Wristwatch PCB Swaps Must Be In The Air

August 8, 2021 by Mike Szczys 19 Comments

Are we seeing more wristwatch PCB swapping projects because more people are working on them, or because we saw one and they’re on our mind? The world may never know, but when it comes to design constraints, there’s a pretty fun challenge here both in fitting your electronic wizardry inside the confines of an injection molded case, and in the power budget to make your creation run on a sippy straw of battery power.

Just this morning we came across [Joey Castillo’s] sensor-watch project. He chose the Casio F-91W as the donor wristwatch. It’s got that classic Casio look of a segment LCD display capable of displaying hours, minutes, and seconds, as well as day and date. But the added bonus is that we know these have decent water resistance while still providing three buttons for user input. Sure, it’s less buttons than the pink calculator watch we saw [Dave Darko] working on earlier in the week, but which would you trust in the pool?

Replacement PCB sized to use the same battery contact and CR2016 for power [via @josecastillo]

We see that [Joey] also chose to use the ATSAML22 microcontroller and sheds some light on why: it includes a built-in segment LCD controller! If you’re a peripheral geek like us, you can read about the SLCD controller on page 924 of the datasheet (PDF), it’s a whole datasheet onto itself.

The sensor part of the sensor-watch is a flex PCB breakout that allows you to swap in whatever sensor fits your needs. The first to be reflowed at [Joey’s] bench is a BME280 humidity sensor, which is most obviously useful for the included temperature measurements, but maybe it could also alarm at moisture ingress? [Joey] says you can swap in other parts as long as they’re in the QFN or LGA size range. We think an IMU is in order since there’s a lot of fun interaction there like the watch reacting to being positioned in front of your face, or to take tap-based inputs.

We think beginning with a donor watch is brilliant since pulling off a case, especially one that keeps water out, is 97% of the battle. But when your UI is unique to the watch world, sometimes you need to start from scratch like this wooden word clock wristwatch.

Living The Dream: New PCB For A Dirt-Cheap Calculator Watch

August 1, 2021 by Kristina Panos 6 Comments

Well, this hack has us tickled pink. We love the idea of buying some really cheap piece of technology and doing something amazing with it, and this is a textbook example of that. [davedarko] found the cutest little calculator watch on Ali Express and is working on making a new PCB for it. The plan is to use an ARM processor and Arduino and add a few extras like 24-hour mode and a pink (or potentially RGB) backlight. The new brain will be an ATSAML22G18A, which has an on-board LCD controller and exactly one I/O pin to spare without charlieplexing the buttons.

One of [davedarko]’s primary goals is to keep the LCD and figure out how to talk to it. The first order of business was reverse engineering the watch’s LCD controller by sussing out the secrets from beneath the black blob of epoxy. This was an eye-opening experience as [davedarko] had never worked directly with LCDs before. A strange reading made him bust out the oscilloscope. Long-ish and informative story short, [davedarko] found out that it uses a bias of 1/2 for generating the wave necessary to multiplex the segments and keep the signal alternating. This is definitely one to watch!

We love timepieces around here and have seen all kinds of hacks, especially on Casio watches. Want dark mode? Done. Enable the hidden countdown timer? We’ve got that, too. And have you ever wondered just how water-resistant the F91W is?

Stop Touching My Face

July 13, 2021 by Orlando Hoilett 12 Comments

We all have a habit or two that we’re not terribly proud of and have probably thought of any number of ways to help rid ourselves of them. Well, [Friedlc] wondered if he could create a mechanism that would get him to stop touching his face using a bit of negative conditioning. He rigged up a head brace that slaps his forehead whenever reaching for his face.

The first thing he needed to do was to detect a hand approaching his face. He decided to use a few cheap IR motion sensors he had laying around but noted they had a few limitations. He had a tough time tuning the sensitivity of the motion sensors to prevent false positives and they were completely useless in direct sunlight as the sun’s radiation saturated the photodetector. Despite these problems, [Friedlc] figured he would mostly need his device indoors so he stuck with the IR detectors.

For the “hitter” as he called it, he thought of a few different ideas. Maybe a rotating drum with a flap that would hit his hand or maybe a hitting arm on a bar linkage. He admitted that his rudimentary mechanical design knowledge made thinking of the perfect “hitter” a bit challenging, but like any good hacker, [Friedlc] just kept working at it. He decided on using a cam mechanism which allowed him to separate the motor from the hitting action. This choice actually put a lot less load on the motor which kept the motor from stalling and giving him other kinds of trouble.

[Friedlc] was pretty proud of his invention and noted that it really helped him stop touching his face as the successive strikes to the head were definitely quite a deterrent. This certainly isn’t the first time we’ve seen a Pavlovian Conditioning project on Hackaday. We could probably all use a bit of help curing a few bad habits. But maybe you prefer positive reinforcement instead.

