Hypomnemata

The Volksduino is our high-power Arduino clone.  The first (short) run is nearly sold out, and has been integrated into everything from a prototype laser display to a bacon-y alarm clock.  Over the next week or two, we’ll have a series of blog posts talking about these Volksduino projects, with links as needed.

First up: the laser drive circuit, as a teaser.  This is a part of a Noisebridge project that’s still a bit nascent, but it’s handy to know how to drive a higher current device from the Volksduino board.  Miloh is hooking up his Volksduino to a laser diode, adding some repurposed hard drive platters, and building a raster scanning laser display.  Note that this is a Volksduino v1.0, which was used in the Greenwire (PCB Repair) workshop.

The laser pulls more current than the Atmega328 can provide, so he added a transistor and a couple of resistors to drive it.  The transistor is a 2N2222 or 2N3904, and the resistors look to be 510 ohms between digital 8 and the base of the transistor, and 22K into the collector, with the laser diode going from the emitter to ground.

With that, he can pulse the laser, and has full PWM control of it.  Along with an optical encoder on the mirror platters, this can form a full-fledged raster scanner.  I can’t wait to see the finished result here; perhaps it’ll be done soon enough to be featured in this parade of Volksduino projects!

Coming up next time: monitoring web server utilization with a Volksduino and a surprising choice of output devices.