Language: 
To browser these website, it's necessary to store cookies on your computer.
The cookies contain no personal information, they are required for program control.
  the storage of cookies while browsing this website, on Login and Register.

GDPR and DSGVO law

Storing Cookies (See : http://ec.europa.eu/ipg/basics/legal/cookies/index_en.htm ) help us to bring you our services at overunity.com . If you use this website and our services you declare yourself okay with using cookies .More Infos here:
https://overunity.com/5553/privacy-policy/
If you do not agree with storing cookies, please LEAVE this website now. From the 25th of May 2018, every existing user has to accept the GDPR agreement at first login. If a user is unwilling to accept the GDPR, he should email us and request to erase his account. Many thanks for your understanding

User Menu

Google Search

Custom Search

Author Topic: Tesla's "COIL FOR ELECTRO-MAGNETS".  (Read 451677 times)

Offline wings

  • Hero Member
  • *****
  • Posts: 750
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #585 on: January 13, 2014, 06:09:42 PM »
Your right. Just applying dc, especially low voltage, if your not looking for it, you wont see it. ;)

45pf, you better be looking for very high freq initial spike at the time of applying the dc, not just looking at the DC magnetic field after the spike.

Oh well. Cheap tests. Cheap results. ::) Testing pancakes such as shown, the motor better be running somewhere below FM radio freq of rotation. Doing low freq or dc tests on a coil that is designed for radio freq doesnt make any sense to me.  ??? ::) And then to say the results are conclusive when it comes to the difference between bifi and normal coils is only half baked. ???

Just made a second bobbin to match a coil I have(normal 1 strand, 42awg, 5kohm, 1.6h 2 1/4 dia, 1/8 in thick) to make an equal bifi for comparison.  The normal coil lights an led with a slow pass of a mag.

Will be using a primary pulse coil of 2 turns on the outer diameter for testing.


Mags


gain 4 to 1:
http://alexfrolov.narod.ru/frolov_transformator.html

Offline conradelektro

  • Hero Member
  • *****
  • Posts: 1843
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #586 on: January 13, 2014, 07:34:28 PM »
I think Tesla found that the 'magic' of the bifilar pancake coil was it's ability as an antenna...

Do you mean, the bifilar coil is a better antenna than the monofilar coil?

When doing the "self resonance measurements" with an exciter coil ( see http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg382408/#msg382408 ) I saw that the exciter coil can be very far away from the pan cake coil (100 mm tp 150 mm). Is this an indication that a pan cake coil is a good antenna? What kind of experiment could one do in respect of "being a better antenna"? (Again comparing the monofilar and bifilar coil. Magic should be in the one and not in the other?)

Is this the claim: a bifilar pan cake coil is a better antenna than an equivalent monofilar coil?

The fact that the coil is both the inductor and capacitor in the tank means that the electrostatic component isn't hidden inside a capacitor shell - so the antenna is both electromagnetic and electrostatic. (Not sure if you're aware, but there are such things as capacitive/es antennas...)

When I do the "self resonance measurements" the bifilar coil is "inductor and capacitor" (no separate capacitor). The self capacitance which defines the self resonance frequency is the "hidden capacitor". But this is true for all coils? A coil is always an inductor and a capacitor (I mean its self capacitance).

Yes, the bifilar pan cake coil has a bigger "self capacitance" than an equivalent monofilar pan cake coil, but that is not magic, it might even be a flaw if you want higher frequencies. (A monofilar pan cake coil can be used at higher frequencies than an equivalent bifilar pan cake coil because it is not burdened with such a high "hidden capacitor".)

Yes, my bifilar pan cake coil can swing at 4 MHz without an external capacitor because it has a "hidden 45 pF internal capacitor". But my monofilar pan cake coil can swing at 9 MHz without an external capacitor because because it has a "hidden 9 pF internal capacitor". Where is the magic, only the "hidden capacitor" has a different value which causes the known consequences (like a certain self resonance frequency).

I am not criticising or ridiculing, I am asking "what is the magic"? The higher self capacitance is there, yes, but I see no consequences than the known ones. Every coil has a self capacitance, does the amount of self capacitance matter? Self capacitance matters in a known way (defines self resonance frequency), but does higher self capacitance bring in a principally new feature or effect?