Continue reading “Stop Touching My Face” →

Skin-Mounted Wearable Bend Sensor Gets Close And Personal

July 10, 2021 by Donald Papp 1 Comment

[Mikst] has been working on wearable electronics and sensors for a long time, and shared the results of a different kind of bend sensor that fits directly onto the skin. It’s true that this kind of sensor design isn’t re-usable, but it is also very simple and inexpensive. It’s just a proof of concept right now, but we could see it or some of the other ideas [Mikst] tries, used in niche wearable applications where space is critical, like cosplay.

At its heart the sensor is made from two strands of conductive thread and a small strip of stretchy, conductive fabric common in wearable e-textiles. It is stuck directly to the skin using a transparent, non-woven medical adhesive dressing that is particularly good at conforming to contoured areas of the body. In this case, it is used to stick the stretchy piece of conductive fabric directly onto [Mikst]’s knuckle, where it responds to even small movements. You can watch a multimeter measuring the resistance changes in the video, embedded below.

We’ve seen [Mikst]’s work before in finding unusual solutions to e-textile problems, such as a three-conductor pivoting connection used to mount a wearable hall effect sensor.

Continue reading “Skin-Mounted Wearable Bend Sensor Gets Close And Personal” →

Flexible Prototyping For E-Textiles That Doesn’t Cost An Arm And A Leg

June 22, 2021 by Kristina Panos 3 Comments

Let’s face it: pretty much everything about e-textiles is fiddly. If wearables were easy, more people would probably work in that space. But whereas most circuit prototyping is done in two dimensions, the prototyping of wearables requires thinking and planning in 3D. On top of that, you have to figure out how much conductive thread you need, and that stuff’s not cheap.

[alch_emist] has a method for arranging circuits in 3D space that addresses the harsh realities of trying to prototype wearables. There’s that whole gravity thing to deal with, and then of course there are no straight lines anywhere on the human body. So here’s how it works: [alch_emist] made a bunch of reusable tie points designed to work with an adhesive substrate such as felt. They laser-cut a set of acrylic squares and drilled a hole in each one to accommodate a neodymium magnet. On the back of each square is a small piece of the hook side of hook-and-loop tape, which makes the tie points stay put on the felt, but rearrange easily.

We love the idea of prototyping with felt because it’s such a cheap and versatile fabric, and because you can easily wrap it around your arm or leg and see how the circuit will move when you do.

Not quite to this planning stage of your next wearable project? Magnets and conductive thread play just as well together in 2D.

Forget Smart Watch; Build A Smart Hat

June 21, 2021 by Al Williams 4 Comments

Smart watches are pretty common today, but how many people do you know with a smart hat? [Oliver] built Wilson which he bills as “the IoT hat.” We wonder if the name was inspired by the Home Improvement character of the same name who only appeared as a hat above the fence line. You can see a video of the project, below.

The project is pretty straightforward for hardware. An LED strip, an Arduino, and a Bluetooth module. Oh. And a hat. The software, as you might expect, is a bit more complex. It allows you to display SMS messages to your hat.

Continue reading “Forget Smart Watch; Build A Smart Hat” →

Roller Skating, Wile E. Coyote-Style

June 13, 2021 by Kristina Panos 36 Comments

They say you learn something new every day, and they’re usually right about that. Today’s tidbit is that just anybody (including [Ian Charnas]) can exchange money for jet engines, no questions asked. Scary, huh? So once [Ian] secured the cutest little engine, he took a poll regarding possible uses for it. Jetpack rollerskating won, that’s obvious enough. So let’s get into those details.

[Ian] procured this particular jet engine from an outfit called CRX Turbines. It tops out at 98,000 RPM and 30 kg (66 lbs.) of thrust. Essentially, he is pulsing the engine’s ECU with PWM from an Adafruit RadioFruit and controlling it with a pair of stripped drills that are just being used for their convenient grips and switches. One is wired as a dead man’s switch, and the other controls the throttle signal.

In order to run the thing and test the thrust a bit before strapping it on his back, [Ian] went about this the smart way and welded together a sliding stand. And he didn’t use just any old Jansport backpack, he welded together a frame and roll cage for the engine and attached it to a full-body harness. There’s also a heat shield to keep his backside from catching fire.

At first he tested the jet pack with shoes instead of skates to make sure it was going to behave as he predicted. Then it was time to bust out the roller skates. [Ian] achieved a top speed of 17 MPH before losing his balance, but he knew it could go faster, so he invited some roller derby skaters to try it out. One of them went over 30 MPH! Be sure to check it out in the build and demo video after the break.

If you’re at all familiar with [Ian]’s videos, you know that he usually raffles off the build and gives the money to charity. Well, not this time! That wouldn’t be prudent. Instead, he’s going to choose the best suggestion for what to attach it to, build it, and raffle that off. Hopefully, he stays away from airports with that thing on his back.

Continue reading “Roller Skating, Wile E. Coyote-Style” →