Gravity Pong Reaches Into the Sky

For a recent event [Norwegian Creations] decided to make something fun. They built what might just be the tallest free-standing gravity pong game out there. It’s 4.5m tall, and the LEDs in it draw over 100 amps!

What is Gravity Pong anyway? Well it’s a single person game where you get three “bounces”. A ball of light will drop from the top of the tube and the closer to the bounce-line you hit the button, the higher it will bounce. Your high score consists of how high you get the light — but if you miss the bounce line, you lose!

The structure itself is quite impressive. They’ve wrapped acrylic tubes with 1792 individually controllable RGB LEDs, in groups of four. Each section requires a power supply capable of putting out 27A @ 5V! The game is controlled by a Raspberry Pi 2 which controls a Pixelpusher to manipulate the LEDs. It’s connected to the Internet, so high scores can be automatically uploaded!

When it comes to pong though, we quite enjoy playing it with $5,000 construction crane controllers — because why not?

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RPiTX Turns Rasberry Pi into Versatile Radio Transmitter

Since the discovery that some USB TV tuner dongles could be used to monitor radio waves across a huge amount of spectrum, the software-defined radio world has exploded with interest. The one limiting factor, though, has been that the dongles can only receive signals; they can’t transmit them. [Evariste Okcestbon, F5OEO] (if that is his real name! Ok c’est bon = Ok this is good) has written some software that will get you transmitting using SDR with only a Raspberry Pi and a wire.

There have been projects in the past that use a Pi to broadcast radio (PiFM), but this new software (RPiTX) takes it a couple steps further. Using just an appropriately-sized wire connected to one of the GPIO pins, the Raspberry Pi is capable of broadcasting using FM, AM, SSB, SSTV, or FSQ signals. This greatly increases the potential of this simple computer-turned-transmitter and anyone should be able to get a lot of use out of it. In the video demo below the break, [Evariste] records a wireless doorbell signal and then re-transmits it using just the Rasbperry Pi.

The RPiTX code is available on GitHub if you want to try it out. And it should go without saying that you will most likely need an amateur radio license of some sort to use most of these features, depending on your locale. If you don’t have a ham radio license yet, you don’t need one to listen if you want to get started in the world of SDR. But a ham license isn’t hard to get and at this point it shouldn’t take much convincing for you to get transmitting.

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Dalek-Berry-Pi Mower

There’s something about lawn mowers and hackers. A desire to make them into smart, independent robots. Probably in preparation for the day when Skynet becomes self-aware or the Borg collective comes along to assimilate them into the hive. [Ostafichuk] wanted his to be ready when that happens, so he’s building a Raspberry-Pi powered, Dalek costumed Lawn Mower that is still a work in progress since starting on it in 2014. According to him,  “commercial robot lawn mowers are too expensive and not nearly terrifying enough to be any fun, so I guess I will just have to build something myself…”

His first report describes the basic skeletal structure he built using scrap pieces of wood. Two large lawn tractor wheels and a third pivot wheel help with locomotion. The two large wheels are driven by geared motors originally meant for car seat height adjustments. A deep cycle 12V battery, and solar panels for charging would take care of power. A raspberry-pi provides the brain power for the Dalek-Mower and L298N based drivers help drive the motors. The body was built from some more planks of scrap wood that he had lying around. While waiting around for several parts to arrive – ultrasonic sensors, accelerometer, 5V power supply modules – he started to paint and decorate the wood work. Generous amounts of water repellent paint and duct tape were used to make it weather proof. His initial plan was to use python for the code, but he later switched to programming in c along with wiringPi library. Code for the project is available from his bitbucket git repository. Load testing revealed that the L298N drivers were not suitable for the high current drawn by the motors, so he changed over to relays to drive them.

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Tracking the Hamster Marathon

[Michelle Leonhart] has two Roborovski hamsters (which, despite the name, are organic animals and not mechanical). She discovered that they seem to run on the hamster wheel all the time. A little Wikipedia research turned up an interesting factoid: This particular breed of hamster is among the most active and runs the equivalent of four human marathons a night. Of course, we always believe everything we read on Wikipedia, but not [Michelle]. She set out to determine if this was an accurate statement.

She had already added a ball bearing to the critters’ wheel to silence it by cannibalizing an old VCR. What she needed was the equivalent of a hamster pedometer. A Raspberry Pi and a Hall effect sensor did the trick. At least for the raw measurement. But it still left the question: how much distance is a hamster marathon?