Greetings, Conrad

Offline Farmhand

  • Hero Member
  • *****
  • Posts: 1583
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #587 on: January 13, 2014, 08:36:04 PM »
@Farmhand:

I showed that my bifilar pan cake coil has a lower self resonance frequency than my monofilar pan cake coil (bifilar ~ 4 MHz, monofilar ~ 9 MHz).

From this follows that the bifilar pan cake coil has a higher self capacitance than the monofilar pan cake coil (bifilar ~45 pF, monofilar ~ 9 pF).

The inductance of both my pan cake coils is ~34 µH.


What do you mean by "negating the self inductance of the coil by exciting it at or around it's self resonant frequency"? What is "self inductance"?

I excited both coils around their self resonance frequency and they behave like all coils. (The reactance increases which can be seen as a rise of the Voltage over the coil.)

What should happen in a bifilar pan cake coil when it is excited at its resonance frequency?

What should happen in a monofilar pan cake coil when it is excited at its resonance frequency?


Again, I am not criticising, just trying to understand so that I can measure an alleged effect.

Greetings, Conrad

P.S.: I am not off topic, I just measure systematically to separate the known from the unknown.

Same thing will happen with both except with the bifilar it will happen at a lower frequency. As you've shown.

Negating the self inductance means that the current will flow with nothing more than the DC resistance of the wire.

It's all explained in the patent. And it's pretty much all the patent is about.

I think a distinction needs to made between exciting a coil at or about it's resonant frequency, and exciting a coil to resonance.

Self inductance as seen by the supply. When we power factor correct an inductance we add a capacitance to stop the false currents or reactive power. Basically we tune the inductance/capacitance so its resonance under load is at about the applied frequency.

No magic, just a use. If you want a higher frequency you would not do it, same as you would not use a capacitor if it caused the frequency to be too low, that is also in the patent.

Saying it isn't so is calling Tesla a liar. And saying the patent examiner was wrong to grant the patent.

Quote
In electric apparatus or systems in which alternating currents are employed the self induction of the coils or conductors may, and, in fact, in many cases does operate disadvantageously by giving rise to false currents which often reduce what is known as the commercial efficiency of the apparatus' composing the system or operate detrimentally in other respects. The effects of self-induction, above referred to, are known to be neutralized by proportioning to a proper degree the capacity of the circuit with relation to the self induction and frequency of the currents. This has been accomplished heretofore by the use of condensers constructed and applied as separate instruments.

My present invention has for its object to avoid the employment of condensers which are expensive, cumbersome and difficult to maintain in perfect condition, and to so construct the coils themselves as to accomplish the same ultimate object.

I would here state that by the term coils I desire to include generally helices, solenoids, or, in fact, any conductor the different parts of which by the requirements of its application or use are brought into such relations with each other as to materially increase the self-induction.

l have found that in every coil there exists a certain relation between its self-induction and capacity that permits a current of given frequency and potential to pass through it with no other opposition than that of ohmic resistance, or, in other words, as though it possessed no self-induction. This is due to the mutual relations existing between the special character of the current and the self-induction and capacity of the coil, the latter quantity being just capable of neutralizing the self-induction for that frequency. It is wellknown that the higher the frequency or potential diierence of the current the smaller the capacity required to counteract the selfinduction; hence, in any coil, however small the capacity', it may be sufficient for the purpose stated if the proper conditions in other respects be secured. In the ordinary coils the difference of potential between adjacent turns ror spires is ,very small, so that while they are in a sense condensers, they possess but very small capacity and the relations between the two quantities, self-induction and capacity, are not such as under any ordinary conditions satisfy the requirements herein contemplated, because the capacity relatively to the self-induction is very small.

Cheers

Offline conradelektro

  • Hero Member
  • *****
  • Posts: 1843
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #588 on: January 13, 2014, 09:49:34 PM »
@Farmhand: thank you for taking the time to explain. I think you read the patent correctly, it says just that. But one has to read attentively and with some background knowledge to get it.

Just to check that I understood correctly I make up a hypothetical example.

Let's take my two pan cake coils (the monofilar has a self capacitance of 9 pF and the bifilar has a self capacitance of 45 pF):

- the supplied or applied frequency is 4 MHz (I just make that up to have an example)

- in order to "power factor" correctly we have two possibilities:

A) we take the monofilar pan cake coil and add a 36 pF capacitor (9 + 36 = 45 pF) so that it resonates at 4 MHz

B) we take the bifilar pan cake coil which is in resonance with 4 Megahertz without adding any capacitor because its self capacitance happens to be 45 pF

- Alternative B) is cheaper because we do not need to buy a capacitor.

