Thermoelectric Fan Harvests Wood Stove Heat Junkyard Style

April 27, 2018 by 28 Comments

Anyone who heats with a wood stove knows that the experience is completely different from typical central heating. It’s not for everyone, though, and it’s certainly not without its trade-offs. One of the chief complaints is getting heat away from the stove and into other areas of the house, and many owners turn on an electric fan to circulate the heated air.

That’s hardly in the green nature of wood heating, though, and fans can be noisy. So something like this heat-powered stove-top fan can come in handy. Such fans, which use Peltier devices to power a small electric motor, are readily available commercially. [bongodrummer] thought that sounded like no fun, though, and created his own mostly from junk. The Peltier module was salvaged from an old travel fridge and mounted to a heat sink from a computer to harvest heat from the stove. The other side of the Peltier needs to have a heat sink to keep it cooler than the hot side, and [bongodrummer] chose an unconventional bit of salvage for the job — the cylinder of a chainsaw engine. The spark plug hole sprouts the mount for the fan motor, and the cooling fins help keep the Peltier cool. And to prevent overheating of the device, he added a surprise — a car cooling system thermostat to physically lift the device off the stove when it gets too hot. Genius!

The video below shows the build, which was not trivial. But we think the end results are worth it, and it reminds us a little of the woodstove generator we featured a while back.

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Checking The Weather Without A Window

April 27, 2018 by 9 Comments

Making a weather display is great because it’s a simple project that shows off some skills and has an obvious daily use. So [ACROBOTIC Industries] decided to make an easy kit for the Hackaday Prize to make weather displays even more accessible.

Calling it the ESPecter, [ACROBOTIC Industries] wanted to make this a simple project for anyone, regardless of skill with a soldering iron or Arduino toolkit. So they decided to base the guts on common components that can be put together easily, specifically a Wemos Mini D1 with an OLED shield as a bright display. They also designed a cool tiltable 3D-printed enclosure for this small device so that you can orient it to your eye level.

ESPecter breadboarded prototype.

While they already have a breadboarded prototype, and a 3D printed case, some software work remains to make the project really shine. They plan to add nice features like a web interface to configure location and network information, alerts, additional locations, and historical weather data. They also want to create a weather library to display well on a low-resolution screen and add battery operation.

We look forward to seeing the final version later in the Hackaday Prize!

This isn’t the first weather project we’ve seen around here. Other variants include mirror weather displays, an ESP8266-based weather monitoring station, a very low-power weather station, and this roundup of weather displays which might give you some inspiration.

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A Blockchain, Robotics And AI Event In Vietnam

April 27, 2018 by 7 Comments

Blockchain Education Network Vietnam recently held an event titled “Building a Robotics & Artificial Intelligence Ecosystem with Blockchain”. The title alone has three of my favorite things in it, so when a client of mine asked me if I could put together a little hardware demonstration for the event, I jumped at the opportunity.

I also thought I’d take a moment to write about it, because I haven’t seen much coverage of emerging technology events in the developing world, and the fact is that there’s a consistently high level of interest. I’ve yet to go to an event that wasn’t filled to capacity, and I hope to share some of that enthusiasm with you.

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IR Detective Eases Development With Compact Decoding

April 27, 2018 by 13 Comments

Hardware development often involves working with things that can’t be directly perceived, which is one reason good development tools are so important. In appreciation of this, [David Johnson-Davies] created the IR Remote Control Detective to simplify working with IR signals. While IR remote controls are commonplace, there are a number of different protocols and encoding methods in use across different brands. The IR Detective takes care of all of that with three main components, none of which are particularly expensive. To use the decoder, one simply points an IR remote at the unit and presses one of the buttons. The IR Detective will identify the protocol, decode the signal, and display the address and command related to the key that was pressed. The unit doesn’t consist of much more than an ATtiny85 microcontroller, a small OLED display, and an IR receiver unit. The IR receiver used is intended for a 38 kHz carrier, but such receivers can and do respond to signals outside this frequency, although they do so at a reduced range.

As a result, not only is the unit useful for decoding IR or verifying that correct signals are being generated, but the small size and low cost means it could easily be used as a general purpose receiver to add IR remote control to other devices. It’s also halfway to bridging IR to something else, like this WiFi-IR bridge which not only interfaces to legacy hardware, but does it across WiFi to boot.

Circuit VR: Oscillating Bridges

April 27, 2018 by 21 Comments

Circuit VR is where we talk about a circuit and examine how it works in simulation with LT Spice. This time we are looking at a common low-frequency oscillator known as the Wien bridge oscillator.

What makes an oscillator oscillate? A circuit with amplification that gets the same amount of the output signal fed back into its input, in phase, will oscillate. This is the Barkhausen criterion. Here, we’re going to look into what makes an oscillator work in simulation, and gain some insight into what happens when there’s too much feedback and too little.

In particular, we’ll look at the Wien bridge oscillator, a very simple design that originated as a way to measure impedance back in 1891. Modern versions add some additional features, but let’s start with the most simple implementation and work our way up.

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Unlocking Drones With Go

April 27, 2018 by 14 Comments

Looking for a first project in a relatively new language that’ll stretch your abilities? [Ron] was, so he hacked a commercially available drone and opened up a lot of its functionality, while writing the client software in Go.

The drone is a DJI Tello, which has some impressive hardware like a 14-core Intel processor and excellent video processing abilities. There’s also a vibrant community and a lot of support, making it the ideal platform for a project like this. It communicates to a base station via WiFi, and using some tools like the Wireshark [Rob] was able to decipher a lot of the communications and create a whole new driver for the drone. While the drone can be controlled in the traditional way, users can also write programs to control the drone as well.

The project is both an impressive feat in reverse engineering an inexpensive drone, and a fun example of programming in the Go language. Because of the fun and excitement of drones, they have become a popular platform on which to hack, from increasing their range to becoming a platform for developing AI.

A Low Cost, Dead Tree Touch Screen

April 27, 2018 by 38 Comments

Remember the “paperless office”? Neither do we, because despite the hype of end-to-end digital documents, it never really happened. The workplace is still a death-trap for trees, and with good reason: paper is cheap, literally growing on trees, and it’s the quickest and easiest medium for universal communication and collaboration. Trouble is, once you’re done scribbling your notes on a legal pad or designing the Next Big Thing on a napkin, what do you do with it?

If you’re anything like us, the answer to that question is misplacing or destroying the paper before getting a chance to procrastinate transcribing it into some useful digital form. Wouldn’t paper that automatically digitizes what you draw or write on it be so much better? That’s where this low-cost touch-sensitive paper (PDF link) is headed, and it looks like it has a lot of promise. Carnegie-Mellon researchers [Chris Harrison] and [Yang Zhang] have come up with cheap and easy methods of applying conductive elements to sheets of ordinary paper, and importantly, the methods can scale well to the paper mill to take advantage of economies of scale at the point of production. Based on silk-screened conductive paints, the digitizer uses electrical field tomography to locate touches and quantify their pressure through a connected microcontroller. The video below shows a prototype in action.

Current cost is 30 cents a sheet, and if it can be made even cheaper, the potential applications range from interactive educational worksheets to IoT newspapers. And maybe if it gets really cheap, you can make a touch-sensitive paper airplane when you’re done with it.

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