[Brad Graham] wrote in to let us know about his electric bike data dump over at atomiczombie.com, written just for us! Last we heard from [Brad] he was building some serious robots and freakishly tall tallbikes but since the weather has turned for the chilly its time to focus on indoor projects. Using a combination of robot parts, electrical conduit, and OEM bikes for the frames [Brad] takes us through several of his builds and all the various complications trying to drive the (often very powerful) electric motors. The builds range from scrapping motors and controllers to full blown drop in hub motor systems that can combine human and electric power. There is even an electric pusher cargo cart designed for a cooler, because beers are not going to haul themselves around.

Don’t forget to check out the AtomicZombie website for a ton of useful tips to chopping up bikes for your own mutant transpiration projects, we know we will. Thanks [Brad]!

Buildlounge and Full Spectrum Laser have decided to give away a laser cutter to whoever comes up with the best project involving light.

The contest is in part sponsored by  adafruit industries. The focus of the contest is light – just design something around light, submit it, and you’re in the drawing for your own laser cutter. A solar oven, photophone, solar fiber-optic lighting and hacking apart an old overhead projector are suggested on the contest page, but the winning project will probably be much cooler.

Entries are due by January 1st. First prize is Full Spectrum Laser’s 40 Watt laser cutter, second is an awesome green laser pointer from Wicked Lasers, and third prize is an EL wire starter kit from Adafruit. Entries are due by January 1st, so we expect to see a lot of awesome submissions on the Hack A Day tip line between now and New Years.

[Paul] wrote in to tell us about his brand new hack hosting service, HackHut. Based on WordPress with some modifications, it is definitely worth keeping an eye on as new features emerge.

Instructabliss

Speaking of project hosting, Instructables are a common source of projects as well as complaints. Instructabliss by [Daid] is an often mentioned solution in our comments, and we thought we would bring it up so commenters don’t have to. We understand why it was made and think it was a clever hack, but we don’t officially endorse it. We survive on Ad revenue, if someone were doing this to us, it would hurt. We’re also not sure about the legalities of such a service, so keep us updated.

Grass Burning Robot

[Sebastian] brings us his grass burning, flame throwing robot. This robot takes in SVG files to create its burn path, and burns away. Not too many details, but be sure to check out the photos on his site.

[via Make]

[Stephen Eaton] created an enclosure and shared his process in a pair of blog post. We thought is was amusing that he remarks on how rarely his projects get the to point that you’d want to make an enclosure for them. We’ve certainly got a lot of bare-PCB creations lying around. But when it does come time, we think his fabrication method is a good way to go.

First of all, he didn’t start from scratch. He already had a SparkFun project case sitting around. The problem is figuring how to make it work for your situation. We’ve used a drill, a Dremel, and a file in the past and that yields passable results but nothing that would be mistaken for anything other than a carefully mangled project box. [Stephen] decided to mill the openings he needed from the box, which yielded professional looking results. He started by emailing SparkFun and asking if they could give him a 3D model of the project box and the obliged. He then modeled the LCD screen, LED light pipes, button, USB port, and SD socket. From there it was off to the mill with a custom jig and a few tricks we think you’ll appreciate. The end result is just another reason to build the CNC mill you’ve had on your mind for so long.

As far as pranks go, [Austin Shaf's] wireless hidden water gun is a real treat. The video above goes over a brief explanation and shows the setup in action. The prankster holds onto a wireless AVR remote, and when the unsuspecting victim walks by, he activates a second AVR controlling a pump; spraying water everywhere.

While most of us are out of school by now, the project would still be a fun office or perhaps street prank. If you’re one for registering, schematics and source code can be found at AVRFreaks. Alternatively, check after the jump for a copy of both.

Related: Office Pranks, and Water Guns.

(Click for big, or right click save as.)

Here for TX.zip

Here for RX.zip

Looking for an interesting project to do using an Atmel Mega644? Students at Cornell University have got you covered. They were required to choose, design, and build a project using the microcontroller; and this year is quite promising with video object tracking, the always popular theremins, helicopters, Potentiostats, even Pavlovian conditioned mosquitoes, and more.

Of course all the previous years are included as well, making over 350 projects total.

[Thanks Bruce Land]

We’d like to spend some time talking about documenting your project and sharing it with the world. For many, the goal is to become an Internet sensation, hopefully for the right reasons. Taking a bit more time to make certain you do a great job of sharing your information will pay off. Here at hackaday.comwe focus on technological wonders but these guidelines should work well at improving the desirability of anything you might want to share on the interweb.

