New Part Day: Silent Stepper Motors

Some of the first popular printers that made it into homes and schools were Apple Imagewriters and other deafeningly slow dot matrix printers. Now there’s a laser printer in every office that’s whisper quiet, fast, and produces high-quality output that can’t be matched with dot matrix technology.

In case you haven’t noticed, 3D printers are very slow, very loud, and everyone is looking forward to the day when high-quality 3D objects can be printed in just a few minutes. We’re not at the point where truly silent stepper motors are possible just yet, but with the Trinamic TMC2100, we’re getting there.

Most of the stepper motors you’ll find in RepRaps and other 3D printers are based on the Allegro A498X series of stepper motor drivers, whether they’re on breakout boards like ‘The Pololu‘ or integrated on the control board like the RAMBO. The Trinamic TMC2100 is logic compatible with the A498X, but not pin compatible. For 99% of people, this isn’t an issue: the drivers usually come soldered to a breakout board.

There are a few features that make the Trinamic an interesting chip. The feature that’s getting the most publicity is a mode called stealthChop. When running a motor at medium or low speeds, the motor will be absolutely silent. Yes, this means stepper motor music will soon be a thing of the past.

However, this stealthChop mode drastically reduces the torque a motor can provide. 3D printers throw around relatively heavy axes fairly fast when printing, and this motor driver is only supposed to be used at low or medium velocities.

The spreadCycle feature of the TMC2100 is what you’ll want to use for 3D printers. This mode uses two ‘decay phases’ on each step of a motor to make a more efficient driver. Motors in 3D printers get hot sometimes, especially if they’re running fast. A more efficient driver reduces heat and hopefully leads to more reliable motor control.

In addition to a few new modes of operation, the TMC2100 has an extremely interesting feature: diagnostics. There are pins specifically dedicated as notification of shorted outputs, high temperatures, and undervolt conditions. This is something that can’t be found with the usual stepper drivers, and it would be great if a feature like this were to ever make its way into a 3D printer controller board. I’m sure I’m not alone in having a collection of fried Pololu drivers, and properly implementing these diagnostic pins in a controller board would have saved those drivers.

These drivers are a little hard to find right now, but Watterott has a few of them already assembled into a Pololu-compatible package. [Thomas Sanladerer] did a great teardown of these drivers, too. You can check out that video below.

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Audience Pong and RC Trash bins: An intro to TEI

This past weekend, I had the chance to visit this year’s Tangible, Embedded, and Embodied Interaction Conference (TEI) and catch up with a number of designers in the human-computer-interaction space. The conference brings together a unique collection of artists, computer scientists, industrial designers, and grad students to discuss computer interactivity in today’s world. Over the span of five days (two for workshops, and three for paper presentations), not only did I witness a number of today’s current models for computer interactivity (haptics, physical computing with sensors), I also witnessed a number of excellent projects: some developed just to prove a concept, others, to present a well-refined system or workflow. It’s hard to believe, but our computer mouse has sat beneath our fingertips since 1963; this conference is the first place I would start looking to find new ways of “mousing” with tomorrow’s technology.

Over the next few days, I’ll be shedding more light on a few projects from TEI. (Some have already seen the light of day.) For this first post, though, I decided to highlight two projects tied directly to the conference culture itself.

Before each lunch break, the audience was invited to take part in an audience-driven interactive game of “Collective” Pong. With some image processing running in the background, players held up pink cards to increase the height of their respective paddle–albeit by a miniscule amount. The audience member’s corresponding paddle weight was mapped to their respective marker location on the screen (left or right). It turns out that this trick is a respectful nod back to its original performance by [Loren Carpenter] at Siggraph in 1991. With each audience member performing their own visual servoing to bring the paddle to the right height, we were able to give the ball a good whack for 15 minutes while lunch was being prepared.

TEI_2015Cards

Next off, the conference’s interactivity spread far beyond the main conference room. During our lunch breaks we had the pleasure of discarding our scraps in a remotely operated trash bin. Happily accepting our refuse, this bin did a quick jiggle when users placed items inside. Upon closer inspection, a Roomba and Logitech camera gave it’s master a way of navigating the environment from inside some remote secret lair.

Overall, the conference was an excellent opportunity to explore the design space of tinkerers constantly re-imagining the idea of how we interact with today’s computers and data. Stay tuned for more upcoming projects on their way. If you’re curious for more details on the papers presented or layout of the conference, have a look at this year’s website.

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When Handmade Circuits Become Art

This mind boggling piece of art took hundreds of hours to make over a period of three years. The entire structure is composed of thousands of components, all of which are part of the clocks circuit. They call it, The Clock.

Each component was hand soldered in this ridiculously complex 3D structure. They have a typical artist statement, but you know what — for once it’s actually pretty intuitive.

“The Clock” has digital pulses flowing inside every single wire and every single part. These synchronized pulses, all intelligently controlled and channeled through every circuit, is a binary “dance” of hundreds of bits of information coming and going from one section to another. All working in unison to display the flow of time.

The clock works by taking in mains voltage and counting the frequency of pulses — in North America it’s 60Hz — conveniently a unit divisible for time. However if you were to take this clock elsewhere, perhaps where AC cycles at only 50Hz — the clock’s not going to keep accurate time.

It has no buttons — but you can change the time using a “Time Adjusting Magnet” over certain areas of the clock which feature micro electro-magnetic switches. The whole thing weighs about 14 pounds and consists of 1,916 individual components! Wow.

