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Registered Member #63
Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425
Dan/EVR, I had this idea a couple of years ago! You've been reading my mind! Argh! hehe
A ferrofluid VU-meter display (or if you really want to go crazy, you could do a whole plane and make a histogram in crappy-windows-media-player-visualisations style =-) inspired me for a few weeks, but I never got acceptable results without the coils underneath getting hot.
If you're considering this, I strongly recommend you have a look at putting the ferrofluid in a sealed clear container, then filling the remaining space with soap/detergenty water (find out what's compatible with your particular ferrofluid/carrier).
My initial experiments were confined to tic-tac boxes (about 4mm in the bottom, the rest filled with a mix of shampoo and water :P). I found that I needed to swing the field both ways otherwise (akin to a ferrite GDT 'walking' over time,) the response of the ferrofluid was diminished.
I think you'll find a big obstacle is keeping the coils underneath cool, and getting them close enough to the fluid.
Even if you're only modulating low frequency/bass, the effect is still very impressive. After I blew a few bipolar transistors, though, I gave up on that one.
edit: Oh, might be worth mentioning. Use a couple of small (ordinary will do) magnets in the centre of each coil. Not only do these act to channel the flux better, they also keep the ferrofluid in place. You demagnetize the magnet after some time, but it keeps the ferrofluid to the bottom of the flask. I never went back to air-cored coils after having a little cylindrical or disc magnet in the centre.
Registered Member #64
Joined: Thu Feb 09 2006, 06:25AM
Location: Southampton, UK
Posts: 68
I sucessfully had ferrofluid 'dancing' to music. unfortunatley no pics tho.
My method was; a coil wound to 8ohms, under a plastic dish. the coil was hooked up to one front channel of my 500w 5.1 Kenwood amp & music played in stereo mode.
I found that the most impressive 'dances' were with trance music (Paul van Dyke, Carl Cox etc) with the volume setting adjusted to very loud. :)
The ferrofluid moved with the main beat and also with the rest of the music (higher pitches too) resulting in a dancing/splashing type motion. I tried with other genres of music too, heavy rock (AC/DC, Iron Maiden etc) which resulted in a big mess.
As carbon rod mentions, heat does build up in the ferrofluid and it dries over time.
Registered Member #63
Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425
Ah - another point about choosing a suitable interstitial filler for your display, Dan: not only does it lower the surface-tension of the ferrofluid allowing you to get longer spikes, but, fingers crossed & touch wood, if the carrier fluid or tetramethylammonium-hydroxide or whatever is insoluble in your filler fluid, the ferrofluid won't get hot, and won't "dry out" or evolve to air... if the carrier starts mixing with your own fluid, however, after a few minutes you'll have some expensive iron filings ;)
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Audio Modulating Ferrofluid
