Bismuth core Joule thief

[resonanceman]

Gary:

I was talking about a core material, not for primary winding.

Bismuth can be easily obtained from shotgun shells, just be careful unloading them if they are live.  The pellets are bismuth instead of lead.  I read this somewhere on the net.

Bill

Bill
Yes you clearly were talking  about  bismuth as a core material.

I was thinking along wider lines.

If  others here want this to  be  only  about bismuth cores I will keep to myself  about other possibility's.

I am thinking  if it is usable  at all  for cores......it is probably great for  other things ....... I can't explain  why I think this.... you could call it intuition.

gary

Edit

thanks  for  the information on  shotgun shells...... a quick  search shows that some of them but not all of them are a bismuth alloy

Nearly pure bismuth  can  be found  on ebay for a little over $15 a pound    I am not  sure  yet if this is a good price or not.

[resonanceman]

Given  the low melting point of bismuth  it should be very easy to make a crude core.

supplys

a little  bit  of good quality car wax as mold release

A short  section of  plastic  pipe  or something else to act as a  ridgid support   on the outside of the mold.

A tube of silicone rubber.

A toroid  or  toroid  shaped  material of the right size.  ( a wax toroid  would not need mold release )

A small metal bowl stainless  would  be ideal.
a metal  measuring spoon  might  be good enough for a small core.

A blowtorch

pliers or visegrips for  holding on to the  metal bowl while heating and pouring.



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I  would  start  by  putting  a nice even layer  of silicone rubber in the short section of  plastic  tube  as a " floor "  for the toroid .

I would  get this first layer  as level as I could then  let it sit a few days to cure.

The outer tube should   be  cut to  be even   with the  toroid plus the  floor .

I would then  put a  coating of car wax over the  toroid .......  It might  be a good idea to test  a few samples first to make sure the that particular wax will  be an effective mold  release with for silicone rubber.

next I would  fill  the  mold to be  with silicone rubber........then place the  waxed up  toroid into the center  of the whole works.
I would then use  a  straight edge  of some kind to scrape  off the excess silicone rubber so that the top  of the toroid is right at  the surface.

I would  give it a week or so  to cure.............then  press on the underside to pop  the toroid  out.

A blowtorch  and a small metal bowl of some kind should  be all that is needed to melt the  bismuth.

once the bismuth  is melted  pour it into the  mold  .......let it cool....then pop it out.


gary

[Pirate88179]

For those that want to learn about bismuth, this video is done by a cool professor who has a series of videos.  Here is the one on bismuth:

http://www.youtube.com/watch?v=vyIo-c7VmIM&feature=related


It is radioactive and emits alpha particles, which I did not know.  It is considered meta-stable however.

Bill

***EDIT***      I went back and watched the posted video again and it is weird.  The old professor says it is the heaviest metal on the elements chart that is NOT radioactive and yet his lab assistant says they discovered 5 years ago that it is.  It sounds like it is very, very low level and she was holding a crystal form of it in her hand and was not concerned so it must not be any big deal.

[WilbyInebriated]

bismuth and stubblefield...

[Mk1]

@wilby

You got it , just imagine a 3 layer sandwich bismuth (modified to be  a solid electrolyte) so it could be aluminum /bismuth (electrolyte/reactor)/ carbon plate turned into a coil think tpu size coil , then put a coil around it(secondary) and a switching device on the coil to kick it.