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Audio Modulating Ferrofluid

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LAN_403

HV Enthusiast

Tue Feb 21 2006, 07:24PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

I've been interested in this project for about two years, but really haven't had time to pursue it seriously. Anyways, what i had proposed before was designing an audio modulated ferrofluid display which would be sychronized with music.

However, one of the biggest concerns would be frequency response of the ferrofluid itself. Even if modulated to only the "bass" frequencies (i.e. <100Hz), would the ferrofluid be able to respond fast enough.

Ferrosound has a wide variety of ferrofluids with various viscosities, where i would assume viscosity (as well as volume) would be proportional to frequency response.

Anyways, just curious if anyone has already explored this route and/or has any ideas / thoughts. Seems like it would be a pretty cool project if it could be made to work.

Marko

Tue Feb 21 2006, 07:28PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

It can be modulated and form interesting movements but i doubt it could make, especially high frequency sound (maybe could but on poor quality)
I never stuck my hands with some ferrofluid but it seems hard to make it 'jump' without large disortions at fer khz...

HV Enthusiast

Tue Feb 21 2006, 08:19PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

The ferrofluid obviously wouldn't be used to produce audio. It would be modulated for motion only.

Marko

Tue Feb 21 2006, 08:33PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Confusion from your first post...

I see no reason why should not it be possible then

HV Enthusiast

Tue Feb 21 2006, 08:35PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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Posts: 3068

The frequency response of the liquid will probably be an issue, even for low frequencies, especially if using a relatively large volume.

Sulaiman

Tue Feb 21 2006, 09:26PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

I know nuts about ferrofluid...but...

could you produce slightly different grades/sizes of particle,
each size dyed/pigmented a different colour
there MAY be some rippling-colour effects due to
the different size particles in the fluid rotating/accelerating at different speeds in an audio modulated magnetic field?

no idea if that's a load of ...

P.S. Since you like quizes..

Imagine two Helmholtz coils N-S and E-W
with a dish of ferrofluid in the middle
Left audio to N-S coils
Right audio to E-W coils

What patterns would you see in the ferrofluid?

(Inspired by left to X axis and right to Y axis using 'scope)

P.P.S.
How about a feffofluid DLP?
Bounce a bright light off the feffofluid onto ceiling etc.
Use a lens or shaving mirror for focussing.

Via cross-polarised filters????

------OR---------
How many tiny electromagnets would you be able/willing to make
as an array of 'pixel' activators?

Carbon_Rod

Tue Feb 21 2006, 09:36PM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

A few issues to consider:
1.) The fluid suspension may undergo heating thus lowering the viscosity. Perhaps mixing the suspension with an oil or solvent may lower its viscosity further.
2.) The driving frequency will simply integrate any details and or starve to antinodes at some frequencies.
3.) The human eye will not "See" those frequency changes anyways.
4.) How about direct modulating a rectified 60 Hz signal or lower to an electromagnet (or is it 50Hz down under)? You would get horrible beat frequencies forming, but it is cheap to build and may look pretty cool.

Madgyver

Tue Feb 21 2006, 09:55PM

Registered Member #177 Joined: Wed Feb 15 2006, 02:16PM
Location: Munich, Germany
Posts: 214

Why not just couple a strong ele. magnet to a music visualizer? A simple example would be one of those Bargraphs, which jump up and down.

Sulaiman

Tue Feb 21 2006, 09:58PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

I assume only the lower audio range will be useful
so rectification of the audio may be good (full/half-wave)
with many turns of thin wire until Rdc = 4/8 Ohms.

These coils can also be fed audio directly
to turn dry leaves/paper etc. with a tiny NdFeB magnet stuck on
into audio transducers.
(Crappy but fun loudspeakers, really is fun - try it)
(Contest for best sounding dried fruit/vegetable anyone?)

P.S. In playing with coils driven by audio amplifiers
I found that there is some optimisation required for the coils,
for me it ended up with MORE WIRE = BETTER.
a small coil with many thin turns wasn't as good as a big coil with thick wire when both have the same dc resistance.
Never bothered with the math.

Tesladownunder

Tue Feb 21 2006, 10:35PM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

Well, I have a container of ferrofluid and an accumulating list of things I must do with it. There goes my weekend..

Pics soon

Peter

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