This TARDIS Is Bigger On The Inside

A few months ago, YouTube user [Maladroit Modeller] uploaded a video of his model TARDIS from Doctor Who which shows an inside that’s bigger than the outside. Recently, [Maladroit Modeller] posted some pictures and has now uploaded a video showing how it’s done.

The TARDIS model itself is a 3:75 scale “Spin & Fly” model. The case to show everything off is built from foam core and the interior is built from foam core, silver paper, cardboard, styrene and other bits and pieces. There looks like there’s some EL wire being used, too, along with a lot of LEDs.

The build looks great and the illusion works very nicely in the video. Check out the video after the break, and then check out the “how it’s done” video for an explanation. Continue reading “This TARDIS Is Bigger On The Inside”

Make An Electric Skateboard For Your Cat

Have you ever looked at your cat and thought “You know, my kitten really needs an electric skateboard!” Probably not, but this seems to have happened to [Kim Pimmel] while looking at his cat MIDI, so he decided to build one. This process involved building a simple, low powered skateboard with a Feather mainboard and motor controller combined with a laser-cut switch mechanism. When [Kim] puts a treat into the mechanism, the cat pulls the switch and the skateboard moves forward, moving into a brave new e-skateboarding feline future. MIDI looks somewhat unimpressed by this whole business, but I suspect that as long as the treats keep coming, he will be happy to keep on truckin’. Now, if he can just figure out how to persuade the cat to ollie, we will be really getting somewhere.

Feline tomfoolery seems to be a regular pastime here on these pages, and more than just a quest for easy moggy-driven clickbait. A lot of cat feeders and cat finders abound, but this project isn’t the only cat-operated one. Our readers’ pets can probably spot an Arduino a mile away by now.

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The Un-Economy Of Building Your Own Spot Welder

If there’s one thing that brings hackers together, it’s the ability to build something for less money than it takes to buy it. It’s an exercise [Great Scott Gadgets] put to the test because he was playing around with some 18650 lithium cells, and had a huge need to put some tabs on batteries. This can be done by soldering, but to do it right you should really use a spot welder. Here’s the rub: you can buy a spot welder for about $250, and you can build one for a little less. So, the question: should [Great Scott] build or buy a spot welder? This wouldn’t be worth reading if he started off with an eBay order.

[Great Scott] designed this spot welder around a half-dozen supercaps, all securely held together with Kapton tape. This goes through a set of MOSFETs, and everything is controlled through an Arduino, a rotary encoder, and a dirt-cheap OLED display. It’s a simple enough circuit but a bit too much for perfboard, so [Great Scott] laid out a PCB and got a few boards for under $40. A bit of solder and some debugging later, and theoretically a spot welder was created.

After all that work, how did the spot welder work? Well, it didn’t. A slight misstep in the schematic meant this board didn’t have reference ground on the MOSFETs, so all this work was for naught. Of course, the only thing required to fix this board was a second board spin, as [Great Scott] probably bought more parts than necessary because that’s what smart people do. Still, he decided to cut his losses and shelve the project.

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Building A Pocket Sized Arduino Oscilloscope

There’s little question that an oscilloscope is pretty much a must-have piece of equipment for the electronics hacker. It’s a critical piece of gear for reverse engineering devices and protocols, and luckily for us they’re as cheap as they’ve ever been. Even a fairly feature rich four channel scope such as the Rigol DS1054Z only costs about as much as a mid-range smartphone. But if that’s still a little too rich for your taste, and you’re willing to skimp on the features a bit, you can get a functional digital oscilloscope for little more than pocket change.

While there are a number of very cheap pocket digital storage oscilloscopes (DSOs) on the market, [Peter Balch] decided he’d rather spin up his own version using off-the-shelf components. Not only was it an excuse to deep dive on some interesting engineering challenges, but it ended up bringing the price even lower than turn-key models. Consisting of little more than an Arduino Nano and a OLED display, the cost comes out to less than $10 USD for a decent DSO that’s about the size of a matchbox.

But not a great one. [Peter] is very upfront about the limitations of this DIY pocket scope: it can’t hit very high sample rates, and the display isn’t really big enough to convey anything more than the basics. But if you’re doing some quick and dirty diagnostics in the field, that might be all you need. Especially since there’s a good chance you can build the thing out of parts from the junk bin.

Even if you’re not looking to build your own version of the Arduino-powered scope [Peter] describes, his write-up is still full of fascinating details and theory. He explains how his software approach is to disable all interrupts, and put the microcontroller into a tight polling loop to read data from the ADC as quickly as possible. It took some experimentation to find the proper prescaler value for the Atmega’s 16MHz clock, but in the end found he could get a usable (if somewhat noisy) output with a 1uS sample rate.

