Tesla's "COIL FOR ELECTRO-MAGNETS".

[fritz]

Flat copper strips make good coil conductors in some applications.

Using flat foil coils is pretty standard in switched mode powersupplies.
To increase the coupling and prevent stray flux, the primary might be split in multiple parts, surrounding the secondaries.

rgds.

[Farmhand]

Hi Fritz, I've noticed in some appliances like televisions and such that some small HF transformers have a wide copper band around the wire windings, the copper band is soldered as a band like a shield. Wouldn't that reduce the inductance kinda like a shorted winding on a multi-strand coil ? I think I've been told it's for shielding from memory.

Anyway when I wound my second motor coil, I had to use a slightly different former with a slightly bigger core so the coil has more inductance than the other one so to keep the same DC resistance I just wound some "extra other" wire around it and soldered that extra wire "shorted" which lowers the inductance of the coil a bit. It could do with a bit more yet. It's not important though because it's just a rough test setup.

Hmmm Just thinking. 

I'm guessing that a coil wound from iron or steel wire would have lots of inductance compared to the same length of copper wire with no ferrous core.

What about aluminium wire ? Will it yield the same inductance (with a steel core) as a copper coil would for the wire length and diameter (with a steel core) or is mass a factor ?

To all:  Anyone know of a source of about 0.5 mm to 1 mm or so insulated aluminium wire for magnets ? Or even stranded thinly insulated aluminium wire ?

CHeers

[synchro1]

Pancake Magnetizers are a still in use:

"To test the device, we generated a magnetic field using a "PANCAKE-TYPE MAGNETIZER" and a cracked magnetized ferromagnetic specimen and imaged the vectors".

http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6332808&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6332808


I came across this, I found to be very interesting about the coil's properties:

"It is well known that the inductance of a pancake type coil put on the metallic specimen changes according to the electromagnetic properties of the metallic specimen"

[synchro1]

This might help stifle the hysteria,

From: Electromagnetic pulse generator plans:

"Pancake coils are perfect for the job".

"If you want true emp pulses, you would need to do a little research. Combining a high frequency pulsing circuit that pushing a good amount of current into pancake coils. Look up Nikola Tesla and Pancake coils to see what I mean. It is my opinion that you would not want any ferrite in any of the coils if you expect the electromagnetic field to disipate in the surrounding air either. Pancake coils are perfect for the job. Maybe a nice stack of them, and you will kick a pulse directional much stronger than firing a nail through a coil of wire with dynamite. Not to mention, you might survive when you fire it off".

The issue is; What are this coil's special applications? I think I've built a sufficient case so far to prove that the pancake bifilar coil's used as an "Impulse Magnetizer"!  Alright?

                                             " we generated a magnetic field using a "PANCAKE-TYPE MAGNETIZER"!

The question remains, how do Skycollection's ferrite toroids react when pulsed from a stack of these kinds of magnetizer pancacke coils?

[fritz]

Hi Fritz, I've noticed in some appliances like televisions and such that some small HF transformers have a wide copper band around the wire windings, the copper band is soldered as a band like a shield. Wouldn't that reduce the inductance kinda like a shorted winding on a multi-strand coil ? I think I've been told it's for shielding from memory.

There are shielding layers with ferrite transducers, typicalwise between primary and secondary, foil type, with just one end connected to protective ground.
The idea behind is that in case of extreme overvoltage - the discharge should happen toward protective ground. In this case the foil is just a cap - not a single turn.

I´ve seen what you mean - I think this is used for non-flyback situations with ferrite and metal cores, reduces stray flux and works as kind of base loading to keep (iron) losses down / if no secondary load.

I'm guessing that a coil wound from iron or steel wire would have lots of inductance compared to the same length of copper wire with no ferrous core.

What about aluminium wire ? Will it yield the same inductance (with a steel core) as a copper coil would for the wire length and diameter (with a steel core) or is mass a factor ?

To all:  Anyone know of a source of about 0.5 mm to 1 mm or so insulated aluminium wire for magnets ? Or even stranded thinly insulated aluminium wire ?

CHeers

I would expect only small difference between steel, copper, al wire in terms of inductivity.
The major difference would be the resistance. Stanley Meyer uses SS resistive wire for his pulse transformers...
If you have lots of turns and thin and long wire - the resistance will give you somewhat completly different.


rgds.