1. Pictures

Yes, you need to have a picture to go with your project. Even if you did something that can’t be captured on camera you must have a photo. An example of this is the main photo for our recent udev rules post. It’s just a udev logo with some words but it immediately shows what the article is about.

This is doubly important for concept illustrations, flow control charts, schematics, assembly diagrams, etc. Visual materials complement your writeup. They also encourage readers to spend more time looking at your project, once again increasing the chance that they’ll share this with others.

Multiple pictures are a huge plus, even if some of them are just links to photo sharing sites. There are many examples of posts that show a few pictures and then have a linkpointing to more. Having several eye-catching shot options to choose from increases the chance that someone will blog about your project. Think of the extra photos as your press kit.

2. Descriptions for all levels of readers

Have you just completed something that is cool for everyone to look at but the gory details require specialized background knowledge? Make sure you include a layman’s description of what you set out to do and what was accomplished. But don’t make the mistake of dumbing everything down, many readers are looking for things they can learn from and adapt into their own projects. Strike a nice balance that includes a general overview at the beginning, details in the middle, and a conclusion that gives a broad overview of your accomplishments.

3. Submit it yourself

Hoping that everyone you know will head to your site and then tell your friends about it? Why not be more active? You can submit your project directly to Hack a Day; most popular sites have some way of doing this. If you’ve asked questions on your favorite forum throughout the project, make sure you post an update to all of those threads with a link to the finished project page. We always want to see the fruits of one’s labor so we subscribe to threads that look interesting. This added step will bring the kind of traffic you want: the admirers who wish theyhad pulled off the feat that you completed.

4. Site stability

Often called the Digg effect or the Slashdot effect, having your site go down because of traffic is a bad thing. If you want everyone in the world to take a look at your project, make sure you have chosen a host that can handle the traffic. Clicking through to a dead link will turn readers away (obviously). If you’re hosting on your home server, keep the link to yourself and your closest friends.

5. Post follow-ups

Did you find a way to make your project better? Make sure to post a follow-up, then link it at the bottom of the original post and vice-versa. A great example of this is the twatch, which had a twatch-in-a-picture-frame follow-up. The original project was an interesting one, the follow-up is eye-catching and fun; each builds on the popularity of the other. Once you’ve posted a useful followup, go back to step 3 and promote it!

6. No Spamming, no cheating

Flooding forums or emails that are unrelated to your project is Spam. The same goes for leaving links in comments that don’t have any relation to what you accomplished. If you are trying to syphon hits by tricking people into clicking a link then you are cheating. Become a sensation for the right reason: because people love your project.

Conclusion: it didn’t work

Well, there’s only room for so many sensations. But, if you followed our advice you have a quality writeup of your post and we’re certain many people took a look at it. This builds your reputation and increases the chances that your next project could go viral.

We received quite a bit of tips, after posting about the 150$ high altitude balloon project, from communities and teams who had done similar tasks. There is more to these projects than simply filling a balloon and attaching a camera, so in order to allow everyone their 7 seconds of well deserved fame, we’ve compiled a quick list of similar high altitude balloons. Catch it after the break.

Do note, these are in no order or rank.

RPI Electronics club, sent in their Imaging Balloon of Science. Supposedly built in under 30 hours and runs Linux.

Bang Goes the Theory had their own Space By Balloon program after being inspired by Joe Kittinger.

Brushing up on my Spanish, Meteotek08 is a dual high altitude balloon that reached a height of 30,000 meters.

Ensure II is a very impressive setup that actually recorded its flight with video cameras (video above).

NSTAR, or Nebraska Stratospheric Amateur Radio, have sent up several high altitude balloons within the past couple of months.

Last, but certainly not least is the Amateur Radio High Altitude Ballooning group who have been sending up balloons since 2001!

Thanks to everyone who commented and sent in a tip!

The basic design for the RGB keypad came from [JMG]‘s Arduino based Monome clone. He used an Arduino, and multiplexed RGB LEDs with some digital potentiometers to create a color mixing keypad. Since we couldn’t fit the complete 4×4 keypad into a standard 2 gang wall box, we chopped the design down to a 2×4 matrix. This cuts down significantly on the cost to build the keypad and makes the code that much easier to digest.

