A Coil, the Current and the Voltage

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  • Last Post 10 December 2020
Chris posted this 30 July 2017

At any one point in time, given the Magnetic Field B, we have two states that are possible in a Coil of Insulated Wire. These States are different when a Coil is being Driven, or Induced. What do I mean?

The Two States:

  1. Driving a Current into a Coil, by applying a Voltage across the Coil.
  2. An E.M.F (Electromotive Force) that is induced in a Coil.

State One, where we apply a Voltage across a Coil, we are driving the Coil and as a result, the Current will be in one direction, and the Voltage polarity in the other. If the Voltage across a Diode is Negative, no Current can flow. The Diode is said to be Off or Reverse Biased.

Figure One: The Capacitor does not charge, there is no path for the Current.


When the Mosfet is on, we have applied 10 Volts across the Coil:

Figure Two: Voltage applied across the Coil.



State Two, where an E.M.F is induced in the Coil, invoking Electromagnetic Induction, a discovery of Michael Faraday, some 186 years ago. Here we have Voltage and Current in the same direction.The Mosfet (Q1) is switched off, breaking the Voltage Applied across the Coil, the Coil’s Voltage Polarity reverses, and the Diode Conducts. With a positive Voltage across the Diode, it becomes Forward Biased and is now On.

Figure Three: We have Charge across the Capacitor.


When the Mosfet is switched off, the Magnetic Field B collapses and the Coil’s Voltage Polarity reverses, but the Current flow remains in the same direction.

Figure Four: The Induced E.M.F = -N dPhi/dt


Where the 100 Volts is the E.M.F Induced by Faradays Law of Induction. This is the Magnetic Field Collapsing, changing over time in proximity of the turns N.

And so, we can see now, how a Coil of Insulated Wire, has Two States!

It’s worth noting, Current flows have been mixed up over the years by Science. It’s not hard to see why; it is confusing to say the least. Let’s look at another example:


Figure Five: The Symbol for a Diode.


Figure Six: Diode Conducts and Capacitor Charges.


Figure Seven: Diode does not conduct and the Capacitor does not Charge.


Figure Eight: What is Current?


So what is the Current, what is it a flow of? The very word “Current” is defined as a movement of something! Yes, isn’t it confusing!


Figure Nine: Flow of Charges.


We have learned, in the Mr Preva Experiment, that we can Increase the Total Current in a Localised Circuit and thanks to the wise words of Floyd Sweet we know what this means:

In the specific case of positive charges moving to the right and negative charges to the left, the effect of both actions is positive charge moving to the right.

Current to the right is: I = da+ / dt + da- / dt.

Negative electrons flowing to the left contribute to the current flowing to the right.


Most likely the Positive Charges moving to the Right are Ions. But to be honest, who really knows.

So the Coil Changes, depending on what’s going on. What the Coil is being used for. It is an Active Element, acting like a Battery, when an E.M.F is Induced. Or if a Voltage is applied across it, it is a Passive Component, exhibiting the above mentioned change in Voltage Polarity after the applied Voltage is switched off.

I hope this helps some! Please point out any mistakes also, we want to get this as accurate as possible for others following.


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Chris posted this 30 July 2017

Hi Vasile, Sorry, I used what I thought we would all be very familiar with. Was only as an example.

The Important thing I was trying to cover, was that Coils Polarity and Current Flow.

I have seen what I believe to be much confusion surrounding Coils, Diodes, Voltage and Current, polarity's and directions, even by some advanced people over the years.

One example: Fet Diode Test

A test, I have seen this many times here on this forum!!!

What LED's will Light:

   D1: ?
   D2: ?
   D3: ?


Use the Right Hand Grip Rule to find the Polarity of the Magnetic Field, this is easy, but if one is not sure on the Current Direction, then this is not so easy!


Hope this clear up any possible confusion...



Chris posted this 20 October 2020

My Friends,

An article I feel is important for us. FACT: Electron moving, is Current!

Tiny device pumps out one electron at a time

02 Dec 2016  

One at a time: the single-electron pump. (Courtesy: PTB)

Physicists should finally be able to rid themselves of the cumbersome and inaccurate definition of the ampere. That is the claim of metrologists in Germany, who have measured electrical current by counting single electrons travelling along a microscopic wire. The researchers say that their technique will allow scientists in a number of different disciplines to make better measurements of tiny currents.

The move to revamp the ampere is part of a more general overhaul of the SI system of units. It is envisaged that all seven base units – the ampere, second, metre, kilogram, kelvin, mole and candela – will be anchored to unvarying constants of nature. In particular, scientists are eager to redefine the kilogram, which is currently based on the mass of a specific lump of platinum-iridium sitting in a Paris safe and slowly shedding atoms.

It is partly to sever its link with the kilogram that metrologists are keen to redefine the unit of electrical current. At the moment, one ampere is defined as the current flowing in two narrow, infinitely long parallel conductors placed one metre apart in a vacuum that generate between them a force of 2 ×10–7 N for every metre of length. This formulation is a problem because it means that the ampere is defined in terms of the kilogram (as well as the metre and the second) because force is equal to mass times acceleration. Also, nothing can be infinitely long, so this requirement must be approximated somehow.

Transistor-like device

This latest work was carried out by Frank Hohls and colleagues at the German National Metrology Institute (PTB) in Braunschweig and aims to define the ampere in terms of a certain (large) number of single electrons passing through a conducting channel in unit time. Central to the proposal is the construction of a “single-electron pump”, a transistor-like device that transmits just one electron when activated by a gate voltage. With the voltage oscillating perhaps several billion times a second, the device would generate a current that is large enough to calibrate an ammeter – thus revealing how accurate the instrument is.

