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Kinetic glowstick using ferrofluid?

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LAN_403

Conundrum

Sat Oct 18 2008, 08:53PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Hi all.

OK this is pretty far out but might just work.

Having verified that ferrofluid-encased magnets do indeed move with the slightest movement generating power from a correctly wound coil, the next step is to make a plastic or glass closed tube to hold Mr Ferromagnet (tm) and then wind my field coils (split into two connected halves spaced 1/3 and 2/3 along tube to maximise available power) on this tube and secure with Epoxy. Then add Schottky diode rectifiers on the two end coils with the centre tapped to Gnd, connected to a small supercapacitor, which is then connected via a simple constant current circuit using a JFET to the yellow or red LED.

In principle this beastie should glow virtually forever, ignoring coil breakage. The supercapacitor's lifespan should (if you use an aerogel) be unlimited and the LED has a lifetime of over 70,000 hours.

As for switching, I was looking into adding some sort of 1381-based threshold switch so the LED only lit when enough voltage was stored in the supercap (a bit like a BEAM robot) so it wouldn't wreck the supercap, however with LED's this may not be needed as they only draw current above 1.6V or so.

Effect would be a continuous glow which slightly changes as you shake it. If you use an inert fluid such as glycerine or mineral oil and put the glowing LED in the middle with the glass tube held in place at either end with Epoxy or Polymorph, you would get something which resembles a normal lightstick- for extra effect use a UV LED and glow powder if the voltage allows it.

Perhaps this could also be modified to allow a bicycle light to recharge itself when moved :)

regards, -Andre

EEYORE

Sun Oct 19 2008, 06:34AM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

Neato, I like this idea alot! Keep us posted with your progress! Where might I go to buy ferrofluid that will be suitable for this? Im guessing all ferrofluids are not created equal?
Matt

Conundrum

Sun Oct 19 2008, 03:46PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

I got mine from an Ebay seller named scuttlebutt but for some reason I can't find him any more. (might have been because he was also selling chemicals and got Das Boot from the site :( )

and

UPDATE:- Get some element samples from

on ebay and you will find they come in nice screw top sample containers which are ideal for holding the magnets. Add the foam piece from a drinks bottle at the top and bottom, coat the inside with ferrofluid from a cotton bud and it works well. I wound two coils covered with Sellotape but have yet to test it, used electric screwdriver to scramble wind 34ga wire from an old clock using an HDD motor as the spindle to avoid wire snappage.

Might be better to spray coat with varnish as with a TC secondary, should also reduce the chances of a wire break. You might not need the centre tap as the unused coil will act like a resistor if correctly phased.

Pictures to come :)

Inducktion

Fri Sept 20 2013, 02:39AM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

Hey Andre, did you ever get this to work at all?

Proud Mary

Mon Sept 23 2013, 10:51PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Conundrum wrote ...

I got mine from an Ebay seller named scuttlebutt but for some reason I can't find him any more. (might have been because he was also selling chemicals and got Das Boot from the site :( )

Or maybe it's because the seller's name is scuddlebutt, and not scuttlebutt!

Scuddlebutt is still selling ferrofluid on ebay here:

BigBad

Tue Sept 24 2013, 12:08AM

Registered Member #2529 Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 600

I don't quite get it. Wouldn't the ferrofluid magnetically short out the permanent magnet?

klugesmith

Tue Sept 24 2013, 02:48AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1714

Good question, BB.
Last time I checked, ferrofluids saturate at flux densities on the order of 100 milliteslas.
So many permanent magnets would have plenty of energy left over.

If they could make ferrofluid (or even ferroputty) with good permeability to well above 1 tesla,
it could reduce the need for close fitting joints in transformer cores etc.

Connundrum (Andre) --
the link in OP seems to be broken, perhaps from the 2013 migration of fusor.net.
Can you find a new URL and post it here, or edit he OP?

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