The First TPU

[EMdevices]

Can somebody locate this paper in pdf format?

It's very interesting and applicable to the TPU since bailing (iron) wire is mentioned in the video, and small fluctuations of magnetic field can have a drastic effect, as the paper mentions.

EM

[gyulasun]

Hi EM,

Here is a link to a paper (which is worth reading in itself) which mentions as a reference #2 the original paper from which you have the first page. It must have been published in the Proceedings of the Royal Society vol. 137, year 1937, page 651.  If so, this publication could be found in science/university libraries even via inter-library services from abroad.

According to this paper http://www.sensorsportal.com/HTML/DIGEST/march_06/P_61.pdf
the effect is a Giant Magneto-impedance effect and possibly this effect must have been observed back in 1936-37.

Of course the original paper would be a good reading for sure.

EDIT:further good links on GMI: http://link.aip.org/link/?JAPIAU/90/6280/1  and http://link.aip.org/link/?APPLAB/77/2737/1

rgds,  Gyula

[EMdevices]

thanks for the links gyulasun.

I've been thinking along the lines of NEGATIVE RESISTANCE OSCILLATORS lately.

Can somebody get excited please !Ã, Ã,  LOLÃ, 

I've also been reading up in my Electronics book about oscillators, negative feedback and the stability criterionÃ,  (phase margin, gain margin, Nyquist plots, etc..)Ã, 

So what am I doing?Ã, Ã, 

I'm trying to purposely create and engineer an unstable system!Ã, 

At this point I don't care where the power comes from.Ã,  I'm engineering the unstable system to self oscillate, and if I can find components that deal with magnetism, so much better.  I'm aiming for no ELECTRONICS.  Just coils, magnets and capacitors.

Now I'm thinking the iron wire and it's resistance succeptability can play right into our hands as a negative oscillator.Ã,  Why?Ã, Ã,  Well because it's so sensitive to an external field.Ã, 

Imagine the flowing current passing through the iron wire also passing through the external helix coil surrounding it.Ã,  Ã,  It will affect it's own resistance.Ã, Ã,  As it increases, the resistance goes up (since the magnetic field increases) but its driven by voltage so in essence we might have a negative slope to the resistance profile.Ã, Ã,  If that doesn't work there's other ways to explore, double balanced coils etc..

just thoughts that I'm currently in love with.

EM

[EMdevices]

This is what I'm thinking.

Could there be a portion of the V-I curve where this exibits a negative slope, hence a negative resisitance that can be used to create an oscillator?

EM

P.S.Ã,  Keep in mind that in the first TPU, the iron wire is in a loop form.Ã,  Also, we can even reverse the iron wire and the copper wire since the fields are such that they work the same.Ã,  (all we need according to the article above is to have an AXIAL magnetic field, which will affect the resitance drasticaly)

Also, recently scientists discovered there is NEGATIVE RESISTANCE at the boundry between magnetic domains (at the microscopic level)Ã, This is encouraging to say the least.Ã,  The reference to the "bailing wire" in the video is starting to look more and more like a vital clue.

[hartiberlin]

Hi EM,
great ideas.
This reminds me of an experiment I still want to do:

Build a coil of insolated iron wire.
As it is iron a permanent magnet will be attracted to the
inside of the iron coil.
Now see, how much inverse current you have to drive into the iron coil
to cancel out the magnetic field attraction, so that the magnet can move through the
coil without being attracted by the coil?s iron.

You could probably also do this by wrapping copper wire around
the iron wire.
Then use the induction voltage from the iron wire to store it in a capacitor
until the magnet has moved into the coil and then use copper wire
around the iron wire to pulse this from the cap to propell the magnet
out of the coil again.
Makes me wonder if you need less energy to propell the magnet out of this special
coil as is produced, when the magnet goes into the coil...

Also from my previous experiments I have seen,
that iron coils don?t produce any Back EMF pulses
and the electrical current heat of the coil is attracted to a permanent magnet sitting on one coil end...