Tesla's "COIL FOR ELECTRO-MAGNETS".

[MileHigh]

Farmhand:

I do understand what you are saying in a layman's way, and I have read that series resonance means no resistance and parallel resonance means infinite resistance, but I don't buy it. Simply because if a condition of parallel resonance actually meant infinite resistance we would never see it because it would be impossible, unattainable.

You will recall that TK recently did the coil resonance tests.  If you look at Itsusable's videos he also did some coil resonance tests several months ago.  You have the signal generator output going to the resistor going to the coil.  When you hit the coil's self-resonance point you see maximum amplitude across the coil.  So what does that suggest?  There is a part of that test that I haven't seen done to my recollection.  That's to check the voltage across the resistor.  When you think about it, checking the voltage across the resistor is telling you how much current is flowing through the coil at resonance.  Sounds like a good test but you have to use a real sine wave.

What it suggests is that if you have maximum voltage across the coil at resonance, then the coil is sustaining the most or all of the voltage drop from the signal source.  Therefore you would expect that very little or none of the voltage drop will be sustained across the resistor.  Therefore just from the fact that you know the signal generator is producing a sine wave and the self-resonating coil is producing a similar sine wave, you can conclude that the LC resonator is at maximum impedance.  i.e.; it's acting like a parallel LC resonator at very high impedance and blocking the current flow.  You are welcome to check for yourself.

What that means is that in parallel LC resonance the LC resonator is meeting the driving signal source volt for volt.  The signal source wants to put out 3 volts, and the LC resonator is also putting out 3 volts.  So the LC resonator is "pushing back" against the signal generator and no current flows.

Now, is this happening on your bench in your setup?  I don't know and I am not sure which schematic or configuration you are using today, etc, etc.  But if you do the basic test and confirm what I say, that would be interesting.  To be more practical, I can suggest that you try it with a real parallel LC resonator also.  At resonance you should see zero or near-zero current flow.

Then hopefully you can apply this knowledge to what you are doing.   The first thing that comes to mind is that if you put a resistive load in parallel with a parallel LC resonator, and feed it power from a signal generator through a resistor, will that actually give you some advantages in driving a resistive load across the LC resonator.  You know the LC resonator will get "charged up" from your signal source until it meets the voltage of the signal source, so if you add a "power drain" resistor across it, is that conducive to good energy transfer?  Sort of like can you take lemons and turn them into lemonade.

MileHigh

[Farmhand]

Yes well that may be true for a resonator with no load and the impedance is not infinite except the load voltage and phase matches the supply. What then happens when the secondary is loaded and energy is removed from the system ?

The very technical words and the skirting the issues does not concern me.

If the circuit was tuned to resonance before the supply was connected then in the first instant the primary is energized the supply faces no such impedance. True?

And generally speaking a Tesla transformer has the primary coil tuned to a slightly lower frequency than the secondary because the secondary resonance frequency drops when loaded.  Then the secondary resonance frequency better matches the primary and energy is cast out of the system quite quickly. But it keeps on drawing power from the supply or it would not work.

This coil below won't work like that unless the primary is tuned to resonance frequency just a tad lower than the secondary resonance frequency (unloaded). Input is about 250 to 480 Watts 


http://www.youtube.com/watch?v=1nkJtrKCdFg


Cheers

P.S. Technically you are probably correct but, to the layman or the intuitive experimenter it doesn't matter that much as long as we understand what is going on. We do that by doing and observing. If the impedance is maximum then that is a lot different to infinite.

My Tesla coil primary is only shunted by the primary capacitors when the spark gap fires, when the gap is not conducting the primary has no capacitors. 

..

[MileHigh]

Magluvin:

You are talking about a normal coil. You ignore what Tesla, TK(above) and I have been saying about the bifi coil. You just revert back to there is only inductance in the coil. You deny that anything is different in the bifi coil, yet never built one nor tested one as I read it.

Well if you can restate what's different and show some test results from past or current experiments that would be great.  I discussed these coils as stand alone entities without dealing with a pulse motor setup where we know that either type of coil will export energy to the rotor.  As stand-alone entities there is no "magic fast energizing" for a series bifilar coil that has the same inductance as a regular coil.  I can't see them being different as a drive coil.

It's possible that you and Farmhand are leading yourselves down the wrong garden path.  It can happen to anybody.  So it's a good exercise to give these concepts a critical analysis.  Throwing a slogan at a technical point with no sound technical basis behind it is unwise.  Right now there is no sound technical basis to state that a series bifilar coil will energize faster and give you better performance for reasons already explained.

