[HankDavis] sent along this link to a video showing a tutorial on how to make touch sensors using a “darlington pair”. In the video we are taken through the idea and how we’re going to construct it. [Thad]explains in detail how this works in simple terms and illustrates it clearly. Unfortunately they don’t show an actual constructed system, but this is so simple you could toss it together quickly and see for yourself. This is a great lesson on how to get a simple touch sensor into your projects. This video appears to be one of a series of class visuals, and you can find several others on youtube under this account.
This touch screen relies on measurements from two range finders to track your finger as you press buttons. [James Alliban] put this together as his first Arduino project. We’re familiar with [James'] background because of his informative augmented reality business card. As the Arduino picks up data from the range finder it sends it to a Flash script that is running on the PC.
As we watched the video after the break a lot of questions came to mind. What kind of angle do these Ping sensors have? Will there be interference problems if they were placed perpendicular with each other? Would you get more accurate data if they were not both on the top of the screen? For now this is just a preliminary experiment, but we like the concept and may give it a try ourselves.
[Andrew Jenner] pulled off something amazing with this Physical Tone Matrix. He wanted to build a physical version of a flash applet he had seen. Two layers make up the main user interface. The top layer is a sheet of acrylic that acts as a touch interface and below there’s an LED matrix. [Andrew's] touch interface uses wires running throughout the acrylic as contacts which are polled via transistor pairs. As you can see in the video after the break it works well and we like the fact that there’s a tactile component (due to the bumpy wires) you don’t get when working with a touchscreen.
The 16×16 grid of LEDs on the bottom layer correspond to each ‘button’ on the touch matrix hand have some extra functions such as playing Conway’s Game of Life. This fantastic build still has a couple of kinks to work out, most notably the interference in the audio circuit, but we’re quite impressed at what he’s achieved quickly. Plus, this is more economical than a monome and larger than some of the monome clones we’ve seen.
This security system called G-spot requires that you touch a special place on the car prior to attempting to start it. This is pretty slick as it could be completely un-obvious and doesn’t require any special fobs or minor surgery. With the right placement, no one would ever notice that you had touched it.
“I’m wondering if the vast knowledge base of HackADay’ers out there might know of some way to turn almost any laptop into a touch screen of some kind. Actually, any surface.”
He has an older Wacom Tablet, and would like to be able to add resistive touch screen capabilities so that he isn’t forced to use the Wacom pen. Being an artist and part time hacker, he even summed up the question in a comic-style post.
The chill of autumn is upon us, and with it comes the awkward sport of trying to work touch-sensitive phones and gadgets with gloved fingers. One can try toughing it out with fingerless gloves, or we’ve seen some costly solutions in the forms of specialized gloves and capacitive-compatible styluses, but sometimes simple is best: all it takes is a few stitches of conductive thread in the fingertips.
Conductive thread is available from various sources; SparkFun Electronics comes naturally to mind, but most vendors carrying the LilyPad Arduino will stock a suitable thread as well. Don’t fret if you’ve never sewn before — just a few simple loops are required, and it doesn’t need to be especially tidy. In principle this should work for trackpads and capacitive mice as well, if you use those in the field. For multitouch devices, add a separate conductive bit to each fingertip.
[Humberto] from NerdKits is one of our favorite tipsters. We like how he can take a concept that seems so extremely complicated, in this case touch capacitance sensing, and present it in a clear and concise manner thats impossible to not love. As previously mentioned the most recent NerdKits hack is on touch capacitance; by using a resistor capacitor pair and some clever switch timing, anyone is able to detect the presence of a human limb. Now who’s going to be the first to adapt this concept further in their own hack?
[Agent420] brought up this touchpad and VFD hack in the comments on our capicitive sensor guide post. He had broken dell laptop from which he harvested the touchpad and an HP laserjet that contributed the VFD. Though the touchpad communicates using standard PS2 protocol, he wanted to use it with his Atmel 8535 AVR which required him to write some custom code. In the picture above, you can see the VFD displaying the coordinates of his finger. You can download his code as well as the spec sheets for the different pieces on the project thread.
