This hack isn’t really all that, but I’m giving it points for creativity. [Christopher] pulled some blue led case fans and used them to make a giant VU meter. Each I/O line has a transistor to drive a TIP120 FET. Personally, I’ll like to see even more of them stacked end to end and pulling fog from a conduit placed behind the stack.
Just for the record: the tip120 is a bipolar darlington, not a FET.
Posted at 2:09 am on Aug 17th, 2007 by println
i dont get the fans either.
Posted at 8:18 am on Aug 17th, 2007 by agent420
@1,2
“I used the fans initially mainly for the bright LEDs they contain, but I later decided I liked the fan effects, particularly in the upper two fans, which aren’t triggered as often as the bottom three.”
Posted at 9:04 am on Aug 17th, 2007 by Lambda_drive
Thanks for the comments, guys. Yes, I originally used them for the bright blue LEDs; I left them in the casings because they form pretty effective diffusion lenses. After I powered it up and used it for a while, I noticed that various songs would get the fans spinning at various speeds due to the beat, and the resulting pseudo-pulse-width modulation intrigued me.
Posted at 9:46 am on Aug 17th, 2007 by Christopher Mitchell
Awesome, +10 respect points for using Damn It Feels Good to Be A Gangsta from Office Space!
Putting them in a big sealed tube with some fog could be interesting though, as Will suggested.
Posted at 10:31 am on Aug 17th, 2007 by wraith
Cool. I’ve used Discolitez before. Why did you not use the full 8 channels that you can drive off the parallel port? Also, use the Pro verion of Discolitez. It is insane what you can do with it. You clearly have the whits about you to get the first 5 channels going. Finish the other 3, and or grab the other shift register circuit and start inching towards 32! Set up 4 towers of 8 fans each. Now you got some air swirlin’ led blazin’ action!
Posted at 11:41 am on Aug 17th, 2007 by Buzzkill
@1: I wanted the future possibilities of running patterns on the array while no music is playing
@5: Thanks, I also like will’s idea
@6: I limited it to 5 because of the number of fans I had on hand. If I can get more fans, I’d love to expand it. I’d probably use Strobe and Auto Feed to do the multiplexing, something like that. I’d also be very interested, if I can find 5 or 11 more fans, to put a second column on the other side of the pole so I can do left and right visualization independently.
Posted at 12:44 pm on Aug 17th, 2007 by Christopher Mitchell
At the very least, put some metallic streamers on the fans so you can see the the fans revving up. Well done!
Posted at 1:03 pm on Aug 17th, 2007 by ChiTownJerry
You could eliminate the need for the PC all together if you used something like a LM4970.
http://www.national.com/pf/LM/LM4970.html
Posted at 3:16 pm on Aug 17th, 2007 by Chupa
That was so rad man. I wish that I could make one of those. For reals, that is going to be on the next rap video yo.
Posted at 5:54 pm on Aug 17th, 2007 by nathan belomy
@8: Interesting idea.
@9: Thanks 
@6 again: Checked out DiscoLitez2 Pro, it’s seriously amazing. I’m definitely considering finding or buying more fans and expanding this more now.
Posted at 6:26 pm on Aug 17th, 2007 by Christopher Mitchell
TIP120’s are darlington pair NPN transistors not FETs.
Posted at 7:15 pm on Aug 17th, 2007 by neil
the german project blinkenlights has done this already with leds and even lights in buildings.
just two weeks ago at the CCC camp there were two HUGE light vumeters (about 3m high, 1m diameter) out of the concert hangar.
nice hack anyway. yes i thought it was cool. make it bigger
Posted at 5:43 am on Aug 18th, 2007 by jaromil
Actually, I was thinking ping-pong balls on the suggestions of several of my colleagues.
Posted at 10:48 am on Aug 19th, 2007 by Christopher Mitchell
10 points using Nightwish,
I think fog would be an amazing idea, also maybe some lazers?
Posted at 3:53 pm on Aug 19th, 2007 by mad_cow
Will repeatedly revving the fans up and down kill the motors eventually?
Posted at 7:11 pm on Aug 19th, 2007 by Vladsinger
@ #15 - the amount of wear would be miniscule and would come from the brushes in the motor wearing (if it even has brushes). I would think that lower revolutions would increase longevity but I think would use more power.
@Creator - Awesome dude, please keep us posted!!
Posted at 1:02 am on Aug 20th, 2007 by Guitar Maniac
These fans actually would be a lot like rotary speakers - speakers designed for the 0-60hz range.
Of course they represent a higher range of sound… interesting
Posted at 9:03 am on Aug 21st, 2007 by srilyk
They’re brushless case fans, so I doubt that wear and tear will be much of a problem. So far I reconfigured it to use all 7 fans for the visualization, with the two multicolor ones at the top. I’m looking into lasers, fog, etc etc.
Posted at 9:18 am on Aug 21st, 2007 by Christopher Mitchell
Interesting work, check this out, it may inspire you to take things further: http://www.uva.co.uk/wp/wp-content/projects/volume/volume.mp4
Posted at 7:00 pm on Aug 22nd, 2007 by AJ
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I don’t think I understand why he used fans… still an interesting approach. I would have used a diode ladder to control the transistors so it could be driven by any analogue audio signal.
Posted at 1:03 am on Aug 17th, 2007 by ex-parrot