A year ago or so I started tinkering with a special design of coil wrapped around two
separate ferrite core. The idea was to create a counter rotating magnetic field. One
field would be in the center core, the other would be the outer core. Here is a picture of the coil. Now its hard to see how its constructed but here is a description;
The wire is actually desoldering braid laid flat against the cores, I chose
this material because Tesla had mentioned that using flat copper cable would not heat
up like round cable would. So the coil is wound in caduceus style meaning the first wrap
goes around the outer core then its counter wrapped in the inner core. When you pulse
the coil with DC what happens is you create a magnetic field say N/S on the outer core
and S/N on the inner core as close together as possible to each other.
Now when I drove this coil in the high frequency range of around 45khz with a overdrivin
Sine wave into an audio amplifier something strange happened. It started to emit a high
frequency squeal that did not show up on the scope as noise in the signal. Mind you
that 45khz is way too high to hear and I thought that it may be a harmonic of the driving
frequency but it did not show up on the scope even by using a probe hooked up to a separate
coil wrapped around a core so that I could see any stray voltages.
After a few minutes of this noise all of the sudden I heard a Pop. Looking at the core
I noticed that both cores had exploded. So after winding another setup, I repeated
the test again. Same result, ringing then boom another set of cores destroyed themselves.
Come to find out it was because of a phenomenon called Ferromagnetic resonance
I had only one set of cores left so knowing that I didn't want to blow these up I moved on
to find out what else could be done with them.
I put the coil aside until today when I had the chance to experiment again. After hooking
up the coil as you see in the picture, I sent a 12vdc Pulse into it with around 500ma, Here is a picture of the driving current and frequency and Here is a picture of the O-scope showing the output voltage and
wave form. Now I don't know about you but that is a very high voltage coming from a very short
coil winding. When I touched the output where the scope probe is with my finger It burned like
it was red hot, but when I cut the power to the coil and touched the wire it was room temp. I am
driving the coil with a 555 timer circuit with adjustable frequency and duty cycle feeding a Mosfet.
The voltage will go higher when adjusted but my scope OL's over 600v. So for the pic I dropped
it to show the voltage. The black wire coming from the mosfet is connected on one end and the
other lead is connected only a few turns in then the output is taken from the other end of the coil.
Here is one more picture of the coil connected to one end of a florescent bulb.
I wanted to share my findings so others may duplicate and further the cause. Good luck.
separate ferrite core. The idea was to create a counter rotating magnetic field. One
field would be in the center core, the other would be the outer core. Here is a picture of the coil. Now its hard to see how its constructed but here is a description;
The wire is actually desoldering braid laid flat against the cores, I chose
this material because Tesla had mentioned that using flat copper cable would not heat
up like round cable would. So the coil is wound in caduceus style meaning the first wrap
goes around the outer core then its counter wrapped in the inner core. When you pulse
the coil with DC what happens is you create a magnetic field say N/S on the outer core
and S/N on the inner core as close together as possible to each other.
Now when I drove this coil in the high frequency range of around 45khz with a overdrivin
Sine wave into an audio amplifier something strange happened. It started to emit a high
frequency squeal that did not show up on the scope as noise in the signal. Mind you
that 45khz is way too high to hear and I thought that it may be a harmonic of the driving
frequency but it did not show up on the scope even by using a probe hooked up to a separate
coil wrapped around a core so that I could see any stray voltages.
After a few minutes of this noise all of the sudden I heard a Pop. Looking at the core
I noticed that both cores had exploded. So after winding another setup, I repeated
the test again. Same result, ringing then boom another set of cores destroyed themselves.
Come to find out it was because of a phenomenon called Ferromagnetic resonance
I had only one set of cores left so knowing that I didn't want to blow these up I moved on
to find out what else could be done with them.
I put the coil aside until today when I had the chance to experiment again. After hooking
up the coil as you see in the picture, I sent a 12vdc Pulse into it with around 500ma, Here is a picture of the driving current and frequency and Here is a picture of the O-scope showing the output voltage and
wave form. Now I don't know about you but that is a very high voltage coming from a very short
coil winding. When I touched the output where the scope probe is with my finger It burned like
it was red hot, but when I cut the power to the coil and touched the wire it was room temp. I am
driving the coil with a 555 timer circuit with adjustable frequency and duty cycle feeding a Mosfet.
The voltage will go higher when adjusted but my scope OL's over 600v. So for the pic I dropped
it to show the voltage. The black wire coming from the mosfet is connected on one end and the
other lead is connected only a few turns in then the output is taken from the other end of the coil.
Here is one more picture of the coil connected to one end of a florescent bulb.
I wanted to share my findings so others may duplicate and further the cause. Good luck.