01_hamster_stride_measurement[Michelle] went all scientific method on the question. She determined that an average human female’s stride is 2.2 feet which works out to 2400 strides per mile. A marathon is 26.2 miles (based on the distance Pheidippides supposedly ran to inform Athens of victory after the battle of Marathon). This still left the question of the length of a hamster’s stride. Surprisingly, there was no definitive answer, and [Michelle] proposed letting them run through ink and then tracking their footsteps. Luckily, [Zed Shaw] heard about her plan on Twitter and suggested pointing a webcam up through the plastic bottom of the cage along with a scale. That did the trick and [Michelle] measured her hamster’s stride at about 0.166 feet (see right).

Now it was a simple matter of math to determine that a hamster marathon is just under 10,500 steps. Logging the data to SQLite via ThingSpeak for a month led [Michelle] to the conclusion: her hamsters didn’t run 4 marathon’s worth of steps in a night. In fact, they never really got much over 2 marathons.

Does [Michelle] have lazy hamsters, or did she just add to our body of scientific knowledge about rodents? We don’t know. But we couldn’t help but admire her methods and her open source data logging code would probably be useful for some non-hamster activities.

If you are super competitive, you could use [Michelle’s] data to handicap yourself and challenge your pets to a race. But it would probably be cooler to build them their own Starship Trooper-style walkers. Either way, you can check out [Michelle’s] little marathon runners in the video below.

Raspberry Pi Halloween Voice Changer

[Dave Shevett] has spent a lot of time (more than a year) expanding his Technomancer costume along with the companion (Arduino-driven) magic staff. He found, however, he needed a way to get his voice out from behind the mask. If you are going to go through that much trouble, you might as well augment your voice at the same time, right?

[Dave’s] voice changer uses a Raspberry Pi which isn’t all that complicated. The Pi uses Linux, and Unix–the predecessor to Linux–has a long history of having little tools you can string together to do big jobs. So once you have a Pi and a sound card, the rest is just some Linux command line wizardry.

There’s a battery and a small portable amplifier to get that booming voice. Since you don’t want to lug a keyboard and monitor around to handle every reboot, [Dave] set the Pi up to run his voice-changing scripts on each reboot.

This is a great example of why old Unix programmers make small tools and use the shell to join them together. [Dave’s] voice changer is pretty much just some off the shelf parts and a  script so simple it hardly qualifies as programming in any real sense. In fact, it is essentially one line of “code”:

play "|rec --buffer 2048 -d pitch -300 echos 0.8 0.88 100 0.6 150 .5 band 1.2k 1.5k"

Sure, there is some street cred in embedded development to doing everything the hard way, but with the advent of cheap embedded Linux systems, why not take advantage of the tools where you can?

If you want a more roll-your-own approach, you can pick up your Arduino or break out an audio mixer (but good luck getting it in your costume).

Listen to the Rain, Raspberry Pi Style

There’s an old proverb algebra teachers often recite: You have to use what you know to find out what you don’t know. The same could be said about sensors. For example, analog to digital converters use something computers are good at finding (like time) and use it to determine something they aren’t good at finding (like voltage). So how do you detect rainfall? If you are [lowflyerUK], you use the microphone in your web camera and a Raspberry Pi.

The idea was to reduce irrigation usage based on rainfall, so an exact measurement isn’t necessary. The Python code that analyzes the audio input is calibrated with three configuration parameters and attempts to remove wind noise. Even so, it needs to be in a room that gets a lot of noise from rainfall and ambient noise can throw the reading off.

The weather service is never going to adopt this system. Still, it is a great example of taking something you know and using it to get something you don’t know. If you want a more complete weather station, we have a few options for you.

Raspberry Pi Sense HAT Super Weather Dashboard

[InitialState] posted a great multipart tutorial about building what he calls a “Hyper-local Weather Dashboard.” In plain language, he created a Raspberry Pi-based web page that fuses weather data from Wunderground along with locally sensed weather data.

The tutorial has thee parts. The first part covers reading data from Wunderground using their developer’s API (you’ll need an API key; a free one is good for 500 queries a day). The second part covers using the Pi Sense HAT to measure local temperature, humidity, and pressure. The final part ties it all together using producing the hyper-local weather dashboard (whatever that really means).

We talked about the Sensor HAT earlier (and there’s more info in the video, below). Seems like those lights could do something, although that wouldn’t do you any good over a web interface. This is a good-looking project (and tutorial) and easy enough that it would be a good place to start
experimenting with the Raspberry Pi.

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