Inexpensive Display Jumps To Life

January 13, 2018 by Bryan Cockfield 19 Comments

If you’ve ever been to a local fair or amusement park, chances are you’ve seen an illusion known as Pepper’s Ghost. To perform the illusion, essentially all that’s needed is a thin sheet of plastic or one-way mirror and a light source. Get it right, and you’ll have apparitions popping up in all kinds of interesting places. With just the right software, though, one of those places could be in your own 3D display.

Using just a tablet and a sheet of plastic rolled into a cone, a three-person team was able to create a 3D display using the Pepper’s Ghost illusion. Using special software that the team developed, an image is altered so that when it reflects off of the plastic cone the image appears as a 3D rendering of the original picture. The rendering is perspective-correct and offers a novel way to interact with a 3D model without needing expensive equipment or special glasses.

If you do have some fancy equipment sitting around, like a computer monitor and some plexiglass, similar 3D displays have been made which utilize similar effects. Right now the team that developed this one haven’t made their code open yet, but have promised to release it soon so that others can build their own displays.

Thanks to [bmsleight] for the tip!

Tricked-Out Tablet Becomes Workbench Tool

November 28, 2017 by Dan Maloney 23 Comments

The workbench of the typical electronics hobbyist today would probably be largely recognizable by Heathkit builders back in the 60s and 70s. But where the techs and tinkerers of yesteryear would have had a real dead-tree SAMS Photofact schematic spread out on the bench, today you’ll get more use out of a flat-screen display for data sheets and schematics, and this handy shop Frankentablet might be just the thing to build.

Tablets like the older Nexus 9 that [enginoor] used as the basis for this build have a little bit of a form-factor problem because unlike a laptop, a tablet isn’t very good at standing up on its own. To fix that, they found a suitable silicone skin for the Nexus, and with some silicone adhesive began bedazzling the back of the tablet. A bendy tripod intended for phones was added, and with the tablet able to stand on its own they maximized the USB port with a right angle adapter and a hub. Now the tablet has a USB drive, a mouse, and a keyboard, ready for perusing data sheets online. And hackers of a certain age will appreciate the eyeball-enhancing potential of the attached USB microscope.

[enginoor]’s bench tablet is great, but we’ve seen full-fledged bench PCs before too. Take your pick — wall mounted and floating, or built right into the workbench.

Thanks to [ccvi] for the tip.

Hybrid Interface Brings Touchscreen To Rigol Scope

November 3, 2017 by Dan Maloney 7 Comments

With pervasive smartphones and tablets, the touch interface is assumed for small LCD screens, and we’ve likely all poked and pinched at some screen, only to find it immune to our gestures. Manufacturers have noticed this and begun adding touch interfaces to instruments like digital oscilloscopes, but touch interfaces tend to be an upgrade feature. But thanks to this hybrid oscilloscope touchscreen interface, even the low-end scopes can get in on the action.

It only makes sense that [Matt Heinz] started with one of the most hackable scopes for this build, which was his Master’s thesis project. Using an Android tablet as an auxiliary interface, [Matt] is able to control most of the main functions of the scope remotely. Pinching and expanding gestures are interpreted as horizontal and vertical scaling, while dragging the displayed waveform changes its position and controls triggering. While it’s not a true touchscreen scope, the code is all open source, so can a true aftermarket Rigol touchscreen be far away?

Rigol hacks abound here — you can talk to them in Linux, increase the bandwidth, or just get a look at their guts.

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Huge Functionality, Small Package: A Custom Tablet, Raspberry Style

July 23, 2017 by James Hobson 35 Comments

As the adage goes, “if you want something done right, do it yourself.” Desirous of a tablet but preferring to eschew consumer models, [Stefan Vorkoetter] constructed his own compact and lightweight Raspberry Pi tablet, covering several extra miles in the process.

The tablet makes use of a Raspberry Pi 3 and the official touchscreen, with the final product marginally larger than the screen itself. Designed with a ‘slimmer the better’ profile in mind, [Vorkoetter] had to modify several components to fit this precept; most obvious of these are the removal of the Pi’s GPIO headers, USB, and Ethernet ports, and removing the USB power out port from the touchscreen controller board so the two could be mounted side-by-side.

An Adafruit PowerBoost 1000C handles charging the 6200 mAh battery — meaning up to six hours(!) of YouTube videos — via a micro USB, but only after [Vorkoetter] attached a pair of home-made heatsinks due to negligible air flow within the case. A modified USB audio adapter boosts the Pi’s audio capabilities, enabling the use of headphones, a mic, and a built-in speaker which is attached to the tablet’s back cover.

