Making real-life portals with a Kinect

[radicade] wanted to know what real life portals would look like; not something out of a game, but actual blue and orange portals on his living room wall. Short of building a portal gun, the only option available to [radicade] was simulating a pair of portals with a Kinect and a projector.

One of the more interesting properties of portals is the ability to see through to the other side – you can look through the blue portal and see the world from the orange portal’s vantage point. [radicade] simulated the perspective of a portal using the head-tracking capabilities of a Kinect.

The Kinect grabs the depth map of a room, and calculates what peering through a portal would look like. This virtual scene is projected onto a wall behind the Kinect, creating the illusion of real-life orange and blue portals.

We’ve seen this kind of pseudo-3D, head tracking display before (1, 2), so it’s no surprise the 3D illusion of portals would carry over to a projected 3D display. You can check out [radicade]‘s portal demo video after the break.

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DIY spring and plate reverb

If you’re running your own recording studio, you’re going to need a lot of gear that seems excessively esoteric to the non-musically inclined. A rack full of synth gear looks just like any other cabinet of technology you would find in a server room. Electronic music is, for the most part, very utilitarian looking, but there are a few pieces that add a very nice aesthetic touch to any studio. [Peter] made two great looking pieces of hardware – both reverbs – that significantly add to the decor of his studio. As a bonus, they also sound really good.

[Peter]‘s spring reverb (Dutch, Google translate) works just the same as any other spring reverb; a speaker puts some music into a slightly stretched spring, and this sound is picked up by another transducer at the opposite end. For this build, [Peter] used a Slinky and a piece of PVC pipe left over from a bathroom remodel. Adding a few jacks, pots, and a preamp, [Peter] had a very nice and extremely large spring reverb.

The plate reverb (translation) is also a staple of pro recording studios around the globe. This reverb is somewhat similar to a spring reverb, except the spring is replaced with a tuned metal plate. [Peter] used a cymbal from a drum set for this piece of kit. Two speakers are attached to the back of the cymbal, one feeds a sound into the cymbal, the other speaker picks up those sounds and sends it to the mixing board.

There’s a lot of really cool musical DIY projects over on [Peter]‘s site, along with a few audio demos for each of his DIY projects. We’ve included his reverb demos after the break, feel free to give those a listen.

Thanks go to [geekabit] for sending this one in.

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Geeks living off the grid are hard on batteries

Many of you will remember [Mikey Sklar] from the multitude of times he’s been on hackaday. What you may not have noticed is that he is an ubergeek, living off the grid.

He has Solar PV battery bank, three electric vehicles, a shipping container loaded with battery powered tools and a small army of iRobot Roomba’s for cleaning. Getting the maximum lifetime out of a battery by removing sulfation is essential to keep expenses down.

Keeping expenses down is nearly a full time job when trying to live the homestead lifestyle. Our current culture makes it extremely difficult to survive completely on self made/grown things and bartering. They seem to be doing pretty well though. One way he can reduce his costs while still getting to enjoy some modern gadgets is to get longer life out of his batteries.  He does this by using a capacitive battery charger and desolfator that he designed and affectionately calls “Da Pimp”. He also brings in a little bit of income by selling kits!

 A capacitive charger behaves like a constant current power supply dynamically adjusting the voltage to get over the batteries internal resistance. Plus there is a pulse from the AC/DC conversion. This allows for old batteries to last longer and for dumpster dived to be used as replacements. Capacitive chargers are small, silent and super efficent (up to 60% more so than cheap transformer based chargers).

Of course, [Mikey] is a supporter of sharing information so you can also go to his site and download the schematics,bill of materials, gerber files, and files for the housing,  to build one yourself.

Building a color sensor using luminosity

[Richard Osgood] is back again with an interesting project. This time he has constructed a color sensor. His initial design was to use three LEDs and a photoresistor. He would shine a red, then green, then blue LED on a surface and record the reflected light with the photoresistor allowing him to determine how much reflected light there was of each color. Unfortunately, he found it to be completely unreliable. An attempt at using a light frequency sensor didn’t work either. What did finally work, was a luminosity sensor shown above.

Finally, his prototype worked. Unfortunately only the red LED gives readings that he considers to be adequate with the blue and green being “not all quite right”.  With this type of circuit, he could build a clone of the magic chameleon lamp.

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