This has gotta be up there with some of our favorite clock builds we’ve ever seen on Hack a Day, perhaps with it only being second to this home-made Atomic Clock!

[Thanks Arthur!]

Trinket uses RF to track you through the house

If you carry a cell phone with GPS, you always know where you are on the planet. But what about inside buildings or even your own home? Knowing if you’re in the kitchen or the living room would be a great feature for home automation systems. Lights could come on as you enter the room and your music could follow you on the home audio system. This is exactly the what [Eric] is working on with his Radiolocation using a Pocket Size Transceiver project. [Eric] started this project as an entry in the Trinket Everyday Carry Contest. He didn’t make the top 3, but was one of the fierce competitors who made the competition very hard to judge!

The heart of the project is determining Time Of Flight (TOF) for a radio signal. Since radio waves move at the speed of light, this is no small feat for an Arduino based design! [Eric] isn’t re-inventing the wheel though – he’s basing his design on several research papers, which he’s linked to his project description. Time of flight calculations get easier to handle when calculating round trip times rather than one way. To handle this, one or more base stations send out pings, which are received and returned by small transponders worn by a user. By averaging over many round trip transmissions, a distance estimation can be calculated.

[Eric] used a Pro Trinket as his mobile transponder, while an Arduino Micro with it’s 16 bit counter acted as the base station. For RF, he used the popular  Nordic nRF24L01+ 2.4 GHz transceiver modules. Even with this simple hardware, he’s achieved great results. So far he can display distance between base and transponder on a graph. Not bad for a DIY transponder so small if fits in a 2xAAA battery case! [Eric’s] next task is working through multipath issues, and testing out multiple base stations.

Click past the break to see [Eric’s] project in action!

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Arduino + Servo + Scotch tape == An Interesting Conversation

If one could temporarily remove their sense of humor and cast a serious look into a Rube Goldberg machine, they would not say to themselves “well that looks simple.” Indeed, it would almost always be the case that one would find themselves asking “why all the complexity for such a simple task?”

Too often in hacking are we guilty of making things more complicated than they really need to be. Maybe it’s because we can see many different paths to a single destination. Maybe it’s because we want to explore a specific path, even though we know it might be a little harder to tread. Maybe it’s just because we can.

rubegoldberg

But imagine approaching a hack as simply a means to an end. Imagine if you did not have all of that knowledge in your head. All of those tools at your disposal. How would this change your approach? When [yavin427] decided to automate the leveling up process in his favorite video game, odds are he had never taken a game controller apart. Had never touched an oscilloscope. Indeed, he might have no knowledge of what a transistor or microcontroller even is. While many of our readers would have taken the more difficult path and tapped directly into the TTL of the controller to achieve maximum efficiency; it is most likely that [yavin427] would not have known how to do this, and thus would not have seen the many other paths to his end goal that would have been obvious to us. Yet he achieved his end goal. And he did it far easier and with less complication than many of us would have done.

Thoughts?

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Get Better at Mortal Kombat by Hacking Your PS3 Controller

Fighting games like Mortal Kombat provide you with a variety of different available moves. These include kicks, punches, grabs, etc. They also normally include various combination moves you can perform. These combo moves require you to press the proper buttons in the correct order and also require you to time the presses correctly. [Egzola] realized that he could just hack his controller to simulate the button presses for him. This bypasses the learning curve and allows him to perform more complicated combinations with just the press of a single button.

[Egzola] started by taking apart his Playstation 3 controller. There were two PCB’s inside connected by a ribbon cable. Luckily, each individual pad for this cable was labeled with the corresponding controller button. This made it extremely simple to hack the controller. [Egzola] soldered his own wires to each of these pads. Each wire is a different color. The wires then go to two different connectors to make them easier to hook up to a bread board.

Each wire is then broken out on the breadboard. The signal from each button is run through a 4n25 optoisolator. From there the signal makes its way back to various Arduino pins. The 4n25 chips keeps the controller circuit isolated from the Arduino’s electrical circuit. The Arduino also has two push buttons connected to it. These buttons are mounted to the PS3 controller.

Now when [Egzola] presses one of the buttons, the Arduino senses the button press and simulates pressing the various controller buttons in a pre-programmed order. The result is a devastating combination move that would normally require practice and repetition to remember. You might say that [Egzola] could have spent his time just learning the moves, but that wasn’t really the point was it? Check out the video below for a demonstration. Continue reading “Get Better at Mortal Kombat by Hacking Your PS3 Controller”

A Primer on Buck (and Boost) Converters

We all know that the reason the electrical system uses alternating current is because it’s easy to step the voltage up and down using a transformer, a feature which just isn’t possible with a DC system… or is it? Perhaps you’ve heard of mysterious DC-DC transformers before but never really wanted to look at the wizardry that makes them possible. Now, SparkFun Director of Engineering [Pete Dokter] has a tutorial which explains how these mysterious devices work.

Known as buck converters if they step the input voltage down and boost converters if they step the voltage up, [Pete] explains how these circuits exploit the properties of an inductor to resist changes in current flow. He goes into exquisite detail to explain how components like transistors or MOSFETs are used to switch the current flow to the inductor very rapidly, and just exactly what happens to the magnetic field which makes these devices possible.

The video gives a good amount of background knowledge if you’ve always wanted to understand these devices a little bit better. There are also a few projects floating around that exploit these devices, such as one that uses an AVR microcontroller to perform the switching for a small circuit, or another that uses the interesting properties of these circuits to follow the I-V curve of a solar panel to help charge a bank of batteries. The possibilities are endless!

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