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.

Continue reading “Energy Harvesting Wristwatch Uses a Versatile Photodiode”

Wake Up To Fresh Coffee!

Be careful what you say when you are shown a commercial product that you think you could make yourself, you might find yourself having to make good on your promise.

When he was shown a crowdfunded alarm clock coffee maker, [Fabien-Chouteau] said “just give me an espresso machine and I can do the same”. A Nespresso capsule coffee machine duly appeared on his bench, so it was time to make good on the promise.

The operation of a Nespresso machine is simple enough, there is a big lever on the front that opens the capsule slot and allows a spent capsule to drop into a hopper. Drop in a new capsule, pull the lever down to load it into the mechanism, then press one of the buttons to tell it to prime itself. After a minute you can them press either of the large cup or the small cup buttons, and your coffee will be delivered.

To automate this with an alarm clock there is no necessity to operate the lever, it’s safe to leave loading a capsule to the user. Therefore all the clock has to do is trigger the process by operating the buttons. A quick investigation with a multimeter on the button PCB found that the voltage present was 15 V, well above the logic level of the STM32F469 board slated for the clock. Thus a simple circuit was devised using a MOSFET to  do the switching.

Finally, the clock software was created for the STM32F469. The chip’s 2D graphics acceleration hardware and the development board’s high quality display make for a very slick interface indeed.

You can see the resulting clock in the video below the break. It’s an alarm clock coffeemaker we’d be proud to have beside our beds, but there’s one slight worry. On a mains-powered device like the Nespresso the low voltage rails are not always mains-isolated, and it’s not clear whether or not this is the case. Maybe we’d have incorporated an opto-isolator, just in case.

Continue reading “Wake Up To Fresh Coffee!”

4-LED Octal Clock Demands Colorful Math

We’ve all seen LED clocks where RGB LEDs are used to display time. It seems like the simpler the interface, the more likely you’d need to do math to figure out the time. This Octal Clock by [Alex Kurrasch] proves the point by using only four LEDs: the top two show hours and minutes, and the bottom two LEDs are multipliers.

Using octal numbering, [Alex] translates the data using a Venn diagram of color mixing. The mapping uses 1 as red, 2 as green, followed by yellow, blue, magenta, and cyan. It ends with 7 as white (all on) and 0 as black (all off).

As the time changes, a fading algorithm changes the display to match. He offers the time of 7:38pm as an example in the grid shown here. Base-8 math is provided; don’t worry, you’ll get really good at this if you make your own wristwatch version… people will learn to never ask you about the time.

The clock uses a ATMega64 running assembly language firmware with a DS1306E+ RTC chip keeping track of time. The enclosure is cool too; [Alex] milled the case out of mahogany and the front and back plates are anodized aluminum. The unique looking diffusers on the LEDs are actually paraffin, a trick that [Elliot Williams] mentioned in his recent article on diffuser materials.

A LED Strip Clock As Linear As Time

We love custom clocks here at Hackaday, and are always thrilled to see each inventive means of time-keeping. In a seldom-seen take on the familiar device, the [Bastel Brothers]’s LED Strip Clock’s sleek profile finds itself in good company.

The clock is a two-metre strip of 60 LEDs; every minute past the current hour corresponds to one lit LED, every fifth LED is turned to red in order to make reading minutes easier. So 3 red LEDs +3 green LEDs=18 minutes, with the hour marked by a third color. Sounds complex, but the [Brothers] are quick to say you get used to it quickly, especially when the 6 o’clock LED is centered at some noticeable object or feature.

Continue reading “A LED Strip Clock As Linear As Time”

An Alien-Themed… Cuckoo Clock?

If you are a follower of the sci-fi horror film genre then it is likely that you will be familiar with the Alien series of movies. Images of Sigourney Weaver bearing a significant amount of firepower, or of John Hurt’s chest being rent asunder by an emerging creature will be brought to mind, it’s one of those franchises which seems to have entered the public consciousness.

With the release of another movie in the series fast approaching, [Keith Elliott] resolved to mark the occasion with his own Alien themed tribute. What, you might ponder, could he choose? Surely there must be plenty of iconic moments in the films that could provide fertile ground for a tribute project!

So  presumably after a significant period of reflection, he’s built an Alien themed cuckoo clock. Something of an off-the-wall choice, you might say, but he persevered with it. The main body of the clock is the torso and head of an unfortunate human crew member, the face of the clock is formed by an alien facehugger on his face, and the cuckoo is not a bird in the manner of the Alpine originals, but a chest-bursting alien that issues forth from the torso.

There is a video, which we’ve posted below. Perhaps the chestburster action needs a little more spontaneity and to be a little less rhythmic, but we’ll leave it to you to decide whether it is inspired or merely kitsch.

Continue reading “An Alien-Themed… Cuckoo Clock?”

Mains Clocking A Microcontroller

[Lujji] is playing around with the STM8 microcontroller. In reviewing the official documentation for this chip, he read the external clock can be a sine wave, a triangle wave, or a square wave with a 50% duty cycle. The minimum CPU frequency is 0 Hz. [Lujji] doesn’t have a signal generator, and presumably, he’s all out of crystals. He does have mains AC, though, so why not clock a microcontroller with wall power?

Using mains power as a frequency standard is a concept a hundred years old. Synchronous motors turn at a rate proportional to the mains frequency, and this has been used in clocks for decades. If you’re really clever, you can clock digital circuits with mains AC, but we’ve never seen someone replace a tiny crystal in a microcontroller circuit with mains power.

After an experiment to prove the concept, [Lujji] went on to construct a circuit that wasn’t as dumb as connecting the microcontroller directly to a wall socket. The direct approach didn’t work that well anyway — the STM8 didn’t like low frequency clocks with slow edges. [Lujji] needed a clock with cleaner edges, and a 555 configured as a comparator fit the bill.

The completed circuit sends mains power through an optocoupler to drive a 555 configured as a comparator. The output is a clean 50Hz clock that is connected to the OSCIN pin on an STM8. This is now a chip running at 50Hz, and yes, it works. [Lujji] set up a circuit to write ‘Hello World’ on an old Nokia LCD. That took about three minutes. It works, though, even though it’s completely useless. Maybe this can be applied to some novel timekeeping similar to that one-instruction-per-day clock we looked earlier in the year.

Hackaday Prize Entry: Obsolete Time Lite

There are very few constants in the world of home-made electronics. Things that you might have found on the bench of a mid-1960s engineer working with germanium PNP transistors just as much as you might find on the bench of one in 2017 working on 32-bit microcontrollers. One of these constants is the humble Altoids tin. The ubiquitous mint container is as handy a size for the transistor circuits of previous decades as it is for the highly integrated circuits of today, and has become something of a standard form factor.

One thing you might not expect in an Altoids tin though is a vacuum tube, even one protruding through the lid. [opeRaptor] though has done just that, though, with a very nicely executed design for a NIXIE clock in your favorite mint container. We’re writing this up as a Hackaday Prize entry so at this stage in the competition the boards are still in design for the prototype, but the difficult power supply to make 180 V DC from a single cell is already proven to work, as it the clock circuitry. The final clock will be a very compact device given the size of the tin, and will contain an ESP8266 board for wireless network connectivity.

For a project at this early stage, there is frustratingly little real work to go on aside from some renders, but there is at least a video showing the PSU working driving a NIXIE, which we’ve put below the break.

Continue reading “Hackaday Prize Entry: Obsolete Time Lite”