The Kraakdoos — Musical Abuser Of An Ancient OpAmp

September 3, 2015 by Nava Whiteford 11 Comments

A friend from the newly founded Yeovil Hackerspace introduced me to a device known as “The Kraakdoos” or cracklebox.

The cracklebox is an early electronic instrument produced by STEIM in the 1970s. The instrument consists of a single PCB with a number of copper pads exposed on one side. The player touches the pads and the instrument emits… sounds which can perhaps best be described as squeeze and squeals.

While the cracklebox was original sold as a complete instrument, the device has been reverse engineered, and the schematic documented. What lies inside is quite fascinating.

The heart of the cracklebox is an ancient opamp, the LM709. The LM709 is the predecessor to the famous LM741. Unlike the 741 the 709 had no internal frequency compensation. Frequency compensation is used to intentionally limit the bandwidth of an opamp. As input frequency increases, the phase shift of the opamp also increases. This can result in undesirable oscillation, as the feedback network forms an unintentional phase-shift oscillator.

Most modern opamps have internal frequency compensation, but the 709 doesn’t. Let’s see how this is used in the cracklebox:

Rather than using the frequency compensation pins as intended the cracklebox just routes them out to pads. In fact the cracklebox routes almost all the pins on the opamp out to pads, including the inverting and non-inverting inputs. A single 1MOhm feedback resistor is used in a non-inverting configuration. However reports suggest the instrument can work without a feedback resistor at all!

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Mini Fridge Turned Gameboy Puts Hot Games On Ice

September 3, 2015 by Kevin Dady 12 Comments

The plain old white mini fridge, a staple of many dorm rooms could use a little decoration. The resemblance to a classic gameboy is not that hard to imagine with some novelty stickers, but [ModPurist] went the extra mile with his Cold Boy.

Making a mini fridge into a playable gameboy involves taking apart the door, once in a Raspberry Pi 2 is fitted in along with a second hand “square screen” LCD. The front of the door is cut for some custom wooden buttons, which are connected to tactile switches. Once everything is fit and finished the door is reassembled, so the fridge can resume its normal life keeping soda and hot dogs good and cold. [ModPurist] covered the progression of the hack in his work log.

While it’s a little low to the ground, it should be a hit at college parties where being on the floor is not unusual. Join us after the break for a demonstration video and get your game on. It is, of course, missing one thing. There needs to be some type of latch inside to secure the beverages until the Konami code is entered.

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How To Build Anything Using Delrin And A Laser Cutter

September 3, 2015 by Sonya Vasquez 58 Comments

Need a simple fab process to go from a humble vector graphic to a final part — in a matter of minutes? The CO₂ laser cutter might be the right choice. As these tools open themselves up to widespread use through hackerspaces, I decided to give Delrin some well-deserved time under the spotlight.

The laser cutter yet-again proves itself a formidable tool with the construction of GameCube-Bot V2

This guide is a brief collection of tips and techniques that I’ve either learned from others or discovered on my own over the last couple years working with laser-cut Delrin (a.k.a Acetal) for functional prototypes. I hope this guide serves you well as we keep exploring the limits of the material.

As a disclaimer, keep in mind that in no way are these techniques unique or limited to Delrin. Many are not only years old but also common practice in either engineering design or the local machine shop. This article simply highlights the techniques shown here that perform both repeatably and predictably with Delrin and a couple hand-tools, and I hope to share them with a growing audience of laser cutter enthusiasts.

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Hackaday Prize Worldwide: Washington DC

September 3, 2015 by Mike Szczys 4 Comments

Join us for a Meetup on Saturday, September 12th near Washington DC. The Hackaday Crew is headed out to the DC area a week from Saturday and we want to hang out with you. We’ll be hosting a meetup at Nova Labs hackerspace in Reston, Virgina which is on the Northwest side of DC.

We’ll get things rolling at 6pm on Saturday, September 12. The event includes a few lightning talks, some food and drink, and a lot of socializing. This is free to all but you do need to RSVP to let us know you’re coming. We want you to bring a hack to show off. We love to see what people are working on no matter the level of complexity or stage of completion.

