For quite some time now we’ve seen people casting their own countertops and other surfaces out of cement. It’s a combination of mold-making and surface finishing that produces a smooth and durable surface at quite a low cost, if you don’t factor in damage done to your back when lifting the thing for installation.
This offering is a little bit different. [Elliott Spelman] built his own touch sensitive cement table top. When you place your grubby hands on the polished surface, a loop of neon lighting is switched on. This is thanks to a 4:1 mix of quick setting cement and iron oxide powder. Bare copper wire was laid around the edges of the surface to be encased by the cement for making connections later.
There were some sad moments when [Elliott] was removing the cast surface from the mold. He ended up cracking it and suggests others be liberal with their use of both wax on the mold before casting, and patience in removing the cement afterward. We might also suggest a strengthening agent like fiber reinforcement. The edges and surface can be sanded to the finish desired and in this case, attaching table legs was easy since the wooden underside of the mold remains on the bottom of the cement.
The neon lighting adds a retro touch to this build. It’s sad to see this technology dying away, so a resurgence of artisanal neon is great in our book. [Elliott] found a Bay Area arts collective called the Crucible which does a lot of art glass education to help him make two hoops of glass tube and fill them with the appropriate gasses. A capacitive touch sensor (once Atmel, now Microchip part) AT42QT2120 (datasheet) monitors the wire coming from the slab and switches the power supply for the tubes using a combination of relay board and Arduino Uno.
We find the prospect of positional sensing in doped cement fascinating. Anyone have ideas for adapting this technique so that a more long and narrow slab could have positional awareness within, say, a few inches? Let us know in the comments.
Continue reading “Touch Sensitive Cement with Just a Dash of Neon”
You don’t have to have high-quality parts to play around with electronics and here’s a great example. [Vishal] used junk to play around with CapSense, the touch sensitive Arduino library. What he ended up with is this touch-based piano keyboard.
We’ve featured the CapSense library in the past, but even that example uses a very meticulously crafted test rig of foil tape, protoboard, and some resistors. If you still haven’t given it a try follow this example of using aluminum foil, electrical tape, and a cardboard box.
[Vishal] just sandwiched the end of jumper wire between two pieces of foil to make each ‘key’. We believe the other end of the wire is soldered to the bias resistors where they connect to a couple of pin headers. The headers were hot-glued in place through holes in the bottom of the box, making the entire rig simple to plug into the Arduino board driving it. After adding in a small speaker and flashing the code he’s finished. It certainly makes for a short afternoon project which you won’t feel bad about taking apart later since you didn’t sink a ton of time or resources into the build.
A lot of people might turn their noses up at an electronic version of bagpipes. But we see a definite need for them. After all, it’s pretty hard to take your bagpipes on a road trip, but this eChanter will have no trouble entertaining your fellow travelers.
The musical instrument is Arduino-based and the builder can decide between a headphone jack (use it with that FM transmitter when in the car!) or a speaker. The version seen above uses headphones with a piece of PVC pipe as the body, screw heads as touch sensors, and a project box to hold the electronics. But there are a lot of alternatives suggested, such as using automatic sprinkler parts. It sounds like a riser, connector, and pop-up sprinkler head body will do just as well hosting all of the components.
Want to hear what it sounds like? There’s an mp3 clip under the final steps section.
We never thought about it before, but having the controls on the bottom of a clock is a bit of an inconvenience. [Alex Whittemore] mutes the LEDs on his clock each night and after a while, decided he should make the mute button into a touch strip on the case. You’ll remember that the Bulbdial clock uses colored LEDs to create the effect of a sun-dial, casting colored shadows for each hand of the clock. It makes sense that this would put off a pretty good amount of light at night. [Alex’s] original thought was to use a capacitive touch sensor but complexity and cost were in his way. What he ended up with is a resistive touch switch based off of two metal strips. He used metal repair tape but suggests copper foil as he was unable to solder to tape. When your finger touches the two strips it completes the circuit for the base of a transistor, which in turn grounds the mute button on the clock. Cheap, simple, and illustrated in the video after the break.
Continue reading “Making the Bulbdial clock touch sensitive”
[Viacheslav] built a keypad that uses human capacitance to detect key presses. Unlike normal keys which close a physical connection, his project detects touch through the PCB substrate. He uses the analog comparator of an AVR ATmega8 to detect the moment of zero crossing and then measures the time it takes to discharge in order to detect key presses.
Continue reading “Touch sensitive keypad”