Rocketry is very exciting hobby. But building and letting plain rockets wouldn’t be so fun without countdown. For this you don’t need much – An Arduino, ULN2003 chip to actuate relay and dot matrix LED display – the bigger the better.

You can guess what it does actually. So code is pretty simple. When button is pressed countdown starts. When it reaches zero, Arduino triggers the relay where the ignition is connected. That’s it – enjoy the show.

This one was designed to control air conditioner which seems lacks some automation. Anyway this project suits for many purposes and seems to be very simple: Arduino, thermal resistor and servo motor that turns conditioner knob.

The project has some shortcomings like draining 9V battery with 5V voltage regulator. And probably code needs to be tweaked for more efficiency. Anyway this a good start and great example of simple solutions that may help to lower electrical bills.

The number of Arduino shields is growing every day. So why not to build own by yourself too. Starting new things may seem a little bit tricky. Well not any more. Check out this tutorial on how to make Arduino shield PCBs. It takes through all steps needed to complete fully functional Arduino shield with no errors.

Tutorial is written by using CadSoft’s EAGLE package. And uses a SparkFun EAGLE library to place necessary components where the most important in this case is pre-built Arduino Shield footprint. So build an Arduino shield and don’t mess with wiring any more.

When building a car model like this Derby consider adding some electronics that makes it more unique and luxurious. MYX have made excellent combination of pinewood Derby model and Arduino (actually Funnle IO) controlled front with bunch of SMD LEDs that makes various effects like strobing, pulsing, fading and blinking.

Joule Thief PWD from MYX on Vimeo.

Everything looks really neat – even PCB is specially traced to look great with specially shaped ornaments. So sit back and enjoy the ride.

We’ve seen a reverse geocathing box earlier. So this one is even more fun as it has more great features. Deluxe reverse Geocache box is built around Arduino Pro 3.3V board which is interfaced with 20 channel Helical GPS receiver and a big LCD.

When puzzle is solved a box dispenses a key which allows unlocking it. And the last thing which is really great – camera. It takes random shots of the current user trying to solve puzzle. Seems that reverse geocaching turns activity upside down – probably next box will be with map on LCD so you won’t need additional GPS locator.