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.

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[Alex] continues to delight us with his projects. His third-generation tiny Braitenberg vehicle, a light seeking robot, is a big improvement over its predecessor, the mini Braitenberg vehicle. He’s moved from an Arduino based design to using the AVR ATtiny25v, replaced the breadboard with a PCB, and reduced the parts count. We think it was a great idea to use shrink tubing to shield the back of the photo-resistors from ambient light. Don’t miss the video of these little guys chasing a flashlight beam after the break. Read the rest of this entry »

[vilxes91] sent in this cool little false-theremin (translated). Its a pretty simple circuit, that can fit in really small places. It isn’t a true theremen because it uses the amount of light coming in around the lid for the modulation. To play it, you turn it on and open it up, the more open the lid, the higher the pitch. You can see a video of it in action after the break.

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The NoiseAXE is a miniature synthesizer based on the Picaxe 08M microcontroller.  Its operating principle is fairly simple: a conductive stylus touches the leg of one of eight resistors to play one of eight notes, while a photoresistor controls the amount of modulation, creating a variable vibrato effect.  While the synthesizer’s output is rather limited (the NoiseAXE isn’t exactly a Yamaha DX7), it’s still a pretty cool little project; you could use its unique sounds to add that gritty analog touch to your next electro hit.  Check out the video clip below to see and hear it in action.

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The ThingamaKIT is an anthropomorphic analog synthesizer kit from Bleep Labs. Using “LEDacles”, photoresistors, knobs, and switches, it generates interesting high pitched vocalizations. Bleep Labs sent us a review unit and this article shares our experiences building and using the kit. We’ve also included a tutorial on making some hacks, modifications, and circuit bends to it. Skip to the end to see a video of our hacked kit in action.

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