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Homemade Subaru Head Unit Is Hidden Masterpiece

February 20, 2017 by Anool Mahidharia 30 Comments

The Subaru BRZ (also produced for Toyota as the GT86) is a snappy sportster but [megahercas6]’s old US version had many navigation and entertainment system features which weren’t useful or wouldn’t work in his native Lithuania. He could have swapped out the built in screen for a large 4G Android tablet/phone, but there’s limited adventure in that. Instead, he went ahead and built his own homemade Navigation system by designing and integrating a whole bunch of hardware modules resulting in one “hack” of an upgrade.

The system is built around a Lenovo 4G phone-tablet running android and supporting GPS, GLONASS as well as the Chinese BeiDou satellite navigation systems. He removed the original daughter board handling the USB OTG connection on the tablet, and replaced it with his version so he could connect it to his external USB board via a flat ribbon cable. The USB board contains a Cypress 4-port USB hub. One port is used as the USB HID device to allow external buttons for system control — Power, Volume Up/Down, Fwd/Rev, Play/Pause, and Phone Answer/Hangup. The second port is used as a regular USB input to allow connecting external devices such as flash drives. The third one goes to a reversing camera while the fourth port goes to a USB DAC.

The USB DAC is another hardware board by itself and also includes a Bluetooth module which integrates his phone’s audio and control functions with the on-board system. There’s also an audio mixer which allows him to use the phone audio without having to miss out on the navigation prompts from the tablet. Both boards also contain several peripheral circuits such as amplifiers and DC power supplies. Audio to the speakers is routed through six LM3886 based power amplifier boards. And the GPS module receives its own special low-noise amplifier board to ensure extremely strong reception at all times. That’s a total of ten boards custom built for this project. He’s also managed to source all the original harness connectors so his system is literally a snap in replacement. The final assembly looks pretty dashing.

For some strange reason, the Lenovo tablet uses 4.35V as the ‘fully charged” value for its LiPo instead of the more common 4.20V, so even with the whole system connected to a hefty 12V lead acid battery from which he’s deriving the 4.20V charging voltage for the tablet, it still complains about “low battery” — and he’s looking for advice on how he can resolve that issue short of blowing up the LiPo by using the higher charge voltage. Besides that, he’s (obviously a kickass) hardware designer and a little bit rusty on the software and programming side of things, for which he’s looking for inputs from the community. His introductory video is almost 30 minutes long, but the shorter demo video after the break shows the system after installation in his car. He’s posted all of his Altium hardware source files on the project page, but until he shares PDF versions, it would be difficult for most of us to look at his work.

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Down The Rabbit Hole And Back Out Again: Serial Over Headphone Jack

October 21, 2016 by Elliot Williams 14 Comments

[ttsiodras] tells an epic tale of getting a custom Debian kernel installed on an Asus MemoPAD (ME103K) tablet. Skipping to the end of the saga, he discovers what looks like serial data coming out on the headphone jack when the system boots, but the signal was so distorted that he couldn’t simply interpret it. The solution turns out to be attaching a level-converter chip.

A level converter is a non-inverting amplifier, usually with a Schmitt trigger for immunity against noise. In this case, it acts like a “binarizer” — outputting a high voltage when the input rises above a threshold, and a low when it drops below. It’s the right part when you need to clean up a messy digital signal, and in this case works just fine because the capacitive distortion effects slow down both the leading and trailing edges of the signal, keeping the serial data’s timing intact.

That was the spoiler. If you want to read up on putting a custom Linux on an Android device, check out [ttsiodras]’s first post where he backs the machine up, and the second where he gets his custom kernel up and running. If you’re ever faced with an Android tablet that hasn’t been owned yet, or if you just have a DIY streak, this should help you get started.

Using the audio jack for serial is actually not uncommon, and discovering a serial terminal that listens at boot time is our favorite way to wedge a Linux OS into odd devices. So when you see a funny, distorted signal coming out at 115,200 baud, take a moment to clean its edges up and see what you’ve got.

Ask Hackaday: DIY Handwriting Recognition

October 12, 2016 by Elliot Williams 39 Comments

Computer handwriting recognition is very cool by itself, and it’s something that we’d like to incorporate into a project. So we went digging for hacker solutions, and along the way came up with an interesting bit of history and some great algorithms. We feel like we’ve got a good start on that front, but we’re stuck on the hardware tablet sensor itself. So in this Ask Hackaday, we’re going to make the case for why you could be using a tablet-like device for capturing user input or doing handwriting recognition, and then we’re going to ask if you know of any good DIY tablet designs to make it work.

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