Energy Harvesting Wristwatch Uses a Versatile Photodiode

There’s some interesting technology bundled into this energy harvesting wristwatch. While energy harvesting timepieces (called automatic watches) have been around for nearly 240 years, [bobricius] has used parts and methods that are more easily transferable to other projects.

Unlike early mechanical systems, this design uses the versatile BPW34 PIN photodiode (PDF warning). PIN photodiodes differ from ordinary PN diodes in that there’s a layer of undoped ‘intrinsic’ silicon separating the P and N doped layers. This reduces the utility of the diode as a rectifier, while allowing for higher quantum efficiency and switching speed.

They are typically used in the telecommunications industry, but have a number of interesting ‘off label’ applications. For example, the BPW34 can be used as a solid-state particle detector (although for detecting alpha particles you’re better off with something in a TO-5 package such as the Hamamatsu S1223-01). The fast response speed means you can send data with lasers or ambient light at high frequencies – a fun use for an LED lighting system or scrap DVD-RW laser.

Some common solar panels are essentially large PIN photodiodes. These are the brownish panels that you’ll find in a solar-powered calculator, or one of those eternally waving golden plastic neko shrines. They specifically offer excellent low-light performance, which is the basis of the energy harvesting used in this project.

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The Numitron Geekwatch

numitron_uhr_gehause_i

[Johannes] wanted to develop an unusual way to display time on a custom wristwatch. LED’s were too common, and mechanical indicators with small engines were too expansive, but Nixie tubes were just right. His design for the Numitron Geekwatch utilized two boards that were soldered together at a right angle, with a 3D printed enclosure made of semi-transparent PLA.

Future designs of this will improve on the button functionality as well as the housing of the wristwatch to protect the fragile tubes from external forces.

After the break is a video (in German) with [Johannes] going through the steps needed to make one of these of your very own:

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Tell Time and Blink an LED on Your Wrist with WatchDuino

Watchduino Open Source Watch

Is your hipster wrist having a hard time waiting for the debut of the iWatch? There’s a new open hardware/software project out that could help calm your nerves. The WatchDuino is exactly what it sounds like, an Arduino-based wrist watch.

The component list is short and inexpensive. The meat and potatoes consist of an ATMega328, crystal, Nokia LCD screen and LiPo battery. The USB-rechargeable battery lasts about a week before needing to be such. Besides presenting the Time and Date in both analog or digital formats (as you would expect) there is an alarm and timer. Additionally, there are 2 games, Pong and Snake. Any lack of features is made up for the fact that the software is open and can be modified and added to by the community. We’re sure the development of this watch will be quick and significant.

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How Much Can You Cram Into a Wristwatch

Creating wearable electronics that are functional and not overly bulky is very, very hard. [Zak], though, makes it look easy. He started his DIY digital wrist watch to see how much he could cram into a watch-sized device. The finished product is really incredible, and one of the most amazing DIY watches we’ve ever seen.

The electronics for the watch include an ATMega328p, a DS3231M Real Time Clock, a Microchip battery charger, and a few resistors and caps. The display is an OLED, 1.3″ wide and only 1.5 mm thick, contributing to the crazy 10mm overall thickness of the watch.

The software is where this watch really shines. Along with the standard time and date functions, [Zak] included everything and more a wrist watch should have. There is an interface to set up to ten alarms on different days of the week, a Breakout and ‘Car Dodge’ game, a flashlight with integrated ‘rave’ mode, and a stopwatch. On top of this, [Zak] included some great animations very similar to the CRT-like animations found in Android.

It’s a fabulous piece of kit, and if any project were deserving of being made into an actual product, this is it.

You can check out [Zak]’s demo of all the functions of his watch below.

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