- if the supplied or applied frequency were 2 MHz we would need a capacitor for both of my pan cake coils in order to "power factor" correctly (from my many experiments with my pan cake coils I happen to know that we need a 100 pF cap for the monofilar and a 74 pF cap for the bifilar pan cake coil to make them resonate at 2 MHz)

Greetings, Conrad

Offline tim123

  • Hero Member
  • *****
  • Posts: 509
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #589 on: January 13, 2014, 10:48:10 PM »
Is this the claim: a bifilar pan cake coil is a better antenna than an equivalent monofilar coil?

No claim as such, just a thought... If it's acting as a capacitive antenna - then the increased capacitance would probably help by making a bigger electrostatic field.

I think it's interesting that he did use this coil config for power transmitting & communications experiments too. He obviously developed it for the application described, and then found it useful for other things...

Offline conradelektro

  • Hero Member
  • *****
  • Posts: 1843
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #590 on: January 14, 2014, 12:15:10 AM »
I made a new exciter coil with 4 turns (see the attached photo) which is now in the right orientation in respect to the pan cake coil. Because it is fixed to a central plastic bolt of the pan cake coils it can be mounted at exactly the same position at both pan cake coils.

Measurements gave about the same results as in this video http://www.youtube.com/watch?v=spQ9yLdb7v4&feature=youtu.be

In addition I tried the "Inductor Capacitance and Inductance Estimation with the two frequencies method" according to this web site http://www.qsl.net/in3otd/inductors.html (with the new exciter coil and two different tank capacitors).

This method needs two measurements with two different tank capacitors (see the attached drawing). The estimate for the inductance is pretty good, also for the self capacitance of the bifilar coil. The self capacitance of the monofilar is estimated a bit low (2 pF instead of 7 pF to 9 pF).

The 1 pF decoupling capacitor (for the scope probe) is very important, the "two frequencies method or estimation" gives very bad results without it. All measurement methods need the 1 pF decoupling cap to work well. The involved frequencies are high enough (about 1 MHz to 9 MHz) to be disturbed by the scope probes input capacitance of about 100 pF.

This concludes the measurement of

- induction ~34 µH for both pan cake coils (with a LCR-meter and the "two frequencies estimate")

- self resonance (bifilar coil ~4 MHz, monofilar ~ 9 MHz) and the resulting self capacitance (bifilar ~45 pF, monofilar ~7 pF) with two methods:

      * the classical method (resistor in series with the pan cake coil see video http://www.youtube.com/watch?v=fC84W0PIZoE
      * the exciter coil method (see video http://www.youtube.com/watch?v=spQ9yLdb7v4&feature=youtu.be and attached drawing and photo)

Together with the spin tests (pick up coil quality) and the magnetic field measurement (video http://www.youtube.com/watch?v=gCEqnX1JsGw) we now have already some tangible facts about pan cake coils (bifilar and monofilar).

The magic difference is still elusive. What is the magic difference or the magic effect (in understandable terms, I know about the Voltage between neighbouring wires and the difference in self capacitance)? How can the magic be measured (without exotic equipment)?


I will work a bit on my 12 V motor spinner (new coupling between motor and axis carrying the ring magnet, should then do 10.000 rpm) and will prepare forms for helical coils (one bifilar the other monofilar, otherwise identical).

Does it make sense to start with "one layer helical coils" or should I go directly to helical coils with many layers of windings? The core will be 10 mm and can then be in a changeable way an air core, a Ferrite core and a soft iron core (bundle of iron wire sticks).

Greetings, Conrad

Offline Magluvin

  • Hero Member
  • *****
  • Posts: 5886
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #591 on: January 14, 2014, 12:36:37 AM »
@Mags:

What do you mean by "very high freq initial spike". Please look at the drawing, I think you meant a "pulse of short duration"? Do you mean that one should send a short pulse through the pan cake coil? If you mean that, what should be the "astonishing effect"?

Again, I am not criticising, just trying to understand and later on trying to reproduce the alleged effect.

