The Butt Lamp: Light From Where The Sun Don’t Shine

January 23, 2014 by 28 Comments

[Trent] is one of those guys who can make things happen. A friend of his gifted him a  mannequin derriere simply because he knew [Trent] would do something fun with it. “Something fun” turned out to be sound reactive LED butt. At first blush, this sounds like just another light organ. This butt has a few tricks up its …. sleeve which warrant a closer look. The light comes from some off the shelf 5050 style RGB LED strip. The controller is [Trent’s] own design. He started with the ever popular MSGEQ7 7 Band Graphic Equalizer Display Filter, a chip we’ve seen before. The MSGEQ7 performs all the band filtering and outputs 7 analog levels corresponding to the amplitude of the input signal in that band. The outputs are fed into an ATTiny84, which drives the RGB strip through transistors.

The ATTiny84 isn’t just running a PWM loop. At startup, it takes 10 samples from each frequency band. The 10 samples are then averaged, and used to create a noise filter. The noise filter helps to remove any ambient sound or distortions created by the microphone. Each band is then averaged and peak detected. The difference between the peak and the noise is the dynamic range for that band. The ATTiny84 remaps each analog sample to be an 8 bit value fitting within that dynamic range. The last step is to translate  the remapped signal values through a gamma lookup table. The gamma table was created to make the bright and dark colors stand out even more. [Trent] says the net result is that snare and kick drum sounds really pop compared to the rest of the music.

Without making this lamp the butt of too many jokes, we’d like to say we love what [Trent] has done. It’s definitely the last word in sound reactive lamps. Click through to see [Trent’s] PCB, and the Butt Lamp in action.

Continue reading “The Butt Lamp: Light From Where The Sun Don’t Shine” →

Capacitance Measurement With The Arduino Uno

January 22, 2014 by 25 Comments

CapTestBoard1

Have you ever found the need to measure the capacitance of a capacitor? No multimeter handy (for shame)? Well, as it turns out you can actually measure capacitance using your Arduino Uno, with no external components, and only ~20 lines of code.

[Jonathan Nethercott] does an excellent job explaining a capacitance test circuit which uses a reference capacitor to calculate the unknown capacitance. He further explains that, with the Arduino Uno, you can remove the reference capacitor from the circuit, and simply use the stray capacitance present in the board and microcontroller, which can be calculated. This results in the test circuit being as simple as plugging in your capacitor to pins A0 and A2. Continue reading “Capacitance Measurement With The Arduino Uno” →

Sniffing And Decoding Bluetooth LE Advertising Packets And NRF24L01+ Comms. For Under $30

January 22, 2014 by 9 Comments

[Omri] just documented his journey to sniff and decode the protocol used by the popular NRF24L01+ transceiver off the air for very cheap. As he was designing a mesh network code and needed a way to monitor/debug the overall network performance, [Omri] decided to look for some RF hardware.

We’re sure that most of our readers are familiar with Software Defined Radio (SDR), which not so long ago became popular when some engineer discovered hidden registers inside Realtek RTL2832U chip, allowing many DVB-T dongles to be converted into RF listening devices. Unfortunately for [Omri], most of them have a maximum listening frequency of 2.2GHz, while the NRF24L01+ emits at 2.4GHz. The solution? Buy a 2.2-2.4GHz antenna from Aliexpress with a low-noise block downconverter (LNB), used for a Multichannel Multipoint Distribution Service (MMDS). The LNB therefore takes the 2.2-2.4GHz signal and downconverts it to around 400MHz, allowing any RTL-SDR-compatible DVB-T dongle to listen to the NRF communications. A program was then written to decode the RF signal and output the sniffed data in realtime.

GPS Engagement Ring Box

January 22, 2014 by 17 Comments

gpsEngagementRingBox

[James] got engaged recently, in part thanks to his clever GPS Engagement Ring Box, and he sent us a brief overview of how he brought this project to life. The exterior of the box is rather simple: one button and an LCD. Upon pressing the button, the LCD would indicate how far it needed to be taken to reach a pre-selected destination. After carrying it to the correct location, the box would open, revealing the ring (and a bit of electronics).

Inside is a GPS antenna and a Stellaris Launchpad, which are powered by three Energizer lithium batteries to ensure the box didn’t run out of juice during the walk. To keep the lid closed, [James] 3D printed a small latch and glued it to the top of the box, which is held in place by a micro servo. Once the box reaches its destination, the microcontroller tells the servo to swing out of the way, and the box can then open. As a failsafe, [James] added a reed switch to trigger an interrupt to open the box regardless of location. It seems this was a wise choice, because the GPS was a bit off and the box didn’t think it was in the correct place.

Swing by his blog for more information on the box’s construction and the wiring. We wish [James] the best and look forward seeing his future hacks; perhaps he’ll come up with some clever ones for the wedding like our friend Bill Porter.

Snapchat Person Verification Defeated In <100 Lines Of Code

January 22, 2014 by 53 Comments

out

[Steven Hickson] woke up this morning to an article about the new person verification system Snapchat has implemented. Thirty minutes later he cracked it to be solved by a computer, in less than 100 lines of code (GitHub).

First a little background. About a month ago, 4.6 million Snapchat users had their information compromised by a security hole. In an attempt to bump up security, Snapchat has implemented a new person verification method to ensure new accounts aren’t created by computers.

The method? Picking out a white ghost from a series of nine images. Kind of like a cute, less annoying Captcha. The problem? It’s a terrible way to prove you are a person. It took [Steven] only 30 minutes to write a program that uses simple thresholding, SURF keypoints and FLANN matching to find the ghost. In his tests, he’s found the ghost with 100% accuracy. He also muses that there is an even more efficient way to do it, he was just too lazy to do it.

Nice try Snapchat.

3D Printering: Making A Thing In Autodesk 123D

January 22, 2014 by 27 Comments

printering

In the continuing battle against 3D printers used exclusively for fabricating plastic octopodes and useless trinkets, here’s yet another installment of a Making A Thing tutorial. If you’ve ever wanted to make one single object in multiple 3D design softwares, this is for you.

Previously, we’ve built a ‘thing’ in a few different 3D modeling programs, including:

See that ‘Read more…’ link below? You might want to click that.

Continue reading “3D Printering: Making A Thing In Autodesk 123D” →

Interactive Globe Is Awesome For Google Earth

January 22, 2014 by 27 Comments

projector

Time to brush up on your Portuguese if you want to learn how to build your own interactive globe! Or we guess we could use Google translate…

This project was originally presented at Campus Party 2012: an annual, week-long technology festival running 24 hours a day that features LAN parties, a hackathon, conferences, and more. It all started back in 1997 in Madrid, Spain. Today, there are now Campus Parties being held in Brazil, Colombia, Mexico, the USA, Ecuador, and Germany.

The team that created it—[Araujo, Barmak, Teo, Duprat, and Silva]—has now decided to give back to the community and share a tutorial on how make your very own. The globe uses a short throw projector, a mirror, a series of infrared lights, a modified PS3 Eye camera, and an acrylic dome with projector screen paint on the inside. The touchscreen works by the IR light being reflected off of your hand on contact, which is then picked up by the PS3 Eye camera that has had its IR filter removed.

Unless you can find a suitable acrylic dome, it is, unfortunately, rather expensive to make. They had to have one manufactured. Stick around after the break to see how it works!

Continue reading “Interactive Globe Is Awesome For Google Earth” →