The keyboard on [Marek’s] laptop stopped working. He didn’t want to buy a replacement so he decided to start using an external keyboard. But hauling around a full 104-key model is a bit of a pain so he decided to make himself a shorter keyboard. He basically chopped off the 10-key pad on the right side of the board. This had the unexpected consequence of removing the screws that hold the top and bottom of the case together so he ended up adding a few extra screws to shore it up. You may be wondering how the key matrix still works if a portion of it has been cut off. [Marek] used the simple trick of folding the extra part of the membrane over and covering the unused contacts with some tape.
If you try this you should consider getting rid of the directional arrows and editing keys as well. There must be a way to map those keys elsewhere. Perhaps the half-qwerty keyboard hack will give you some inspiration for that.
If you’re too frail to take the full impact of a paintball round let this tank serve as your surrogate. The camera perched on top of the platform feeds video back to the operator’s head-mounted display. Instead of using a joystick or other traditional controller, the user aims by looking around, with his or her head movements mimicked by the camera and barrel of the tank. It looks cooler than it sounds so jump with us after the break to see for yourself. If you’re playing against this thing, we’d recommend aiming for the camera lens.
Continue reading “Wearable controller for your paintball tank”
Here’s a great magnetic levitator build. [Scott Harden] dug up the link after seeing that awesome rotating globe this morning. This version hangs objects below an electromagnet but it has a sensor system to provide a constant distance between magnet and object even if the payloads are a different weight. This is done with a couple of infrared sensors. One acts as a reference detector, always viewing an IR LED in order to get a baseline measurement. That measurement is compared to a second detector mounted slightly lower. The circuit adjusts the electromagnetic field, making sure the object is always breaking the lower beam but never interrupting the reference beam. No microcontroller needed, this is handled with a couple of OpAmps. See it in action after the break.
Continue reading “Build your own magnetic levitator”
[Alexy Sha] has done this fantastic hack, where he modified a magnetic floating globe to be motorized and spin on a tilted axis. The original globe was simply levitating via a magnet mounted inside. Though you could spin it by hand, it wasn’t motorized, and actually floated completely vertically instead of being tilted.
[Alexy] wanted to take this idea further and make it automatically spin on a rotated axes. He built a rotation assembly that was basically a motor, hung off-center, attached at the center of the globe. He had to power it via a coil hidden in the base unit, so that it could remain light enough to float. He did a fantastic job and the final product seems like it is the true way it should have been sold.
Check out a video of it in action after the break. We actually like the spinning ring, when he’s testing it, just as much as the final spinning globe.
Continue reading “Floating globe, hacked to rotate”
This peculiar setup allows [Ben Krasnow] to control an alternating current device using one pin on a microcontroller. He’s experimenting with a power drill and has relocated the trigger circuitry that makes it spin. On that board he found a variable resistor combined with a capacitor which control a triac, actuating the speed of a drill. [Ben’s] solution works great and isolates the drill from the control circuitry. He replace the variable resistor with a cadmium sulfide photoresistor (basically a variable resistor whose resistance depends on the intensity of light). Pulse-width modulation is used to adjust the brightness of an LED shining on that photoresistor and thereby affect the speed of the drill. This is such as simple alteration to the drill we’d call it MacGyver-esque.
See a demonstration after the break.
Continue reading “Controlling an AC drill using one PWM connection”