye on any heating elements in the system, but can take a variety of actions as a result.

Some outcomes (like fire) are bad enough that it’s worth the extra work and cost of additional protection, and that’s the thinking that has led [jmcservv] to submit his watchdog system for The Hackaday Prize.

LEDs Make An “Analog” Wristwatch

July 5, 2018 by Lewin Day 6 Comments

If you just came down in the last shower, you’re probably used to living in a world where LEDs are cheap, awesome, and practically everywhere. Spare a thought for those of us who lived before the invention of high brightness LEDs – these things still amaze us! A great example of how far we’ve come is this “analog” watch build by [Kevin], featuring no less than 73 of the critters.

The microcontroller running the watch is an STM32, chosen for its easy programmability. It’s running the LEDs in an emulation of the dial of an analog clock, hence the high part count. Naturally, it’s no simple task to cram 73 LEDs and all the necessary connections into the confines of a watch-sized PCB. [Kevin] goes into great detail about the challenges involved, from routing the traces to a tricky power draw problem caused by some odd blue LEDs.

Watch builds are always fun, and they make great conversation pieces for when you want to amaze strangers with your tales of battles fought in the PCB design suite. Now check out this similar build with an entirely different style.