Touch-A-Sketch Gives an Old Toy a New Twist

After nearly 60 years and a lot of stairs and squares, there is finally an easier way to draw on an Etch A Sketch®. For their final project in embedded microcontroller class, [Serena, Francis, and Alejandro] implemented a motor-driven solution that takes input from a touch screen.

Curves are a breeze to draw with a stylus instead of joysticks, but it’s still a 2-D plotter and must be treated as such. The Touch-A-Sketch system relies on the toy’s stylus starting in the lower left hand corner, so all masterpieces must begin at (0,0) on the knobs and the touch screen.

The BOM for this project is minimal. A PIC32 collects the input coordinates from the touch screen and sends them to a pair of stepper motors attached to the toy’s knobs. Each motor is driven by a Darlington array that quickly required a homemade heat sink, so there’s even a hack within the hack. The team was unable to source couplers that could deal with the discrepancy between the motor and knob shaft sizes, so they ended up mounting the motors in a small plywood table and attaching them to the stock knobs with Velcro. This worked out for the better, since the Etch A Sketch® screen still has to be reset the old-fashioned way.

They also considered using belts to drive the knobs like this clock we saw a few years ago, but they wanted to circumvent slippage. Pour another glass of your aunt’s high-octane eggnog and watch Touch-A-Sketch draw something festive after the break.

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Hacking An Industrial 42″ Multitouch PC

We’re slowly moving in the direction where everyone will have a touch screen desk like in the 1982 TRON movie or in the 1987 Star Trek: The Next Generation series with its ubiquitous touchscreen starship controls. [FFcossag] lucked into that future when a local company offered him an industrial 42″ multitouch PC that they were throwing out. A few hacks later and he has us all suitably envious.

Before hacking away though, he had to take care of some magic smoke. The source of this turned out to be yellow goop on the PC’s power supply that had turned conductive across a resistor. Cleaning it fixed the problem.

Moving on to the hacks, he added brightness control by using a potentiometer to control the power to the backlight. Be sure to watch carefully in the video below where he’s attaching a magnet and cord to the potentiometer, and encasing it all in epoxy. At that point, we’re pretty sure we see him spin up a hard drive platter with a sandpaper disk attached to it, forming a bench top disc sander and making us like this hack even more.

He also replaced a small speaker with a larger speaker and amplifier, giving a volume and sound quality difference that’s like night and day. He also added a breakout board with relays for power management, eliminating a seven watt continuous draw when in standby mode.

Be sure to watch the video to the end where he leaves us with a tour of the hacked interior hardware. We like how he’s labeled all his handiwork for any future hacker who might open it up

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Password-Free Guest WiFi from Raspberry Pi

Anytime you’re having more than a handful of people over to your place for a wild rager or LAN party (or both), you’ll generally need a way to make sure everyone can get their devices on the network. Normally, this would involve either putting your WiFi password into more phones than you can count or yelling your password across a crowded room. Neither of these options suited [NicoHood] and his partner, however, so he came up with another more secure solution to the WiFi-in-a-crowded-room problem.

He calls his project “guestwlan” and it’s set up to run on a Raspberry Pi with a touch screen. When a potential WiFi user approaches the Pi and requests access to the network, the Pi displays a QR code. Within that code is all of the information that the prospective device needs to connect to the network. For those who have already spotted the new security vulnerability that this creates, [NicoHood] has his guest WiFi on a separate local network just to make sure that even if someone nefarious can access the Internet, it would be more difficult for them to do anything damaging to his local network. As it stands, though, it’s a lot more secure than some other WiFi networks we’ve seen.

[NicoHood] also released his software on Git but it has been configured for use with Arch. He says that it would probably work in a Debian environment (which the Raspberry Pi-specific OS is based on) but this is currently untested. Feel free to give it a try and let us know how it goes.

Biometric Bracelet Electrifies You to Unlock Your Tablet

Researchers [Christian Holz] and [Marius Knaust] have come up with a cool new way to authenticate you to virtually any touchscreen device. This clever idea couples a biometric sensor and low-data-rate transmitter in a wearable wrist strap that talks to the touch screen by electrifying you.

Specifically the strap has electrodes that couple a 50V, 150kHz signal through your finger, to the touchscreen. The touchscreen picks up both your finger’s location through normal capacitive-sensing methods and the background signal that’s transmitted by the “watch”. This background signal is modulated on and off, transmitting your biometric data.

The biometric data itself is the impedance through your wrist from one electrode to another. With multiple electrodes encircling your wrist, they end up with something like a CAT scan of your wrist’s resistance. Apparently this is unique enough to be used as a biometric identifier. (We’re surprised.)

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Ditch the iPad; Build a Commodore 64 Tablet

The classic Commodore 64 has had its share of modernizing in the OS department. From its roots starting up a basic prompt, to full high resolution GUI packages like GEOS, to today where [Jim_64] added a tablet like launcher complete with a touch screen interface.

The GUI itself takes advantage of the high resolution graphics of the C-64 that looks similar to iOS, Icons are selected via cursor keys or joystick (what? no light pen?) and launch the various functions they represent. To add to the tablet-like feel of the OS, an off the shelf 3m touch screen panel and its corresponding RS232 interface board were obtained from digikey.

With the panel securely attached to the monitor, XY data from the various finger pokes are sent via serial at a blazing 1200 bps where the program interprets the position. Using the available demo (download sideA and sideB) and off the shelf parts, this should be easy for anyone with a classic C-64 to set up in their own home and have some fun.

Join us after the break for a few demo videos!

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Raspberry Pi Tablet Based on Sailfish OS

There are so many hacks in this project it’s hard to know where to start. So let’s start at the SailPi tablet which is a Raspberry Pi running the Sailfish OS on an LCD touch screen powered by a cell phone battery pack. The design looks more like a high-tech sandwich with the Pi in the middle than a tablet. Despite the appearance it works, at that’s what counts. COs98UBWsAAQNh5The creator, [Aleksi Suomalainen] expended a lot of effort pulling all the pieces together on this project.

The Sailfish OS project is targeted at creating a new OS for mobile devices, especially cell phones. It is open source which invites developers to contribute to the project. The touch screen user interface is designed for ease of use by gestures from one finger on the hand holding the phone.

[Aleksi] ported Sailfish to a Pi 2 during a hacking week. He’s shared the code for it on his blog. During the hack week he played with accessing the GPIO on the Pi to flash an LED. To get you up and running quickly he provided an image you can load onto an SD.

It appears the Pi is finding a niche for OS hackers in addition to the hardware hackers using the GPIO.

Don’t miss the demo after the break to see the OS running on the Pi. Continue reading “Raspberry Pi Tablet Based on Sailfish OS”


[Will] had a few reasons for turning a toaster oven into a reflow oven – he needed a project for an ECE lab, the lab’s current reflow oven was terrible, and the man is trying to keep [Will] down by not allowing toaster ovens in dorm rooms. What was born out of necessity actually turned into a great project – a reflow oven with touchscreen controls.

The toaster oven used for this build is a model [Will] picked up at Sears. It’s actually pretty unique, advertised as a ‘digital toaster’. This isn’t marketing speak – there’s actually a thermistor in there, and the stock toaster is closed loop. After disassembling the toaster and getting rid of the guts, [Will] whipped up a PCB for a Teensy 3.1 and the Adafruit capacative touch shield.

With the Teensy and touch screen, [Will] came up with an interface that looks ten times better than anything you would find on a Chinese auction site. It’s a great build, and since it’s kept in the electronics lab, will certainly see a lot of use.