To build your own RGB keypad, you’ll need the following:

• An electric door strike (Smarthome.com)
• A locking door handle (Any hardware store)
• An Arduino or compatible clone (Sparkfun, adafruit and others)
• 1 TIP120 transistor
• 1 1N4001 diode
• 10 1N4148 diodes
• 4 2n2222 transistors
• 1 Monome style keypad (Sparkfun Electronics)
• 1 Keypad PC board (Sparkfun Electronics)
• 8 RGB LEDs (Sparkfun Electronics)
• 1 7805 voltage regulator
• 4 100 ohm resistors
• 2 150 ohm resistors
• 8 1 kohm resistors

To reliably lock and unlock the door, we ordered an electric door strike. We scored this one as an open box item from Smarthome.com. It’s a 12 Volt DC unit designed just for Schlage commercial door locks. The edge of the strike is slightly recessed from the mounting plate, so it might not work with certain locks. It features a thinner body than the non-recessed version, which will allow us to cut a smaller but deeper hole in the door frame. Without power, the strike stays locked, keeping the locking door shut. When 12 volts is applied to the coil, the strike releases, allowing the door to be pulled open. For the prototype build, you don’t have to purchase a strike just yet; you can use a LED and a resistor to indicate the door lock state for testing your code.

The keypad is actually built from two separate circuits that physically overlap. The input circuit is a simple keypad matrix. To read each button push, the Arduino brings one keypad input line high and checks the voltage of the four output lines in order. The diodes on the PC board prevent feedback across the rows and columns.

The RGB LEDs are lit via a completely separate set of circuits. Each row of like colored LEDs is brightness controlled by a digital potentiometer. The digital pot works just like a normal pot, but it’s digitally controlled by the Arduino. Meanwhile, each column of LEDs is activated by a separate transistor. By quickly changing the resistance and stepping through the columns, each LED will appear to be individually controlled.

The door strike circuit is pretty simple. Since it contains a coil, we’ll treat it like the coil of a stepper motor and use a TIP120 transistor to supply the power. When power is removed from a coil, the collapsing magnetic field creates a current within the coil. To keep the TIP120 from burning out, we’ll add a diode to handle the surge created by the field breakdown.

update: [Triffid] pointed out that the diode is better placed in parallel with the coil to handle the transient surge. He’s correct, but the circuit here has operated perfectly for several months, so you’ll be fine either way.

The traces for the buttons looked a bit challenging to etch at home, so we ordered this PC board that Sparkfun produces for their keypads. Sparkfun helpfully provides the layout for these keys in their eagle library, so you can make your own PCB if you prefer. For reliability, you’ll probably want to have it commercially produced. The board wasn’t really designed to break apart, but after a review of the traces and vias we decided that we could get away with trimming a couple of rows from the board.

We carefully split the board down the middle with a band saw. If you look closely, you can see where some of the vias were actually cut in half. (A paper cutter might work in a pinch) Don’t forget to put on a mask to keep the dust out of your lungs.

Cutting the button pad is much easier. The pads have pre-scored lines that just need a quick swipe of a sharp knife or scissors to separate them.

The new shorter PCB only needs a few parts: some 1N4148 diodes and the RGB LEDs. The silkscreen on the board indicates the direction and position of diodes and LEDs.

Once you solder on the 1n4148 diodes, cut them as close to the PC board as you can. Flat head cutters like these work extremely well. The keypad will sit on this side of the board and we want to make sure that it can sit as flat as possible.

Install the LEDs in the orientation indicated by the silk screen. Carefully push them down into the board until they’re inserted just like this. If you let them stick up too high, they’ll interfere with the keypad buttons being pushed.

Once you’ve soldered all the LEDs in place, clip them flush as well. Then you’ll need to add some cable to jumper from the keypad to the interface board we’ll build. We used some old CAT-5 wiring. Since each axis of the board has eight pins, it’s perfect for the application.

Each RGB LED has three LEDs inside the package. They share a common terminal and have a single separate lead coming out. Because they have different characteristics – that is brightness, current and voltage requirements, we spent some time testing out various combinations. We even murdered a couple of innocent $2 LEDs just for you. Hey, the other two colors are still usable…

After some experimentation, we managed to find the right combination to create some fairly white light. The requirements will vary between manufacturers, but for the Sparkfun LEDs we found that a pair of 100 ohm resistors and a single 150 ohm resistor blended the red, green and blue fairly well.

