Tesla's "COIL FOR ELECTRO-MAGNETS".

[Farmhand]

Synchro, that's a couple of coils in series on a bent piece of steel. What exactly makes it a PMH ?
It's no different from any old piece of U shaped steel with a couple of coils wound on it.

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[stupify12]

Mags,

I have build the same Bifilar coil into a Tesla Transformer- air core, The effects me and my cousin have seen is when there is load on the secondary coils the Transformer seems to boost its performance and not affected in the so called counter induction. So we tried to add more coils in the Transformer, we have accidentally stumble on it the other secondary is powering a load of bulb with full brightness, accidentally Short circuit the new other Secondary coils that result into a boost of brightness on the bulb being load on the other secondary.

We have tried to make more shorted Bifilar secondary coils on this Transformer it seems to boost its performance with out demanding more power from the input source.


Meow

Also, being that I am running air cores, if I get speed up effects when shorting or loading the bifi, that would be unusual, being that when the coil is open, there is no core to influence the rotor by slowing it down. So why would it speed up loaded? 

Mags

[Farmhand]

Synchro your way off topic, please take the PMH discussion to an appropriate thread and remove any posts about it.

Fairs fair.

[Magluvin]

Mags,

I have build the same Bifilar coil into a Tesla Transformer- air core, The effects me and my cousin have seen is when there is load on the secondary coils the Transformer seems to boost its performance and not affected in the so called counter induction. So we tried to add more coils in the Transformer, we have accidentally stumble on it the other secondary is powering a load of bulb with full brightness, accidentally Short circuit the new other Secondary coils that result into a boost of brightness on the bulb being load on the other secondary.

We have tried to make more shorted Bifilar secondary coils on this Transformer it seems to boost its performance with out demanding more power from the input source.


Meow

Hey Stups

So are you saying,  air core transformer, normal winding primary? Then bifi secondary lights bulb, but how is the input affected?  Then, short another secondary bifi and the light gets brighter on the other bifi secondary??     When that second secondary is shorted, what happens on the primary as compared to no short on second secondary?

Thanks Cat daddyo   

Mags

[Farmhand]

I've have a situation where using the (COIL FOR ELECTRO-MAGNETS) will be useful to me. I'll try to explain in a few words.

I have a HF air core transformer which comprises of two coils one each side of the primary, a (bipolar setup center grounded),
each coil is composed of twenty turns of 2 x 1 mm magnet wire, I had intended to use it with the 2 x 1 mm turns in parallel for
low resistance. However there is spacing string between each 2 x 1 mm wire turn but not between the two wires of each turn
see picture. This means the coils have only 28 uH inductance each and for the experiments I want to carry out I need a higher inductance so that I do not need too much external capacitance, then the only external capacitors I need are one 30 to 1300 pF
parallel plate variable air capacitor on each coil to give me the tuning adjustment I want.

The coils each in series connected configuration should have 112 uH each and with a 30 to 1350 pF variable capacitor I should
be able to tune the LC of the coils to get from the 420 kHz (fundamental frequency of primary) all the way to 5 times that
frequency for experimenting with harmonics.

OK so numbers--

So if the coils in series connected mode = 112 uH then I should need 1280 pF to get them to resonate at 420 kHz.
And if the coils have internal capacitance then I should need less external capacitance than 1280 to get the same effect.
If so the tank current will be less than if I used regular coils with 1280 pF.

I will measure the capacitance between the bifilar windings when they are unconnected.
I will then measure the inductance of the coils to see if there is a reduction from the usual 4 x inductance increase due to
the extra winding. Maybe the spacing affected the usual inductance increase.
Then I'll carefully tune the coils (or one at least) to resonance and power off, disconnect the capacitor and measure the
capacitance required for resonance.

So I'll have the measured inductance, I'll have the required capacitance for resonance and I'll have the capacitance measurement
from before series connecting the windings in the coils.

Then I should be able to use the formula/calculator for L/C resonance to get the required capacitance for resonance and compare
that to the actual external capacitance required. The online L/C resonance calculators have been quite accurate for me in the past.

The benefit in my opinion would be that if less external capacitance is required then the tank current should be less as the
internal capacitance should store it's share of the tanks charge on the coils without causing "tank current".

So if we only require activity in a coil or L/C tank at HF then the "biflar wound" series connected method might be beneficial and
more efficient.

I was also thinking that the energy exchange between the "biflar wound" series connected secondaries and the primary might
be different due to the HV end of the first winding being returned to the bottom near the primary.

Anyway below is a picture of the coils and also a schematic of how I intend to set them up for experimenting with the harmonics.
I am using only 12 volts so far but will employ some kind of voltage boosting arrangement on the input to boost the battery voltage.

P.S. With this setup now having 40 turns on each side secondary I should get a magnificent resonant rise of may times the
transformation rate x the input voltage. Each coil should operate as a 1/4 Wave resonator at the fundamental frequency.

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