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

automatic_ball_launcher

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

obsessive_weather_station

[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.

Pi Phone Lulls You To Sleep With The Digits Of Pi

As you well know, today is March 14th – aka “Pi Day”.

Celebrated in math classrooms around the country, this truly is a celebration that belongs to the geeks. Here at Hack-a-Day, we too love Pi day, though we might not outwardly celebrate it with as much gusto as expressed by some of our readers.

[Chris Poole] is one Hack-a-Day fan who knows how to make the most of this mathematical holiday. He has put together a neat SIP-based phone service that reads Pi aloud to anyone who calls. He is running Asterisk in combination with Perl to read off the numbers, and is using a free SIP DID number to accept the calls. We gave it a shot earlier today, and were greeted by a gentle synthesized voice reading off the numbers of Pi. We’re not sure how many digits it is programmed to handle, as we stopped after about 20, so give him a call and let us know how many digits you make it through.

As a parting note, no Pi Day would be complete without a few obligatory Pi-related (albeit old) web comics and pastry concoctions, so here you go!

XKCD – Pi Equals…

XKCD – e to the Pi Times i

XKCD – E to the Pi Minus Pi

Spherical Pi Pie

Battery Capacity Tester Lifts The Veil On Manufacturer Capacity Claims

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[Nick] was tasked with building a battery capacity tester by one of his teachers in order to test some aftermarket batteries that were purchased for their Vex robotics lab. The batteries were cheaper than the official version, but boasted more than twice the capacity. Fairly skeptical of the rating, he got to work designing his circuit.

He originally planned on discharging the battery through a resistor and measuring the voltage with a PIC microcontroller. After prototyping the circuit, he found that the PIC did not have enough storage space for the data he was collecting, and that there were issues with fluctuating current as the voltage decreased.

Undeterred, he built a new tester using a Teensy microcontroller and a different discharging circuit using a LM317T. This second version not only included an LCD screen to track the discharging process in real-time, but it also dumps all of the data and calculations to a spreadsheet on the computer connected to the Teensy.

The capacity tester works pretty well, according to [Nick]. He says that most batteries overestimate their capacity, and that his meter is getting readings within an acceptable variance when testing known good batteries. What about those knock-off batteries from China?  He discovered that they can hold about half the charge that they claim – it’s a good thing he decided to test them out!

While he provides the software he used for the tester, there are no schematics to be found. Check out some of the other battery capacity testers we have featured in the past for tips on building one yourself.

Guide For Working With AVR Microcontrollers

[Q] wrote in to let us know about the AVR-Guide he’s been working on. It looks like he’s finished posting about 80% of the content he planned for in his initial draft outline. We read through several of the sections and found them to be concise, yet able to present information in a way that’s easy to grasp. The screenshot above shows the most basic block of information to get started with AVR microcontrollers. We’ve covered the same information in our AVR tutorial series and think that reading through both will give you a strong understanding of the knowledge needed to work with 8-bit microcontrollers with confidence. But this resource doesn’t stop after the basics. If you’re looking to bolster your knowledge of all the features the AVR line has to offer there’s also sections explaining Digital I/O, Interrupts, Timers, Analog I/O, Communications, and Miscellaneous topics.

The site is called QEEWiki. We logged in using a Google account (this is hosted as a Google site) but didn’t see a way to edit the information. If this truly is a Wiki and you know how to edit pages please leave a comment about it after the break.

DIY Digital Pinball Console Plays Hundreds Of Games

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Pinball machines, while likely considered pretty retro technology by most, are still a fun and engaging way to waste a little time. The problem with pinball machines is that they take up a lot of space, making the hobby of collecting them pretty prohibitive unless you have tons of spare room in your house.

[tbarklay] loves pinball machines but doesn’t have to room for an elaborate collection. Rather than purchase one machine, he opted to build his own pinball table that can be used to play any number of games. He repurposed an old PC to power his table, connecting it to a 24″ LCD panel for the main display board. A custom cabinet was built to contain the large LCD panel as well as the computer. A 19″ LCD screen was mounted on top of the cabinet to serve as the backglass display. A set of arcade buttons were also added to the console to provide realistic paddle control.

While we don’t have a video of his particular table in action, check out this video we found of  a pinball machine that uses the same setup.

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