Mechaduino- Closed Loop Stepper Servos For Everyone

Is it something in the water, or have there been a lot of really cool servo projects lately? Mechaduino is a board that sits on a regular stepper motor and turns it into a servo with a closed loop control of 0.1degree.

Whenever we post something about using cheap brushless motors for precision control, someone comments that a stepper is just a brushless motor with a lot of poles, why not just control it like one. That’s exactly what the Mechaduino does. They also hint at doing something very clever with a magnetic encoder on the board which allows them, after a calibration routine, to get the accuracy they’ve promised.

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Motorized Music Box Cranks Out Stairway to Heaven

[Bokononestly] found a lil’ music box that plays Stairway to Heaven and decided those were just the kinds of dulcet tones he’d like to wake up to every morning. To each his own; I once woke up to Blind Melon’s “No Rain” every day for about six months. [Bokononestly] is still in the middle of this alarm clock project right now. One day soon, it will use a *duino to keep track of the music box’s revolutions and limit the alarm sound to one cycle of the melody.

stairway-musicbox-alarm-clock[Bokononestly] decided to drive the crank of the music box with a geared DC motor from an electric screwdriver. After making some nice engineering drawings of the dimensions of both and mocking them up in CAD, he designed and printed a base plate to mount them on. A pair of custom pulleys mounted to the motor shaft and the crank arm transfer motion using the exact right rubber band for the job. You can’t discount the need for a big bag ‘o rubber bands.
In order to count the revolutions, he put a wire in the path of the metal music box crank and used the body of the box as a switch. Check out the build video after the break and watch him prove it with the continuity function of a multimeter. A clever function that should at some point be substituted out for a leaf switch.

We’ve covered a lot of cool clock builds over the years, including one or two that run Linux. And say what you will about Stairway; it’s better than waking up to repeated slaps in the face.

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iPad Control for Guitar Pedals

[gutbag] is a guitarist. And guitarists are notorious knob-twiddlers: they love their effects pedals. But when your music involves changing settings more than a few times in the middle of a song, it can get distracting. If only there were little robot hands that could turn the knobs (metaphorically, sorry) during the performance…

Tearing into his EHX Pitch Fork pedal, [gutbag] discovered that all of the external knob controls were being read by ADCs on the chip that did all of the processing. He replaced all of the controls with a DAC and some analog switches, coded up some MIDI logic in an ATmega328, and built himself a custom MIDI-controlled guitar pedal. Pretty slick, and he can now control it live with his iPad, or sequence the knobs with the rest of their MIDI system.


This wasn’t [gutbag]’s first foray into pedal automation, however. He’d previously automated a slew of his pedals that were already built to take control-voltage signals. What we like about this hack is the direct substitution of DAC for potentiometers. It’s just hackier. (Oh, and we’re envious of [gutbag]’s lab setup.)

This isn’t the first time we’ve covered [gutbag]’s band, Zaardvark, either. Way back in 2013, we featured an organ-pedal-to-MIDI hack of theirs. Keep on rockin’.

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Pong In Real Life, Mechanical Pong

[Daniel Perdomo] and two of his friends have been working on a mechanical version of Pong for the past two years. We can safely say that the final result is beautiful. It’s quite ethereal to watch the pixe–cube move back and forth on the surface.

[Daniel] has worked in computer graphics for advertising for more than 20 years. However, he notes that neither he nor his friends had any experience in mechanics or electronics when they began. Thankfully, the internet (and, presumably, sites like Hackaday) provided them with the information needed.

The pong paddles and and pixel (ball?) sit onto of a glass surface. The moving parts are constrained to the mechanics with magnets. Underneath is a construction not unlike an Etch A Sketch for moving the ball while the paddles are just on a rail with a belt. The whole assembly is made from V-groove extrusion.

Our favorite part of the build is the scroll wheel for moving the paddle back and forth. For a nice smooth movement with some mass behind it, what’s better than a hard-drive platter? They printed out an encoder wheel pattern and glued it to the surface. The electronics are all hand-made. The brains appear to be some of the larger Arduinos. The 8-bit segments, rainbow LEDs, etc were build using strips glued in place with what looks like copper foil tape connecting buses. This is definitely a labor of love.

It really must be seen to be understood. The movement is smooth, and our brains almost want to remove a dimension when watching it. As for the next steps? They are hoping to spin it up into an arcade machine business, and are looking for people with money and experience to help them take it from a one-off prototype to a product. Video after the break.

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DIY Air Quality Meter And Emissions Tester

Handheld measuring devices make great DIY projects. One can learn a lot about a sensor or sensor technology by just strapping it onto a spare development board together with an LCD for displaying the sensor output. [Richard’s] DIY air quality meter and emissions tester is such a project, except with the custom laser-cut enclosure and the large graphic LCD, his meter appears already quite professional.

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Learn Functional Reactive Programming on Your Arduino

Everyone loves learning a new programming language, right? Well, even if you don’t like it, you should do it anyway, because thinking about problems from different perspectives is great for the imagination.

Juniper is a functional reactive programming language for the Arduino platform. What that means is that you’ll be writing your code using anonymous functions, map/fold operations, recursion, and signals. It’s like taking the event-driven style that you should be programming in one step further; you write a=b+3 and when b changes, the compiler takes care of changing a automatically for you. (That’s the “reactive” part.)

functionalIf you’re used to the first-do-this-then-do-that style of Arduino (and most C/C++) programming, this is going to be mind expanding. But we do notice that a lot of microcontroller code looks for changes in the environment, and then acts (more or less asynchronously) on that data. At that level of abstraction, something like Juniper looks like a good fit.

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Shower Thoughts in Your Car

The subreddit for Shower Thoughts offers wisdom ranging from the profound to the mundane. For example: “Every time you cut a corner you make two more.” Apparently, [Harin] has a bit of an addiction to the subreddit. He’s been sniffing the CAN bus on his 2012 Hyundai Genesis and decided to display the top Shower Thought on his radio screen.

To manage the feat he used both a Raspberry Pi and an Arduino. Both devices had a MCP2515 to interface with two different CAN busses (one for the LCD display and the other for control messages which carries a lot of traffic.

The code is available on GitHub. There’s still work to do to make the message scroll, for example. [Harin] has other posts about sniffing the bus, like this one.

We’ve covered CAN bus quite a bit, including some non-automotive uses. We’ve even seen the CAN bus for model railroading.