[Kelvie1234]

So would using extra batteries be completely useless, even if I put them im parallel? (also do I have to match the voltages?)

I'm thinking the more current I can get through it, the more quarters it'll pick up.

And with more power in lightweight batteries, I can win the most quarters... and highest (mass) efficiency.

I was also reading up on superconductors a while back.. although not feasible

I'm going to probably stick it in the freezer.. and bring it in a big ice box.

 

[amisdad]

I cant beleive nobody has mentioned Lithium Polymer Batteries. Lithium Ion is junk technology. LiPos are smaller and lighter LiPo cells have a lower internal resistance, so they're able to provide higher amp draw. Individual LiPo cells have a nominal voltage of 3.7 volts (vs. 1.2volts per cell for Ni-Cds). Cells are wired in series to give the following pack voltages: 1 cell = 3.7 volts 2 cells in series = 7.4 volts 3 cells in series = 11.1 volts. You often see these cell's wired in series and parallel together. A battery pack that has three cells in series (giving 11.1 volts) and 2 of these 3-cell packs are wired in parallel is commonly referred to as a 3S, 2P (3 series, 2 parallel). These cells can discharge at about 20 amps no prob.

 

[kevin gilmore]

quote
I was also reading up on superconductors a while back.. although not feasible

Sure it is feasible. Depends on how creative you are.
Besides which, once charged it needs no current whatsoever.
This will pick up a whole lot of quarters. Several hundred
killograms worth.

Here are some neat pictures of the insides of one of my
cryomagnets...

http://www.jeol.com/nmr/mag_view/mag...struction.html

 

[jamont]

Quote:

Originally posted by kevin gilmore Sure it is feasible. Depends on how creative you are. Besides which, once charged it needs no current whatsoever. This will pick up a whole lot of quarters. Several hundred killograms worth. Here are some neat pictures of the insides of one of my cryomagnets... http://www.jeol.com/nmr/mag_view/mag...struction.html

Very cool

Just curious, have you ever seen one of these things quench?

 

[kevin gilmore]

quote
Just curious, have you ever seen one of these things quench?

I quenched a 500 about 2 months ago charging it
for the first time.

A 400 quenched in december.

I deliberately quenched a 400 last week.

Really impressive especially when you can hit the
mains heater button and get it to quench on command.
Scares the crap out of people who have not seen it
before.

About 100 liters of helium liquid turn into gas very
quickly and exit the 1 inch safety hole at about
200 miles per hour. Sounds very similar to standing
next to a steam engine that is starting at full blast from
a dead stop. Actually louder than that.

 

[groggory]

wow kevin, that is seriously impressive

Plus the "This magnet contains approximately 12 miles (19 km) of superconducting wire." "dissipating the heat generated from the 85.5 kJ of energy that is stored in the energized magnet"

Those little specs in themselves show the sheer enormity of these experiments

 

[Kelvie1234]

Hmm... they dumbed down the voltage to 6V, with an unknown current.

Would it be a good idea to go out and spend on a few lith. polymer batteries to get it up to 6V.. then create a circuit that would put it in parallel with the supplied 6V charge?

Or would that fry the batteries?

And I think I'm going with the "horseshoe magnet" idea.. where both poles are doing the picking up. I'll probably stop by a metal supply shop, or an auto body shop and see what kind of metal they can shape me up.

Also with that.. how would I design that "guide" for the horseshoe magnet?

And I'm lost at finding the right wire.. what's the thinnest gauge wire (magnet wire?) at digikey? Also it has to have extremely thin insulation too.

Thanks again,

 

[Kelvie1234]

Well.. alright.

I got some 30 gauge magnet wire from the RatShack.

A few problems remain..

I don't know where to get an iron rod. I was thinking to get a 4cm diameter 30cm length iron rod (preferably the 49 Iron-Nickel Alloy composite), bent into a U shape; but I do not know of any places to get this in such short time (most places don't open on weekends either). Is a steel rod good enough? Or is it no good at all?

Also.. the magnet wire. I have two rolls of 200'. I don't know if that's enough, and connecting them together will be a problem.

How is it to be stripped? I'll have to hook up 30cm long leads to hook up to the power supply also.. and it seems tough hooking up regular hookup wire to 30g magnet wire.

And last thing, is it worth it to have the core hollowed?

(note: 2.54cm = 1 inch.. for those that don't use metric )

 

[groggory]

I don't know if you've ever used magnet wire before, but it doesn't have traditional insulation. It has a sort of oxidized (or something similar) coating. You can 'strip' this coating off with a cigarette lighter. Just make sure that whatever gauge magnet wire you choose, it can handle the currents your planning on using.

 

[Born2bwire]

In relation to what Groggory was saying, you would want a solid core.

Using a solenoid as an example of a core of air, your magnetic flux density would only be proportional to the magnetic permeability, the number of loops per unit length, and the magnitude of the current (B = unI). By inserting a core into the solenoid, you now make the magnetic flux density through the metallic core proportional to current and the magnetization of the metal (B = u(nI+M). Plus if you could choose a material to have a magnetic permeability that is greater than that of freespace as another way of boosting the magnetic flux.

Really I think just doing a horeshoe magnet out of a iron rod would work. Just wrap it tightly with thin wire and put a high current through it and that should do fine. You were mentioning that you were having trouble finding material, what about a piece of rebar... though that's steel.