Greetings, Conrad

P.S.: A measurement can not be cheap, it can only be correct or incorrect. Why the insults? I am not attacking, I am measuring and then I am being attacked.


"What do you mean by "very high freq initial spike"

With the capacitance of the coil, the initial current is high, even with DC input. The coils capacitance takes on initial current regardless of inductance, and only lasts for 1 half of the resonant cycle. So at 4mhz, the scope would have to be set up to see it. ;) If the source is a batt, then a cap across the batt should show a bit higher spike than batt alone, giving a more immediate input as batts cant discharge as much immediate current as a cap.

Say if we have a cap and coil in series and apply dc, the inductance of the coil will impede charging the cap. ;) So having the capacitance in the coil is a bit special. ;D


"P.S.: A measurement can not be cheap, it can only be correct or incorrect. Why the insults? I am not attacking, I am measuring and then I am being attacked."

The measurement advice you followed was concocted to show nothing special.  ;) Especially with coils that would be impossible to get into resonance using a pulse motor and way out of range for seeing anything with DC testing without really looking. The tests were what they were. You were just 'following' instructions that were not from the person who gave you the coil designs to test.  ;) And you found nothing special. ;)

There is no 'magic'. It all can be defined.  The bifi gives us options that are not exactly the same as separate components.

Mags

Offline conradelektro

  • Hero Member
  • *****
  • Posts: 1843
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #592 on: January 14, 2014, 12:54:25 AM »
With the capacitance of the coil, the initial current is high, even with DC input. The coils capacitance takes on initial current regardless of inductance, and only lasts for 1 half of the resonant cycle.

................ So at 4mhz, the scope would have to be set up to see it. ..................

 If the source is a batt, then a cap across the batt should show a bit higher spike than batt alone, giving a more immediate input as batts cant discharge as much immediate current as a cap.

Say if we have a cap and coil in series and apply dc, the inductance of the coil will impede charging the cap. ;) So having the capacitance in the coil is a bit special. ;D

What exactly should be seen by the scope and how should it be set? (I am talking about the difference between my monofilar and bifilar pan cake coils. The "synchro coil" is no longer on my agenda and not part of this thread, it needs a different type of person than me.  You could do a "synchro coil", you seem to believe in it.)

The measurement advice you followed was concocted to show nothing special.  ;) Especially with coils that would be impossible to get into resonance using a pulse motor and way out of range for seeing anything with DC testing without really looking. The tests were what they were. You were just 'following' instructions that were not from the person who gave you the coil designs to test.  ;) And you found nothing special. ;)

So, give measurement instructions! What should be measured and how? (I am talking about the difference between my monofilar and bifilar pan cake coils.)

What wrong instructions have been given in connection with my monofilar and bifilar pan cake coils and their measurement?

Greetings, Conrad

Offline Magluvin

  • Hero Member
  • *****
  • Posts: 5886
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #593 on: January 14, 2014, 12:56:10 AM »
Was putting some thoughts together today.

Below, once more, Im posting the pdf that explains how flux propagates through a closed transformer core(toroid). Helps to understand the second pdf.

The next pdf shows how to add a second magnetic circuit with the secondary that when you load the secondary, the input currents actually go down. No magic here. And no extra power out as the pdf states. But, what the pdf does claim is that loading the secondary wont kill off the 'resonance' of the primary. ??? ;D

I have tested the dual core and yes it does decrease the input of the primary when the sec is loaded due to 'increasing' inductance of the primary instead of the standard which decreases primary inductance when the sec is loaded, but output power is no more than the input.   I still have to test a bifi primary here to see if resonance of the primary is not killed off by a loaded sec.

In my experience, when we apply an input to a resonant circuit, we see higher voltages than the input itself at resonance. But direct loading kills of the resonance.

But here with the dual core setup in the second pdf, we may be able to take advantage of that resonant rise without killing it off with loading of the sec. ;)

Mags

Offline Magluvin

  • Hero Member
  • *****
  • Posts: 5886
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #594 on: January 14, 2014, 01:53:10 AM »
What exactly should be seen by the scope and how should it be set? (I am talking about the difference between my monofilar and bifilar pan cake coils. The "synchro coil" is no longer on my agenda and not part of this thread, it needs a different type of person than me.  You could do a "synchro coil", you seem to believe in it.)

So, give measurement instructions! What should be measured and how? (I am talking about the difference between my monofilar and bifilar pan cake coils.)