Unfortunately, the Arduino’s ADC leaves something to be desired in terms of input range. But with the addition of an LM358 dual op-amp, the Arduino scope gains some amplification so it can pick up signals down into the mV range. For completion’s sake, [Peter] included some useful features in the device’s firmware, such as a frequency counter, square wave signal source, and even a voltmeter. With the addition of a 3D printed case, this little gadget could be very handy to have in your mobile tool kit.

If you’d rather go the commercial route, Hackaday’s very own [Jenny List] has been reviewing a number of very affordable models such as the DSO Nano 3 and the JYE Tech DSO150 build-it-yourself kit.

[Thanks to BaldPower for the tip.]

The Diaphragm is the Coil in These Flexible PCB Speakers

Speakers used to be largish electromechanical affairs, with magnets, moving coils, and paper cones all working together to move air around in a pleasing way. They’ve gotten much smaller, of course, small enough to screw directly into your ears or live inside the slimmest of smartphones and still delivery reasonable sound quality. The basic mechanism hasn’t changed much, but that doesn’t mean there aren’t other ways to make transduce electrical signals into acoustic waves.

Take these speakers made from flexible printed circuit boards, for instance. While working on his flexible PCB soft actuators, [Carl Bugeja] noticed that the PWM signals coursing through the coils on the thin PCB material while they were positioned over a magnet made an audible beeping. He decided to capitalize on that and try to make a decent speaker from the PCBs. An early prototype hooked to a simple amplifier showed promise, so he 3D-printed a ring to support the PCB like a diaphragm over a small neodymium magnet. The sound quality was decent, but the volume was low, so [Carl] experimented with a paper cone attached to the PCB to crank it up a bit. That didn’t help much, but common objects acting as resonators seemed to work fairly well. Check out the results in the video below.

This is very much a work in progress, but given [Carl]’s record with PCB creations from robotic fish to stepper motors built right into the PCB, we’d say he’ll make substantial improvements. Follow his and others’ progress in the Musical Instruments Challenge part of the 2018 Hackaday Prize.

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Easy GUI Front Ends for Arduino, Rasberry Pi, and More with MyOpenLab

If you want to integrate a nice graphical interface with a microcontroller or single-board computer for a useful piece of custom equipment, how will you go about it? MyOpenLab is a platform that makes it easy to design virtual interfaces your electronic builds. If you want controls and readouts for Arduino, Raspberry Pi, Android, or anything with a serial port, this is worth a try.

MyOpenLab reminds me of LabView. Not so much modern LabView with all of its add-ons and extras, but LabView back when it did just a few things but did them really well. The open source MyOpenLab project has been around for a while. The website and documentation are not in English, which may have kept some people from giving it a try, but the software itself is available in German, English, and Spanish. I took the plunge and found the language barrier didn’t cause me trouble.

As an example of what you can do, image you want to build a custom bench tool. You build virtual device (they call it a “VirtualMachine”) that uses your computer as the control panel and readout, and your electronic project as the physical interface. In myOpenLab your device will consist of two parts: a diagram and a front panel. Some things only live on the diagram, like a timer or a connection to an Arduino. But some things live on both like switches, LEDs, graphs, and so on. You can connect all the little boxes together to build up applications. They can stand alone, but the power comes in being able to connect to an Arduino or Raspberry Pi (or a few other options) for I/O.

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Convince Your Boss to Send You To Supercon

The Hackaday Superconference is rapidly approaching and you need to be there. The good news is, if you play your cards right you can get your boss to sign off on sending you to Supercon as part of your professional development.

This is the Ultimate Hardware Conference. This is your chance to recharge your batteries and come back energized for an amazing year ahead. You’ll be among hundreds of people who love to push the boundaries of what is possible. Dozens of talks and workshops take place over the backdrop of three days worth of a Hacker Village atmosphere focusing on a badge hacking demoscene.

We’re here to help you get to yes with the powers that be in your company. If you have a tight set of requirements that dictate what counts as professional development, we have a template to use in formulating your ask. Fill in this letter with the details that work for you and head over to the corner office with this in hand.

If you already have a supervisor who understands the hacker lifestyle, the best route is to show off the best Supercon has to offer. Share the playlist of talks from 2017 with them and you’re a shoe-in for your company’s conference attendance budget. And while you’re at it, try to convince your boss to come along for the fun!

See you in November!

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