CO2 Powered Pinewood Derby Car Is Definitely Cheating

The Pinewood Derby is a classic Cub Scout competition where dads and sons come together to build a small-scale race car. You start with a kit that includes a block of wood for the body, as well as four plastic wheels and four nails to act as axles. Most innovations in the ‘sport’ center around reducing friction between the wheels and the axles, and making the body as aerodynamic as possible.

This year [Sliptronic] grabbed an extra kit and threw the rules out the window by powering the car with compressed carbon dioxide. He used a 3D printer to make a housing for two CO2 cartridges that mounts on the center of the chassis. An official Pinewood Derby race track is on an incline and has a wooden gate that keeps each car in place until it is dropped to start the race. [Sliptronic] is using this gate as the triggering mechanism. Springs on either side of the car pull against an arm at the back of the vehicle. This arm is held in place by a rod protruding out the front of the vehicle. When the start gate is dropped that rod releases the trigger, which is pulled up by the springs to pierce the CO2 cartridges. You can see an overview of how that mechanism works in the video after the break.

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Animated Paper

What if you could make paper react on physical input. Maybe you want it to shy away and close up if someone reaches for it too fast, or maybe you want some realistic paper flowers? Moving on to that great first step is Animated Paper, which is simply nitinol memory wire bonded to paper via our favorite tool, duct tape.

Memory wire is first bent to its desired shape, and in order for it to hold that shape it needs to be heated to about 540 degrees Celsius, which is a easy task for a propane torch. Once it has its memory shape the wire can be bent into any shape desired, and when heated to about 70 degrees Celsius will return to its original set shape.

Taped down to a sheet of paper and letting some current from a battery run though it the wire quickly warms up and animates the paper, which could be exactly what one needs in a more artsy robot or electronic display. Join us after the break for a short video.

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No PCIE Slot? Just Add One

[Leslie] likes his little Samsung N150 Plus netbook. While it packs enough punch for almost everything, it lacks in High Definition video power. That is where a Broadcom Crystal HD mini PCI express card comes in, as these little video decoders are made just for netbooks needing some HD love, but the problem is, his netbook only has one PCI express slot in it, and its occupied by the 802.11N card.

Not being bummed out by this, and not wanting to use a USB dongle device he just ripped open his netbook and added a second pci express connector to the pads on the motherboard. Sourcing the header from mouser, the install seems quick n easy, especially since Samsung was nice enough to have the pad’s tinned already, so just a little flux and a steady hand you’re good to go.

Unfortunately, there are some hidden gotcha’s as the newly installed slot is not “full featured” that both the Broadcom card and the stock wireless N card require, but he had a wireless G card that ran just fine in the newly added slot, so now its time to rock some full screen HD Hulu.

Weather Station Turned Data Logger

Home brewing the perfect beer (or root beer in this case) requires a watchful eye and stable temperature, but [Gregory] has a house that is 120 years old. While we are sure it is a beautiful home, it does have its usual historical issues including temperature fluctuations.

[Gregory] suspects this to be the reason why his root beer is not carbonating, but to be 100% sure he grabbed a weather station (and atomic clock) with a wireless remote thermometer and got hacking. After popping the station apart he was able to quickly isolate the radio receiver and figure out the signaling, a few connections to an arduino, and now he can keep track of the temperature as its logged on to his PC.

Hopefully he can find out if this is his issue or not. Join us after the break for a quick video.

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Automatic Ball Launcher Is For The Dogs


A while back, [Dino] built an automatic ball launcher for his dogs, but he wanted to revise it to make it smaller and a bit more user-friendly. While watching an episode of “Prototype This”, he came across a great idea to improve his launcher, so off to the workshop he went.

He repurposed a power window motor from a car, and mounted it to some wood-reinforced aluminum sheeting in his garage. He added a piece of aluminum tubing to serve as a spring-loaded launch arm, which is drawn back by a small lever attached to the window motor.

When a ball is dropped onto a switch at the bottom of the launcher, the window motor starts turning, which pulls the launch arm back into place. Once the arm reaches the tipping point, the spring snaps it forward, launching the ball across the yard. The lever attached to the window motor eventually makes its way back under the launch arm, and is stopped by a switch that is also attached to the motor.

After the prototype was finished, he added some more wood to protect the mechanism from his dogs and vice versa. A hopper was added to the top of the structure to allow the dogs to load the launcher themselves, after a bit of training.

Now, some of you might wonder what is wrong with [Dino’s] arm. Truth be told, it works just fine. If you are a frequent Hack-a-Day visitor, you know that he spends plenty of time in the workshop, so this is an easy way to let the dogs entertain themselves until their owner is ready to play.

Check out the video embedded below for a demonstration of the launcher, as well as a detailed walkthrough of how the mechanism works.

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Wireless Weather Station Obsessively Reports The Temperature


[nuumio] has been hard at work building a Tweeting weather station, which he recently got up and running. The weather station is built from three major components, a Linux PC for data storage and Tweeting, a main weather sensor unit, and a remote unit.

The remote unit sits outside and includes includes both a pressure and humidity/temperature sensor. The sensors are polled every 20 seconds, reporting the data back to the main unit via a 434 MHz RF transceiver. The remote sensor also records the ambient light level and the remaining battery voltage, sending that data to the main unit for good measure.

The main unit sits inside his house and records the same temperature and humidity data as the external unit. The main unit adds its data to the packets sent by the remote unit and transmits them to the PC via USB. The PC calculates the minimum and maximum temperatures for the last 12-hour and 24 -hour periods before sending that data back to the main unit to be displayed on its LCD panel. Every 10 minutes, the computer also posts the weather data on Twitter.

If you are looking to build your own weather station, [nuumio] has provided all of the source code for his project on his web page. However, he does admit that he was too lazy to draw up a schematic, so you are on your own in that department.