Doorbell Hack Makes Coworkers Less Annoying

April 14, 2011 by Mike Nathan 6 Comments

doorbell_wav_player

Hackaday reader [Sprite_tm] works in an office building that used to house several businesses, and as a remnant of the previous configuration, a doorbell sits in the hallway just outside his office. Several of his coworkers get a kick out of ringing the doorbell each time they enter the office. While not annoyed at the practice, he was getting tired of the same old “ding-dong” and decided to shake things up a bit.

He wanted to modify the doorbell to play random sounds when triggered, but he was pressed for time as it was March 31st, and he wanted to get it installed for April Fools’ Day. Without any real plan or bill of materials in mind, he pieced things together with whatever he happened to have sitting around.

He used a design borrowed from Elm-chan in order to play wav files from an SD card with an ATTiny85, and used an L293 H-Driver as an improvised sound amplifier. After sorting out some power-related problems, and configuring the circuit to be as stingy with its battery as he could, he declared the project complete. He originally aimed to deadbug everything on the metal sleeve of the SD card socket (which is awesome), but considering the size of the speaker and the battery he selected for the project, he ended up stuffing everything into a cardboard box.

We don’t care too much about how he packaged it, we just wanted to know what his co-workers thought of his doorbell augmentation. In the end, they loved it, but we imagine this doesn’t do anything to discourage any of them from hitting the doorbell multiple times a day.

Stick around to see a quick video of his doorbell hack in action.

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K’nex Whiteboard Plotter

April 13, 2011 by Mike Nathan 8 Comments

[Jerry] has been wanting to put together a whiteboard plotter for some time and just recently got around to building one.

The plotter draws pretty much about anything he can imagine on a white board measuring just shy of 2′ x 3′. The design first started off with a Basic Stamp board at the helm, which he sourced from another project he no longer had any use for. The Stamp worked for awhile, but eventually he ran into problems due to the board’s limited 128 bytes of program space. Needing a more robust micro controller, he switched to an Arduino mid-project, which he says runs the plotter far faster than the Stamp ever did.

The plotter uses a pair of stepper motors mounted on a horizontal platform situated above the whiteboard. Much like this large-format printer we featured earlier this week, the steppers vary the length of a pair of fishing lines, moving the pen precisely across the board. As you can see in the image above, [Jerry] has been able to create some pretty intricate patterns with his plotter, and we imagine they will only get better with more refinement.

Be sure to check out his site for more details on his build process as well as several additional samples of the plotter’s capabilities.

Building An Electric Kiln

April 13, 2011 by Mike Szczys 16 Comments

[EmcySquare] is delving into some hobby-blacksmithing by making his own knives. He needs a furnace to heat the metal, and after trying out a few different forge designs he decided to attempt an electric kiln build. The final project seen above is a box within a box. The outer shell is reclaimed using old computer cases and metal shelving brackets. Inside you’ll find a box made from fire brick, with stone-wool insulation to keep the heat where it’s supposed to be.

He cut the bricks to the right size to build the inner box, then added grooves on the inside edge witch will host the heat coils. This cutting was done with an angle grinder and [EmcySquare] notes that it kicks up an extraordinary amount of brick dust to make sure you’re wearing a respirator and goggles. Once the enclosure was ready he set out to fabricate the heat coils. Twelve meters of Kanthal A1 wire was used, shortened to a neat length by shaping coils around a 1 cm diameter wooden dowel. This prototype works but future improvements plan to add automatic temperature control through a thermocouple and a relay.

Dynamic DNS Updating – No PC Required

April 12, 2011 by Mike Nathan 30 Comments

arduino_ddns

[Boris] from Open Electronics recently wrote us to share their latest creation. Like many of us, he uses DynDNS to keep his home network a FQDN’s reach away. While DynDNS is quite a convenient service, many people don’t like the idea of leaving their computer on all the time to keep the IP updated. That’s where the Arduino DDNS module comes into play.

Built using a standard ATMega328 with the Arduino bootloader installed, the module periodically checks to see if the user’s IP has changed, updating the DynDNS entry as needed. The Arduino talks to the network via a WIZnet Ethernet breakout board, contacting DynDNS’ servers to check and update the user’s IP over a series of standard HTTP requests.

We are aware that several router firmware packages such as DD-WRT have this functionality built-in, but this project makes for a nice alternative when those resources are not available.

As always, a bill of materials, PCB layouts, and Arduino Sketch code are all available for download over at the Open Electronics site.

Temperature Sensing Mug Means Never Burning Your Mouth Again

April 12, 2011 by Mike Nathan 14 Comments

temp_sensing_mug

Some people tend to get awfully attached to their favorite mug. Like an old friend, the mug holds a special place in their hearts, and there’s a weird sadness when it finally gives up the ghost. Through the winter months [Ben’s] girlfriend is never without hers, and when it broke, he decided to give her a new one with some added functionality.

He built her a temperature sensing mug that uses a rather novel way of determining how hot or cold the contents are. Instead of using a thermistor to determine the drink’s temperature, he opted to use a simple diode since it is well known that a diode’s forward voltage varies with temperature. After determining the diode’s voltage range using hot and cold beverages, he hooked it up to the ADC of a PIC12F615 micro controller. The temperature is displayed via 10 LEDs, which are driven through a pair of 8-bit shift registers and buffers since his PIC did not have enough pins to control them on its own.

He had some PCBs made, and after a handful of setbacks got everything put together. He says the mug works pretty well, though the display changes a bit more slowly than he would like. He also mentions that if he builds a second version, he will be sure to select a different PIC that has enough I/O pins to do the job, as well as use a thermistor instead of a simple diode for sensing the temperature.

Continue reading to see a brief demo video [Ben] put together.

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Giant Scale Printer

April 11, 2011 by Jason Komp 16 Comments

Giant Printer Print Head

This giant printer was originally constructed by [Komponent/LAB] in 2006 to print some large-format banners for a festival, but has recently been pulled out of storage and updated for the Venture Cup competition. The system received a few mechanical and software updates and was also mounted on tripods in order to make it fully portable.

Instead of using stepper motors and encoders to directly control the print head as in a typical printer, the entire print axis is turned vertically and the relative lengths of two belts are varied (along with the constant downward pull of gravity) to precisely control movement across the plane. The software uses HPGL plotter files and is able to scale them to fit the available printing area.

Although there are some issues with the print head wobbling due to the rapid accelerations, any printed imperfections appear to be difficult to notice from more than a few feet away. Precision could be further increased by tweaking the software to compensate for such unwanted movements.

Although we can imagine many different applications for such a printer such as architectural or street art, some fine tuning would definitely be required at very large scales and to compensate for wind, etc if done outdoors.

Here are some pictures of the build and there is a short video of it in action after the jump.

[via GeekPhysical]

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Print Your Own Header Shrouds

April 11, 2011 by Mike Szczys 10 Comments

Don’t get us wrong, printable whistles are cool and all, but these printable header shrouds make us think that filament printers like the Makerbot and RepRap might just be worth their salt. This utilitarian purpose is a departure from the souvenirs, toys, and art that we’re used to seeing from the expensive development ~~toys~~ tools.

The six and ten pin header shrouds are designed for a snug fit that makes it easy to glue them onto the plastic spacers of male pin headers. We use IDC plugs and ribbon cable all the time in our projects, but never seem to order shrouded connectors; this is perfect for us. It makes us wonder what other PCB-friendly printable designs we’ve been missing out on? Surely someone’s been printing stand-offs with threaded inserts, right? If you know of something useful that we can share with the rest of the readers, don’t hesitate to send in a tip.

[via Dangerous Prototypes]