OTM-02 is a 3D printed wristwatch

3d-printed-wristwatch

We love looking at roll-your-own wristwatch projects. Getting a project small enough to carry around on your wrist is a real challenge. But we think the OTM-02 wristwatch really hit the form factor right on the mark.

OTM stands for Open source Time Machine. It’s the work of [Hairy Kiwi] and he managed to bring the guts of the watch in at a thickness between 6.5 and 7mm. That includes the LCD, PCB, piezo diaphragm, and the battery. The PCB itself is a four-layer board built on 1mm thick substrate. It’s running an EFM32 (ARM) microcontroller which comes with hardware USB support. The little door sitting open on the side of the 3D printed enclosure provides access to the micro USB connector which can be used to charge the 150 mAh battery inside. That may not sound like much juice, but if you set the display to show minutes only [Hairy] calculates a battery life approaching 175 days. If you just have to have the seconds displayed you can expect about two weeks between charges.

Like the name says, this project is Open Source.

[Thanks Liam]

Roll your own LoJack clone

diy-lojack

If you’ve ever worried about your car getting stolen this hack can help give you some piece of mind. It’s a cellular enabled geolocation device. These things have been in use for some time, the most common brand we know of is the LoJack. That company gives you a little box to install on the vehicle and if it ever goes missing they can grab the coordinates and forward them to the authorities. This custom version builds a lot into an addon board for an EFM32 board.

The image above shows the main components of the add-on: the GPS module and the GSM modem. Along the top edge of the board is the voltage regulator circuits which aim to keep the standby power to the slightest of trickles so as not to drain the car’s battery. What you can’t see is the SIM card slot which is located on the underside.

You can find the Eagle files for the design at the link above. We’ve embedded the video description of the project after the break.

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Super slim wristwatch build

super-slim-wristwatch-build

This slmwtch lives up to its name. When the LCD screen is folded back onto the PCB the entire thing comes in at just 2.35mm. That’s including a coin-cell battery not shown above. Wow!

Part of what makes this possible is the specialized PCB design. [Anders] didn’t want to add more thickness than the screen and battery so he make a cutout in the PCB design to accept each component. In this image it’s easiest to see on the two SMD resistor in the upper left. They’re held in a void by the two solder connections. Admittedly this is not going to be a mass-production friendly design. And we have concerts about the long-term stability of suspending components by their leads. But as a one-off it’s fantastic! See for yourself in the video after the break.

The control for the watch uses two touch sensitive pads on the back of the PCB. There is no backlight for the display which can be a problem when trying to read the time while outdoors. We wonder if an ePaper display with similar dimensions is available?

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