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

January 23, 2014 by Adam Fabio 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.

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Color Organ Tiki-o’-lantern

October 31, 2011 by Brian Benchoff 7 Comments

The Halloween parties this weekend are over, but that doesn’t mean there’s not time for a few more to finish a build before children start knocking on doors tonight. [formori] at Lakehead University wanted to do something spectacular for a pumpkin carving contest, so he and a few other EE students came up with a tiki-o’-lantern with music.

The guys at Lakehead figured a color organ flashing LEDs in the eyes and mouth of the tiki would be a very good and easy project. The circuit they used is a simple Op-amp setup like one we’ve seen earlier. The entire pumpkin is powered by a 9 V battery and the music is played with an iPod. There are two colors of LEDs – high frequencies flash a blue LED in the eyes and low frequencies flash a red LED in the mouth.

Aside from the added A/V stuff, [formori]’s pumpkin is one of the best we’ve seen on Hack a Day this year. Check out the Youtube of 1st place winner of the Lakehead pumpkin carving contest after the break.

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Christmasqualizer Is The Next Light Switch Rave

October 15, 2011 by Brian Benchoff 25 Comments

[youtube=http://www.youtube.com/watch?v=la1OuczS_wM&w=470]

[Kyle] was looking for a way to spice up his boring brick-wall dorm room. The Christmasqualizer he came up with brightens up his room and would make an awesome place for a rave.

The strings of lights in [Kyle]’s Christmasqualizer are off-the-shelf Christmas lights. A simple circuit for the 7-band equalizer was built following this article. The build uses an MSGEQ7 equalizer chip takes audio from any source. The volume level of the seven EQ bands are output to an Arduino over a serial connection.

After the EQ chip was connected to the Arduino, [Kyle] needed a way to switch the strings of Christmas lights on and off. A few solid state relays later, and he was in business.

All the code for the Christmasqualizer is up on github. The sketch is pretty simple – connect the EQ chip as per the article, then connect the relays to the output pins on the Arduino. It’s a fun and easy project that really livens up a dorm room.

Guitar Becomes An Improved Color Organ

July 24, 2011 by Brian Benchoff 12 Comments

[Charles] wanted to put some LEDs in his guitar. He also wanted individual notes to output certain colors, but he couldn’t find any projects with tone-based algorithms to convert sound into colors. After about a year of work, his ColorChord guitar was born.

Unlike every other color organ build we’ve seen, the color of a note does not relate to the absolute pitch of the note. Instead, the colors are mapped within a musical key. A I chord will always be Yellow, a IV chord will always be purple, and a V chord will always be blue. Playing in the key of C will have the LEDs output yellow, purple, and blue for a C, F and G chord, respectively.

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DIY Lightning Special Effects

February 26, 2011 by Chris Nelson 3 Comments

Halloween may have come and gone but thats no reason not to take a look at this neat little special effects setup. Basically it uses an analogue circuit to monitor an audio signal and triggers some camera flashes using 5V relays. The idea is that you can play lightning strikes and other spooky sounds, and the system will trigger camera flashes to coincide with the lightning strikes. Adding in some color organs in addition to the camera flashes will dim your lights to help achieve a thunder like effect. Unfortunately there aren’t any schematics for the color organs (which technically might be just light organs) but that doesn’t detract from the seemingly well designed analogue signal processing. Check it out in action after the break.

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