Intro To DC Motor Control Using The SN754410

July 21, 2011 by Mike Szczys 10 Comments

So your electronic hobby skills are coming along quite nicely but you’re not very comfortable doing more than blinking a few LEDs. Now’s a good time to try something new by driving a couple of DC motors.

You probably know that you can’t just hook these up to the pins of your favorite uC and call it good. The motors draw a lot of current (especially if they’re strained in lifting a heavy load) which would burn out your logic circuitry. Add to this the excess induced current that is generated when a spinning motor is shut off and you’re going to need a control system that can handle these dangers.

Enter the h-bridge motor driver. [Chris] has guided us through the process of building and using a H-bridge in the past. This time he’s using a motor controller that has four half H-bridges built into it. He hooks up the SN754410 to two motors, giving him speed and direction control for both based on the duty cycle of a PWM signal entering the chip for less than $2.50. Check out the video after the break for an overview of his methodology, then work your way through the multi-page post that he recently published.

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Amazing Pipe Organ Desk Features Secret Compartments And An All-wood Logic Board

July 20, 2011 by Mike Nathan 38 Comments

wood_organ_desk_with_secret_compartment

Feeling pretty good after putting together your brand new standing computer desk? Step aside please, [Kagen Schaefer] has something he’d like to show you.

His Pipe Organ Desk is undoubtedly one of the coolest pieces of furniture we have seen in a long time. The project took [Kagen] over three years to complete, which sounds about right once you see how much attention was put into every last detail.

This desk is amazing in several ways. First off, the entire desk was constructed solely from wood. The drawers, the supports, knobs, screws, and even the air valves – all wood. Secondly, when one of the desk’s drawers are pushed in, air is directed to the organ pipes at the front of the desk, which plays a note.

A small portion of the air is also directed into the desk’s pneumatic logic board, which keeps track of each note that has been played. When someone manages to play the correct tune, a secret compartment is unlocked. The pneumatic logic board is an unbelievable creation, consisting of well over 100 wooden screws which can be tuned to recognize any number of “secret tunes”.

Sure a well-placed axe can open the compartment too, but who would destroy such a fine piece of work?

[via Make]

Chilean Teen Builds Automatic Earthquake Alarm

July 19, 2011 by Mike Nathan 27 Comments

When an earthquake is about to strike in Chile, who do you think is first to sound the alarm? You might be surprised that it’s not the government, but rather a 14 year old boy.

After living through an earthquake in 2010 and seeing the devastation this spring in Japan, Chilean teenager [Sebastian Alegria] decided that he wanted to construct something similar to Japan’s earthquake warning system. He purchased an off the shelf earthquake detector for less than $100, and connected it to his computer via an Arduino.

Now, whenever seismic activity is detected, his sensor tweets an alert letting his 29,000+ followers know that a perceptible earthquake is 5 to 30 seconds away. Apparently the Chilean government is working on a similar system that is still at least a year away, so in the meantime his fellow citizens rely on [Sebastian] instead.

While it might seem like a relatively easy hack to pull off compared to other earthquake detectors, we’re impressed by [Sebastian’s] creativity, and his will to help others. He’s been pounding away at computers since he was about 4 years old and has several other popular Twitter-based projects under his belt already, so we won’t be surprised if we hear from him again in the future.

One Really Big Quadcopter That Is Following In The Steps Of The Spruce Goose

July 19, 2011 by Mike Szczys 39 Comments

Behold the Land-Bear-Shark, a quadcopter on a rather grand scale. At a full eight kilograms it’s an easy target to compare the [Howard Hughes] behemoth, but in addition to the weight, this still has yet to make its first flight.

To give you some scale to the image above, the board at the center is an Arduino. It controls the beast, along with the help of a SparkFun IMU board which rides atop. Really, if any quadcopter of this size has a chance of working, this should be the one. The construction is beautiful, making use of carbon fiber rod along with 3D-printed connectors to assemble the frame. A lot of thought has gone into small things like conserving weight used on the landing gear, which are incorporated into the bottom corner brackets. The batteries are connected in a manner that makes them easy to adjust, acting as ballast for balancing the craft.

We’re keeping our fingers crossed that this will be more than the tongue-in-cheek title of the post which calls it a Quadrotor-shaped sculpture.

[via Adafruit]

Gambiologia – Brazilian Physical Item Hacking

July 19, 2011 by Jeremy Cook 13 Comments

Gambiologia, according to the source article, is the “science of Gambiarra.” For those not from Brazil, Gambiarra is “a Brazilian cultural practice of solving problems creatively in alternative ways with low cost and lots of spontaneity.” In other words, the hacking of real-world items. Gambiarra also has a connection to recycling, as instead of throwing something used out, it becomes something else new.

Although hacking may not be thought of as art in the traditional sense, [Fred Paulino] aims to change this with his exhibition of 20 Brazilian and international artists. A “Gambiologist” himself, he’s put together quite a collection of hacks and mods for the world to see. From computer monitors with eyes displayed on them, to a toilet held open with a two-by-four, his exhibit seems to cover a wide range of physical hacks, or Gambiarra.

Be sure to check out the article, as many of the hacks are quite clever or unusual (even if some may seem a bit unsafe). For more examples of hacking items into something new, check out this drill made out of a pencil sharpener or this remote control camera trigger using air freshener parts.

DIY Book Scanner Processes 600 Pages/hour

July 18, 2011 by Brian Benchoff 39 Comments

Like any learned individual, [Justin] has a whole mess of books. Not being tied to the dead-tree format of bound paper, and with e-readers popping up everywhere, he decided to build a low-cost book scanner so an entire library can be carried in a his pocket. If that’s not enough, there’s also a complementary book image processor to assemble the individual pictures into a paginated tome.

The build is pretty simple – just a little bit of black craft board for the camera mount and adjustable book cradle. [Justin] ended up using the CHDK software for the Cannon PowerShot camera to hack in a remote trigger. The scanner can manage to photograph 600 pages an hour, although that would massively increase if he ever moves up to a 2-camera setup.

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Getting More Information From Your Battery Charger

July 18, 2011 by Mike Nathan 9 Comments

echo_6_battery_charger_serial_hacking

[Dane] bought a reasonably cheap ($17) Hobbyking Echo-6 battery charger and wanted to see what sort of information he could pull from the unit. Since the charger is designed for a variety of battery chemistries and sports an LCD screen, he figured that it contained a fairly decent microcontroller which he could tap into for some useful data.

He disassembled the unit and started looking around for any useful items. He discovered that it used an ATMega32 microcontroller and had quite a few unpopulated areas on the PCB, which led [Dane] to believe that the Echo-6 shared its main board with a more robust charger. He tapped into the ATMega’s UART and began seeing data immediately. Once he figured out what was coming over the serial line, he piped the data into LogView, resulting in some nice graphs showing off the charge/discharge processes in detail.

Tapping into the Echo-6 seems easy enough for any skill level, and we assume that just about anyone would benefit from getting kind of information out of their battery charger.