Day: February 21, 2016

BBC Micro:Bit Gets An App

February 21, 2016 by 10 Comments

It’s a small, cheap, British single board computer, and nobody can get hold of them. Another Raspberry Pi Zero story, you might think, but no, this is about the other small cheap and difficult to find British SBC, the BBC micro:bit. Samsung UK have produced an app for the micro:bit that allows owners to write code on their Android phones, and upload it to their micro:bit via Bluetooth.

The micro:bit story has played out with agonising slowness over the last year, but it seems that there may now be light at the end of the tunnel. The idea is a good one: give a small but very capable single board computer to every Year 7 (about 12 years old) child, and watch them learn something more useful about computers than how to use a Windows application. It has echoes of the BBC Micro 8-bit computer for schools sponsored by the UK government in the 1980s, and the hope is that it will help reproduce the same technical literacy enjoyed by 1980s kids.

The plan was for the youngsters to receive their boards last October but the project as been plagued by a series of delays and the latest estimate from January was that the boards would reach the kids after the school half-term. In other words within the next couple of weeks, depending on which part of the UK the school is located in.

We recently had a brief opportunity here at Hackaday to examine a micro:bit in the wild. It is a capable little board in its own right, being at heart an mbed, however the recommended web-based micro:bit IDE and compiler differs from the more usual mbed toolchain. One thing that caught our attention in the demo we were given was the micro:bit’s use of USB to deploy code; since schools lock down computer hardware to the n’th degree we were concerned that the micro:bits might not be visible on school USB ports. Easy Bluetooth deployment through the Samsung app promises to bypass that barrier, which can only be a good thing.

We’ve been watching the micro:bit story here at Hackaday from the start, most recently we noted the arrival of Python on the platform. If it has a formative influence on the generation of developers and engineers you’ll be hiring in the mid-2020s then we expect it to feature in many future stories.

 

Smart Sweatbands

February 21, 2016 by 32 Comments

If you’ve ever known anyone who has to monitor their blood glucose level, you know it is annoying to have to prick your finger with a lancet to draw blood for each measurement. A new sweatband that incorporates flexible electronics can measure glucose–as well as sodium, potassium, and lactate–from your sweat, without a painful pin prick.

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Retrotechtacular: Transmission Lines

February 21, 2016 by 13 Comments

This great old video (embedded below the break) from Tektronix in the mid-60s covers a topic that seems to confuse folks more than it should — transmission lines. We found it on Paul Carbone’s blog, a great site for aficionados of old analog scopes in its own right.

As with many of these older videos, the pacing is a bit slow by today’s standards, but the quality of the material eventually presented more than makes it worth the effort to reign in your ADHD. For a preview, you can skip to the end where they do a review of all the material.

They start off 5:31 with a pulse travelling down a wire pair, and take a very real-world approach to figuring out the characteristic impedance of the line: if the pulse was created by a battery of 9V, how much current is flowing? If the DC resistance of the wire is zero then there should be an infinite current by Ohm’s law, and that’s clearly not happening. This motivates the standard analysis where you break the wire down into distributed inductance and capacitance.

Of course they do the experiment where you inject a pulse into a long loop of coaxial cable and play around with the termination at the other end of the line. They also measure the velocity factor of the line. Our only gripe is that they don’t tap the line in different places to demonstrate standing waves. The good news is that we’ve got YouTube (and [w3aew]) for that.

If you’ve got 23 minutes to spare, and are curious about transmission lines or just enjoy the soothing voice of a trained radio announcer reading out values of various termination resistors, this old gem is just the ticket. Enjoy!

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Nixie Thermometer Destined For Custom PC Case

February 21, 2016 by 18 Comments

There’s no denying the retro appeal of the warm glow of a set of Nixies, and when a friend was looking for a unique touch for the case of his new liquid-cooled PC, [Luca] pitched in with this sweet Nixie thermometer.

From the look of [Luca]’s detailed blog entries, he’s been at this build since the New Year. He starts with a list of requirements, including the oddly specific need for a round PC board. For the thermometer, three Nixies are enlisted for the display, two for the temperature and one for the units. Everything was prototyped on perf board before committing to a PCB design, but even with careful planning, the Nixie sockets on the final PCB came out a tiny bit too close together. Luckily the tubes still fit, even if they are snuggled together some. And yes, the tube bases all include the hated RGB LEDs – hey, it’s what the customer wanted. The specs are for the colors to change at the touch of a button; we’d like to see a color gradient linked to the temperature – blue for “nice and cool”, red for “leave the room.” You can see the finished thermometer in action below the break.

The recent run of Nixie projects continues unabated, and this one has a nice look that’s sure to complement the finished case. We’ve asked [Luca] to keep us up-to-date on the project, so hopefully we’ll get a look at why a round PCB is needed. While we wait for that, check out an earlier Nixie thermometer build with a bar graph twist.

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Breathing New Life Into An Old Key

February 21, 2016 by 13 Comments

For most of us who have experimented with Morse code, the oldest key we are likely to have used will have been a piece of military surplus kit from the Second World War era. [Kyle Gabriel] however is a lucky man. His grandfather left him his key-on-board telegraph practice set, a vintage key and telegraph sounder arrangement used to learn Morse code in the days when the telegraph was king. Rather than keep the set merely as an heirloom, [Kyle] set about bringing it up to date by interfacing it to a Raspberry Pi and writing a Morse reader program.

Along the way [Kyle] had to contend with debouncing the switching signal from the key, considering an RC network before settling on a software debounce timer. He provides a brief synopsis of the mechanics of Morse decoding software, and a demonstration of the code in action which you can see in the video below the break.

[Kyle’s] decoding software, beatbybeat, is on GitHub. We can see it will be a useful tool for anyone interested in Morse, or who is writing their own Morse software.

Morse code has featured on these pages more than a few times over the years. Of relevance to this piece are an Arduino decoding Morse code, a more up-to-date practice oscillator with a home-made key, and a couple of other vintage telegraphs reading RSS feeds and reading emails.

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