Hackaday Links: December 25, 2011

Ah, Christmas. That wonderful time of year when you can roll out of bed to the screams and wails of children, grab a hot cocoa, and spend several hours arguing with an 8-year-old about which LEGO set to build first. Simply magical. While you’re waiting for the Doctor Who Christmas special to come on, settle down with these wonderful Christmas-themed builds that came in over the last few weeks.

One step closer to Robot Santa

Here’s an interesting way to spice up your seasonal headwear. [Mark] took a Santa hat and added a string of multicolored LEDs to the brim. The lights were picked up at a drug store for a dollar. Control is through a simple push button connected to an ATtiny13. Press the button, the lights cycle in a different pattern. Very cool, so check out the video.

A holographic holiday tree

[Auger] posted this very cool light up Christmas tree decoration on Instructables. This tree is made up of three pieces of acrylic. Different designs were laser cut into each piece of plastic – candy canes for the ‘red’ piece, stars and tinsel for the ‘yellow’ piece, and the tree for the ‘green’ piece. LEDs of the respective colors are cemented to the bottom of each bit of plastic. It’s called light piping and is used everywhere. This is the first time we’ve seen three colors, though.

This is what nerds do, and it’s awesome

[Rickard Dahlstrand] was playing around with his phone trying to take deliberately fuzzy pictures of his tree. He noticed the dashes produced from the LED Christmas lights must be produced from PCM dimming. Going through the EXIF data in the picture, he found the exposure time was 1/17th of a second. 1/17 of a second = ~ 58 ms / 5 (cycles on the picture) = ~11 ms per cycle = ~100 Hz frequency on the PCM dimming. Of course this is just about 2 times the line frequency in [Rickard]’s native Sweden, so we’ll call this confirmed. There’s no blog post for this, but we’ve never seen a clearer example of applied geekery. Simply awesome.

Yeah, we measured [Rickard] on a nerd meter

In the spirit of giving, [Johannes] decided to tell the entire world exactly how nerdy he is. He built a ‘Nerd Alert’ meter out of an old 1950s Japanese multimeter. The old guts of the meter were chucked, and a simple amp made out of a transistor amplifies the current flowing through the user’s fingers. A neat scale ([Johannes] measures somewhere between Amiga Workbench and Space invaders) replaces the old, boring, number-based one. Again, no write-up, but here’s some awesome build pictures.

Finally a use for all those old radio tubes

[AUTUIN] took apart a vacuum tube with a blow torch and a diamond cutting wheel. Surprisingly, he was able to put it back together, but not before making a wonderful Christmas ornament. There are two copper wires inside the envelope that are the leads to a single orange-red LED. The whole thing is powered by a watch battery. We’ll be sure to reference [AUTUIN] next time we have to take apart a glass bulb, because he managed not to burn, cut or blind himself.

Six things in a links post? It’s a Christmas miracle!

[Darryl] sent in a nice tool to select and display all of the hacker/maker merit badges available from Adafruit. Oh, we’re still trying to figure out who to give 10 badges to. We’re giving away skull ‘n wrench badges to the top ten hacks ever featured here. Leave a note in the comments, or tell us who should win.

Holiday wishes

Now put the computer down and go spend some time with your families, or failing that, strangers. Of course there’s an all day Doctor Who marathon, and that thing isn’t going to watch itself…

Portable bench supply carries around 10 amp-hours of juice

[Punish3r] wanted to have power for prototyping on the go. What he came up with is this little thing above. Inside you’ll find common components that let the unit provide 10 amp hours of current with a 12V 500mA output.

The storage capacity is provided by a dozen Lithium batteries. These 3.7V cheapies are wired in parallel behind a protection board. For charging and discharging, a Sparkfun LiPo charger board was used, taking care of all the work necessary to top off the batteries using a wall-wort. The final piece in the puzzle is a boost converter that provides the regulated 12v connected to the red and black banana plug receivers on the bottom of the case.

This is very much a plug-and-play design… just make sure you hook the parts up correctly and you’re up and running. We would love to see a roll-your-own boost converter circuit that include a switch or dial that lets you select common PSU voltage levels. If you’re going to the trouble to make your own board you might as well incorporate the charging circuit at the same time.

[Thanks Paul]