Rotary Wall Plug from Scrap

Rotary tools such as a Dremel are useful to have around for all sorts of tasks in a workshop, including cutting, polishing, and grinding. [Konstantin] sent us in his home made wall mount rotary tool based off of parts from a blender and an old bench top jigsaw. Unlike a Dremel where the motor is in the hand held part of the tool, this setup hides the blender motor (which provides the power) behind a wall panel, and is controlled via the blender’s speed settings buttons. We could see this configuration allowing for more delicate work due to the reduction of weight in hand, as well as the added bonus of a near impossibility of losing this tool. Overall an excellent re-purposing of leftover parts, be sure to check out [Konstantin]‘s blog for more build info and photos.

Rotary display uses VCR head and LEDs

[Daniel Daigle] is developing a rotary display that uses persistence of vision to graph data. The hardware he used includes a spinning head from a VCR, some LEDs, and a timing circuit to display 360 degrees of data. His timing input uses a waveform so this will work with any application where you can generate a PWM signal.

Check out his videos after the break that demonstrate a graph with a single line and another with six display lines.

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Lower productivity by using a rotary num pad

[Maximilian Ernestus] sent us a quick little demo that shows him using a rotary phone dial as a num pad. We’re often frustrated when notebooks and netbooks prohibit us from using our mad 10-key skills (alternate key mapping doesn’t count). This makes coding and using GnuCash undesirable on small form factor portables.

Instead of fixing the problem, [Maximilian] made it worse by interfacing a rotary phone as a num pad. An Arduino counts the pulses and feeds them to the computer via a serial connection.  From there it’s just a bit of software handling to issue a keypress.  He mentions that a future version should register as a USB keyboard. This is a great opportunity to ditch the Arduino and use the V-USB library.

Want to dig a bit deeper into this old technology? Don’t miss out on the information available from the Magic Phone hack.

Rotary encoding with your soundcard

[Stefan] sent in this project writeup to show us how he used a stepper motor as a rotary encoder. Using a stepper motor as an encoder isn’t really that new, as [Stefan] points out, we’ve seen it several times before. He wanted to use this in the quickest simplest way with his computer though. Instead of doing any decoding on a separate microprocessor, he’s connected the stepper directly to his sound card and written code to do the rest. You can download that code and see a video of some practical applications on his site.

Interfacing a digital rotary switch


[hw640] has put together a well written and detail packed explanation of how to interface with a digital rotary switch. These digital opto encoders have just two outputs with four possible logic levels (00, 10, 11, 01). The relative position of the switch is insignificant but the direction of rotation is what matters.

The short and dirty: Each of the switch’s 2 output pins is attached to a pin change interrupt on the microcontroller. Every time the switch moves it generates either a rising edge or a falling edge on one of the two pins; both edges cause an interrupt. By checking which pin caused the interrupt, then comparing the logic levels of the two pins after that interrupt, we can determine the direction the switch was rotated.

Although this explanation uses a PIC and code written in PicBasic Pro the concepts are discussed in the abstract and would easily be adapted to an AVR or another microcontroller of your choice.

HDDJ: hard drive as rotary input


[nvillar] wanted a relatively cheap way to make a rotary input device for audio mixing. After looking at several options including turn tables and professional audio scrubbers, they decided on the hard drive due to its size, price, and the feel of the disk. The geek factor of using a hard drive as an input device probably didn’t hurt either. They provide schematics and details on how to make it all work. There’s a video after the break of the unit sending signals to a computer. No performances though, sorry.

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