What wrong instructions have been given in connection with my monofilar and bifilar pan cake coils and their measurement?

Greetings, Conrad


"What exactly should be seen by the scope and how should it be set? (I am talking about the difference between my monofilar and bifilar pan cake coils."

With a straight DC application to the coil, the scope would have to trigger and show the initial current flow. This would be a 1 shot scope shot. Cuz after that, its just a DC trace.

Me personally, I have no use for coils that work in the radio range. Not that someone might be able to use them for something, but I tend to like below 100khz. And if we are interested in using bifi in a motor, the coil needs lots of turns. Im surprised you were able to measure actual capacitance of the normal coil. My 'meters' tend to show quite high capacitance of a regular coil, of which is not accurate. The only way I know of is to calculate using freq of resonance and inductance to get accurate capacitance. Maybe some meters can measure it. Of the 3 I have, I cannot.

The more turns of a regular coil, the more the capacitance between the 2 leads of the coil is just a bunch of series capacitances between turns. In a bifi coil, the more turns is directly related to an increase in parallel capacitance between the bifi turns. 

So the differences between your coils(in the uh and pf) seem like nothing special. But the more turns, the more of a difference you should see.

Say we have a 2 turn coil. It can be considered a normal coil. But it is also the exact definition of Teslas bifi. Example, if we apply 10v across the 2 turn coil, at any point on the 2 turn coil we can measure 5v difference from 1 turn to the next. 1/2 the input.

So now say we have a 10 turn coil, normal and bifi coils.  The normal coil, 10 turns, with 10v across the coil, we can measure any adjacent turns and we will see 1v, but the bifi will see 5v.

100 turns, normal coil .1v between adjacent turns, bifi still 5v between adjacent turns.

So the more turns, the more the difference.  1000 turns, .01v between adjacent turns, bifi 1000 turns, still 5v between adjacent turns.  That 5v between turns(capacitive) is a heck of a lot more energy than .01v between the yet smaller capacitance of the normal coil.

So, though they are very nice coils you have made, they will show minimal differences compared to many turn coils. In the pat, I and some others believe the illustration of pancakes was to easily describe that actual wiring differences. Simple to see. And the pat states that the bifi can be configured to any style of coil.



"So, give measurement instructions! What should be measured and how? (I am talking about the difference between my monofilar and bifilar pan cake coils.)"

Explained above. What we are interested in is working the coils at resonance. Not below, nor above freq of resonance.


"The "synchro coil" is no longer on my agenda and not part of this thread, it needs a different type of person than me.  You could do a "synchro coil", you seem to believe in it.)"

I dont believe in the Syncro coil 'yet'. Have I stated that somewhere? I have not tried it. But if I did, I would make sure I replicated it to spec to try to get the most accurate comparable results as possible. Any difference could throw things way off and may not work at all. I would like to see more before I delve into it. I asked you earlier about Syncros accusation that you didnt test the Synchrocoil properly, but no response. He claims you didnt use the diode. I can see why you got nothing into the cap. Did you use the cap or just a resistor load? If it is very high freq ac, even very low voltage, the cap alone would need to be very tiny and equipment to have the ability to read such AC ghz on the cap. With the diode, the coil would charge the cap with dc, which would make it easier to 'see' what is in the cap without special equipment. From what I understand.


Mags



Offline Magluvin

  • Hero Member
  • *****
  • Posts: 5886
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #595 on: January 14, 2014, 02:28:03 AM »


The magic difference is still elusive. What is the magic difference or the magic effect (in understandable terms, I know about the Voltage between neighbouring wires and the difference in self capacitance)? How can the magic be measured (without exotic equipment)?




Who in this thread is claiming 'magic'? I didnt post the word magic. Did synchro state the word 'magic'?

Hmm, who else here used the word 'magic' in this thread? hmmm

Mags

Offline synchro1

  • Hero Member
  • *****
  • Posts: 4652
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #596 on: January 14, 2014, 03:12:08 AM »
@Magluvin,


                Here's the "Synchro Coil" Conradelektro tested, modified by Milehigh. They wonder why I'm furious with them!

Offline Magluvin

  • Hero Member
  • *****
  • Posts: 5886
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #597 on: January 14, 2014, 03:18:54 AM »
@Magluvin,


                Here's the "Synchro Coil" Conradelektro tested, modified by Milehigh. They wonder why I'm furious with them!