The color combination was hard on the eyes until we put the keypad over the LED to double check our findings. In real life, you can see some blending lines from the offset of each LED, but it still looks great.

The circuit has plenty of components, but it’s pretty easy to build. We’ll break everything up by section to keep things easy. You can download the all of the schematics, Eagle project files, and code for the Arduino here.

The digital pot has six outputs. Each of these will power a row of red, green or blue LEDs, via a color matching resistor. The digital potentiometer wiring comes directly from this how-to. You can read it if you need more information, or use our quick version:

• Connect AD5206 pins 3, 6, 10, 13, 16, 21 and 24 to 5v.
• Connect pins 1, 4, 9, 12, 15, 18, 19, and 22 to ground.
• Connect pot pin 5 to Arduino pin 10
• Connect pot pin 7 to Arduino pin 11
• Connect pot pin 8 to Arduino pin 13

Grab four 100 ohm resistors and two 150 ohm resistors. Place them in the breadboard in a row with each end in a separate bus. (Across the center of the board is easiest) Connect the six LED leads from the keypad to one end of each resistor – reds get the 150′s and blue and green into the 100′s. Here’s the connection order we used.

• RED3 to a 150 ohm resistor to pot pin 14
• GREEN3 to a 100 ohm resistor to pot pin 11
• BLUE3 to a 100 ohm resistor to pot pin 2
• RED4 to a 150 ohm resistor to pot pin 23
• GREEN4 to a 100 ohm resistor to pot pin 20
• BLUE4 to a 100 ohm resistor to pot pin 17

To ground the LED busses, we’ll be using four 2N2222 transistors. The Arduino will trigger each transistor individually through a 1Kohm resistor. The collector of each transistor connects to a ground line from the keypad. The emitter of each transistor is connected to the ground. The four transistor select lines connect to Arduino pins 0, 1, 2, and 3. Yes, they’re marked Analog in, but it doesn’t matter.

The keypad switch matrix is connected in four columns and two rows. Each of the four columns gets a pull-down resistor. We used 1Kohm resistors for R11, R12, R13, and R14; one lead connects to the columns and the other is grounded.

Arduino pins 2 and 3 should connect to the two ungrounded lines, which are marked SWITCH3 and SWITCH4 on the PC board (5 and 6 on the schematic).

Arduino pins 6, 7, 8, and 9 should connect to the four output lines marked SWT-GND1, SWT-GND2, SWT-GND3, and SWT-GND4 (1-4 on the schematic).

The final version of the board takes a 12VDC input to drive the door lock. We added a 7805 to drop the 12V down to 5V for the Arduino. You don’t need it for the prototype version unless you want to test the striker. The Arduino has an on-board regulator, but 7805′s are cheap and it helps reduce the load on the Arduino’s built in regulator. For code development, we just connected an LED with a resistor to the output line that will control the door lock.

With everything wired in the prototyping board, it’s time to test things out. With any luck, you’ll soon be rewarded by the pulsing, glowing sight of several RGB LEDs under your tender digits.

Programming the Arduino is a snap. Just download the software for your OS here. Now follow the Getting Started guide to get the Arduino software talking to the Arduino board. Once you’ve enjoyed the blinking LED demo, come back here and get your keypad rolling.

Once you’ve set up and tested your Arduino, it’s time to test out your prototype. Download the button_test code from here. Paste it into a new sketch and upload it to the Arduino. Click the serial console button and you should start seeing dots accumulating in the window. If you press a button on the pad, the Arduino should print a message to the console and toggle the lock output state.

Once your buttons are tested, you’ll probably want to try out your LEDs. Grab the RGB_light_fade routine from the same page and upload it to your Arduino. You should get treated to a nice little light show. This is our favorite demo because it really shows off the color mixing capabilities of the digital potentiometer.

With your LEDs and buttons working, you can grab the row_entry_pad_meffect lock code from the same place and upload it. Now the keypad should start flashing blue buttons while it’s idle. On key presses, the keys will change colors. By entering the correct color code, the pad will flash green and unlock the door for 10 seconds. If you go over the limit counter, it will flash red for 30 seconds.

Next time we’ll show you how to make the permanent version of the keypad, walk through the code for the Arduino, make the PC board, cut a custom wall plate, and install the lock strike.

The video being played is the impressive Python SVG demo Die Ewigkeit schmertz.

[via laughing squid]