You are not making any sense.

No, I am making perfect sense.  The only ways to get current to flow through a coil faster is to increase the excitation voltage and/or decrease the inductance of the coil.  It has nothing to do with 1.5 volt pulse motors.

If the bifi were made to oscillate at say 1khz, the pulsing that coil with a 1ms pulse would be accepted into the coil very well as it is in the freq range.

Hard to say because there is not enough information.  If you are talking self-resonance here, that's one big mother of a coil.

Again, and I went over this in my post, you are ignoring facts about the bifi operation because you just cant get past the idea that the bifi is any different than a normal coil.  There really isnt much sense in me trying to describe it to you any further as its clear you are in denial and full rejection of what is being stated in the patent, or you are just not understanding it. I, or anyone can only go so far to break down your wall of disbelief.

The patent and your bench pulse motors have nothing to do with each other and it's a mistake to suggest that they do.  If you have "facts" about bifilar operation and can clearly demonstrate them then please do so.

MileHigh

[Farmhand]

Mags, this picaxe controlled boost converter looks fairly efficient. It can pass 50 to 60 Watts of power from 12 into 24 volts potential.

http://www.youtube.com/watch?v=eLnNgfaha10

I can provide the schematic and the code if anyone wants it, but the code has to be optimised for the coils.

Cheers

[MileHigh]

Farmhand:

P.S. Technically you are probably correct but, to the layman or the intuitive experimenter it doesn't matter that much as long as we understand what is going on. We do that by doing and observing. If the impedance is maximum then that is a lot different to infinite.

I have already stated that in electronics things are not always what they seem at first glance.  And I have stated that it's not easy to visualize the operation of a circuit or a pulse motor.  The bench is your reference, keeping in mind the "first glance" caveat.  And you can't forget that the more bench skills and experience and background knowledge you have, the better off you are on the bench.  But there are things that you can visualize too.

If there are Sacred Cows where it's interesting to kick the tires and have a second look, so much the better.  Using the "power comes up from the ground" as an example, avoiding months of experimenting with false conceptions in your mind would be a really good thing!  You yourself have already seen things like this before, as I suppose all of us have.  Just a few weeks ago we had, "the series bifilar coil makes a more powerful electromagnet" topic come up - it wasn't true.

How about this basic idea for the most efficient pulse drive coil setup and timing:  Lets assume a standard pulse motor configuration.  Let's say top-dead-center is zero degrees.  As the rotor magnet moves past TDC the angle increases.  Let's say the magnet feels the most torque from the drive coil at 8 degrees past TDC.

So if 8 degrees is the "sweet spot angle," why not energize the coil at say 4 degrees, and then cut the power at say 9 degrees.  Assume the coil has a snubber diode across it, so that it both discharges through the diode and gives a push on the rotor say between 9 and 12 degrees.

If you do your timing right at a given quiescent RPM and make sure the drive coil is pushing on the rotor both before and after the sweet spot angle for maximum torque, and you are recouping a good chunk of the remaining energy in the coil as part of the main rotor push, doesn't that seem sensible?

For completeness, there is overall geometry of the motor to think about also.  And very importantly, how much inductance do you use, how many turns?  Do you use a core or not, etc?  And even the excitation voltage comes into play, you can't ignore it.  There is a relationship between the excitation voltage and the inductance and the spinning rotor.  Certainly, you could say that your excitation voltage is fixed.  Then the amount of inductance in combination with the export of energy to the spinning rotor can be balanced relative to your excitation voltage.

I am always operating on the assumption that your goal is the maximum RPM for a fixed excitation voltage and a minimum power draw from the power supply or battery.

Cheers.

MileHigh

P.S.:  For extra completeness, I am going to split hairs even further because it's important.  Assume a fixed excitation voltage, and you have complete control over all of the other parameters.  Well, if you go purely for maximum RPM, it's safe to assume that you may have a high current draw and a high power draw.  So that isn't necessarily the most efficient motor configuration.   You could create the unit "RPM per input watt of power" and that would be very interesting because somewhere in the range of RPM, there is a "sweet RPM" that gives you the highest ratio of RPM per input watt of power.   What the actual power consumption is at that "sweet RPM" and what the "sweet RPM" is could be determined by measurements.   Just a thought.

Finally, I think that you are more interested in driving a generator and putting a useful real-world load on your pulse motor setups.  Needless to say, similar efficiency issues could be considered.