Hey Sync

Where is the diode and cap?  You have 2 resistors in parallel across the coil. Or is that the way they tested it?

Mags

Offline MileHigh

  • Hero Member
  • *****
  • Posts: 7600
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #598 on: January 14, 2014, 04:18:24 AM »
Conrad:

Note that the patent was written in the 19th century.  It's possible that the word "electromagnet" was used in the title of the patent just so people, the patent examiners, could relate to it and have some frame of reference.  Think if in 1975 you wanted to patent the concept of the "smartphone."  People would not understand, the cell phone network did not exist and nobody imagined that you could have a computer in you pocket with a "Jetson's" display.  (A children's cartoon about a family living in the distant future where everything is automated and there are domestic robots and flying cars.)  So chances are your patent application in 1975 for a "smartphone" would be rejected because the patent examiners would have no frame of reference.  If you called it a "miniature walkie talkie with a miniature cathode ray TV tube" your patent might be granted.

People in the 19th century understood that there were "electromagnets" in telegraph machines and phone bell ringers but that's about it.  They had no concept or understanding of the term "inductance" and therefore had no frame of reference.   That's my theory.

The Tesla patent is akin to the patent for the transistor.  It's a piece of technology that all alone does not do much.  We know that you can do countless applications with transistors working in tandem with other components.  The question is can something analogous be said about the Tesla bifilar coil?  That's a key question.

With respect to the patent.  It says when the coil is excited at the resonance frequency, the self-inductance (i.e.; inductance) goes away and it simply will conduct the AC like the coil has "disappeared" and the only impedance that you see is the pure wire resistance.

If you look up "parallel LC circuit" and "series LC circuit" you will see that the parallel LC circuit has infinite impedance at the resonance frequency and the series LC circuit has zero impedance at the resonance frequency.

What that means is the assumption that we have been working with is that the capacitance inherent in the series bifilar coil is acting like a parallel LC circuit.  That's what your test shows when you see the maximum voltage across the coil in series with a resistor.

The interesting thing is that Tesla's patent models the coil as a series LC circuit.  i.e.; when you make the measurement of the voltage across the coil in series with a resistor you should measure zero.

So it's interesting that apparently nobody (that I am aware of around here) has been able to actually confirm what the patent says by testing an inductor.  That doesn't mean it can't be done.  I think that it's fair to say that discovering a frequency where the inductor acts like a series LC circuit is possible, but elusive and difficult.

So possibly right now on this forum nobody has successfully replicated the patent!  People have replicated and observed parallel LC resonant behaviour in their series bifilar coils but they haven't replicated and observed series LC resonant behaviour in their series bifilar coils.

MileHigh
« Last Edit: January 14, 2014, 06:33:05 AM by MileHigh »

Offline MileHigh

  • Hero Member
  • *****
  • Posts: 7600
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #599 on: January 14, 2014, 05:07:48 AM »
Conrad:

I just watched your clip.  So the strength of the magnetic field generated by both types of coils is the same.

Now we all recall Synchro1 stating that the electromagnet test where he picks up paperclips would show that the bifilar coil would outperform the regular coil.  There were a lot of big boasts and grandiose claims. That test was also a DC test.  The test you did in your clip was essentially the same test.

The idea of starting with learning and verifying basic concepts and then building up from there is a fundamental technique for learning, and it applies to electronics also.

Congratulations on a great test.  This was a test with fine granularity in measuring the strength of the magnetic field.  That's in contrast to the paperclip test that was very rough in granularity, too rough to generate any serious data.

MileHigh

P.S.:  It looks like you have a real bench power supply.  You have two knobs, one for current and one for voltage.  That means that the power supply can act as a voltage source, or also as a current source.

To configure the power supply as a current source, turn the current knob all the way counter-clockwise to zero.  Connect the coil to the power supply, and also put a multimeter in series set to display current measurement.  You do not need a series resistor.  Then turn the voltage knob all the way clockwise to the maximum.

Then slowly turn up the current knob and observe how you can control the amount of current that flows through the coil.  It's as simple as that.  Careful if you open the circuit the power supply in current mode the voltage will jump to the maximum.  Note that means in theory to turn a current source power supply "off" you put a short circuit across the terminals.