This all started when [Anool Mahidharia] mentioned that he’d be at Nova Labs on September 11-13 to lead a KiCAD PCB design workshop. This 2.5 day boot-camp starts with installing the Open Source EDA software on your laptop and ends when you have a completed PCB design ready to be submitted to a board fab. There is a charge for the workshop and attendance is limited so if you’re interested in it you should sign up now. Our events page is a good collection of information on both events as well as directions to get to Nova Labs.

The workshop is being organized by our friend [Bob Coggeshall] who we first met (and interviewed about his work on the Linux ‘sudo’ command) back in 2014 at Bay Area Maker Faire. Since then, [Brian Benchoff] swung by and visited [Bob] to talk about his company Small Batch Assembly and to tour Nova Labs. He will be conducting his own surface mount soldering workshop, will speak about Design For Manufacturing, and will show his Pick and Place machine during the weekend.

It will be fun to visit with [Bob] and to meet everyone who can make it to the Saturday evening meetup. So far [Mike Szczys], [Brian Benchoff], and [Sophi Kravitz] are all planning to be there. [Anool Mahidharia] will of course be there since he’s leading the workshop. The following weekend [Anool] and [Brian] will both be headed to Philadelphia for the 2015 Open Hardware Summit for which Hackaday is a proud sponsor. [Matt Berggren] and [Amber Cunningham] will both be at OSH as well, talking all things Tindie.

Learn 3D Modeling In Your Browser

September 3, 2015 by Al Williams 41 Comments

If you have a 3D printer, it is a good bet you’ve at least seen or heard of Tinkercad. There’s pros and cons to doing your design in a Web browser, but Tinkercad is very easy to use and great for making simple objects. However, there are other 3D object designers you can use in your browser, too. Tinkercad is just the one that everyone seems to know about.

I won’t talk much about Tinkercad, but if you haven’t tried it, it is well worth a look. It has a simple system of drawing things and holes. When you merge holes with things you can make lots of shapes. The alignment tools are good, and since Autodesk acquired them (part of its 123d app suite), it isn’t likely they will go under any time soon (which, as you may remember, almost happened).

If you are designing some great new secret invention you may shy away from cloud-based design programs. But if you are printing out key chains with your coworker’s cat’s name on it, do you really care? Most of these cloud-based programs will work from any computer so you can quickly do a design in a coffee shop and then go home and print it.

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Being Picked Up By A Swarm Of Drones May Become Reality

September 3, 2015 by James Hobson 70 Comments

In case you haven’t seen it yet, this video has been taking the internet by storm. The YouTube user [Gasturbine101] has successfully taken flight in his home made multi-rotor flying machine.

It’s a massive array of high powered brushless motors with props, fifty-four in fact, all counter-rotating. It has a weight of 148kg (we assume this includes the inventor), and produces a maximum lift of 164kg. Apparently it’ll even last for about 10 minutes. The props are grouped into six, using Hobbyking stabilizers to balance the flight.

He calls it the Swarm.

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Why IoT Will Fail (and How To Save It)

September 3, 2015 by Al Williams 76 Comments

Buzzword technology has two possible fates: they fail and disappear or they succeed and disappear. Remember at one time “multimedia” and “networking” were buzzwords. They succeeded and now they’ve vanished into ubiquity. Of course, there are plenty of failed buzzwords (like telecosm) that you probably don’t even remember. They just vanished into obscurity.

Unless you’ve been living under the CNC mill in your local hackerspace, you’ve probably heard or read about the “Internet of Things” (IoT). Companies big and small have realized that getting in early on The Next Big Thing is good for share prices and, right now, IoT is where everyone is trying to make a play.

There’s two things I’d observe, though: First, IoT is far from new. Connecting embedded systems to the Internet is old hat (I even wrote a book called Embedded Internet Design way back in 2003). Second, the way it is going, IoT–in its current incarnation–is doomed.

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