The team made single-electron pumps from quantum dots – sub-micron sized conducting areas etched on to semiconductor substrates. Operating the pumps at millikelvin temperatures, they apply a roughly 0.5 GHz gate voltage and a second, fixed voltage across each dot to set up a time-varying potential well that briefly captures and then ejects single electrons. To establish the accuracy of their devices, the researchers use a specially developed amplifier that converts the current flowing through it into a voltage, which is measured by a voltmeter calibrated using two other quantum phenomena – the quantum Hall effect and the Josephson effect.

The researchers were able to measure the current transmitted by the pumps with an accuracy of 0.16 parts per million. This is fractionally better than they achieved with an earlier version of their device last year, which matched the accuracy of measurements that can be carried out using the existing force-based definition of the ampere – 0.2 parts per million. The new measurements were also done more quickly – requiring just 21 hours, rather than the several days employed a year ago. “The measurement set-up used in this experiment represents the state-of-the-art in small-current metrology,” says group member Hansjörg Scherer.

Aerosol counting

According to Scherer, who led the PTB effort to design the new amplifier, more accurate measurements made possible by the pumps could prove useful in a number of areas. Among them, he says, are the determination of radioactivity levels in ionization chambers and counting aerosol particles in the air.

Ian Mills, a metrology expert at the University of Reading in the UK, praises the “valuable and excellent work” being done on electron counting at the PTB. But he believes that a better definition of the ampere can be obtained simply by using the most accurate value for the electron charge available today – which is based on other measurements including that of the fine structure constant. That value of the ampere has an accuracy of about 20 parts in a billion and is, he says, most likely to be used in the new definition of the ampere that should be approved by the General Conference on Weights and Measures – the body that will authorize changes to the SI system. “I think the electron-counting experiments are fascinating,” he says, “but they are not yet sufficiently precise to compete.”

François Piquemal of the National Metrology and Testing Laboratory (LNE) in Paris, takes a slightly different view, arguing that electron counting offers a way of realizing the ampere in practice, rather than defining it. He maintains that single-electron pumps are best suited to measuring currents up to about a nanoamp, while an alternative approach – involving the combination of quantum Hall and Josephson standards through Ohm’s law – is best for larger currents. “In my opinion, these two methods are complementary for the future mise en pratique of the ampere,” he says.

Ref: Tiny device pumps out one electron at a time - physicsworld.com


Take special note of the Right Angle of the device, this is The Lorentz Force.

This article uses a slew of very important words: Acceleration, Electrons, Travelling, Time-Varying Potential and more.

Best wishes, stay safe and well My Friends,


Forushani posted this 21 November 2020

what is the appropriate Diode to use on the coils?

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  • Chris
Chris posted this 21 November 2020

Hi Forushani,

Don't forget: Keep it simple.

Any diode that's within the ratings. Ratings of Voltage and Current within what you want to use it for. Later, when you have more specific uses, this can get a little more complicated. But, for now, Simplicity is Key.

Best Wishes,



P.S: See the Diode's Datasheet for the Ratings.


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  • Jagau
Greywolf47 posted this 30 November 2020

I am currently building Figuera's infinate energy machine. I have replaced ALL of the part G and the resistors with a Hammond 1182 L30 toroidal transformer with a center tap. I am running it with a 12 volt 750 watt output inverter powered from a 12 volt auto battery giving 120 volts AC output. I am using diodes to change the 30 volt ac output to dc at about 14 volts. This is quivalent to using the part G and resistors to get 2 positive sign waves 180 degrees inverted as the part G would produce going through the resistors bank. I have seven sets of 3 soft iron laminated cores. The 3 iron cores connect to each other with finger joints after they are wound with a bifilar wound 16 guage primary. Each of the primary windings is powered by the toroid 180 degrees inverted so that the 60 hz frequency changes the iron core from N to S and S to N 120 times per second. There are 46 turns of each wire side by side with a total of 92 turns. Over the primary coil there are 2 partnered output coils as Chris has shown in his diagrams and video discussions. They each are wound with 500 turns of 22 guage magnet wire. I should have this unit ready for testing by Dec 10 and will try to post results then.

Chris posted this 30 November 2020

Hi Greywolf47, Welcome!

Thanks for Sharing! Sounds very cool!

At the base level, every time a Current flows in a wire we have an Action. Every time when we have an Action, we have a Reaction.

  • The Action is the Changing Primary Current in a Transformer.
  • The Reaction is the Secondary Coil in a transformer having an Induced E.M.F


Well, truth is, this simple set of: { Action, Reaction } pair, we have been using of many decades. We all know how this works! We commonly see this in many places:


What most people have missed, is this Action, Reaction Pair is incomplete! It for fills Symmetry, but not Asymmetry!

What we want is, a set of: { Action, Reaction, Counter-Reaction } triplet.

This for fills Asymmetry and Symmetry! A Complete System, the Part Most People have been missing for many decades! 

It sounds like you are on the right track, if you apply this thinking, you will succeed! Every Coil has a Polarity and this is super Important!

Well Done and Thank You for Sharing!

Best Wishes,


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  • cd_sharp
Lighting posted this 02 December 2020

I wanted to ask if everyone is familiar with the work of this person?
He quite competently approached the issue of the implementation of devices, but in my opinion some trifles (perhaps not trifles) were still overlooked, as in fact, for most people who dealt with the manufacture of a Tesla transformer.
For example: Tesla used Leyden jars made from glass bottles, salt water, with a COPPER central core (electrode) inserted into the cork and an outer lining of ALUMINUM foil. By analogy with modern batteries, it can be assumed that the capacitor that was obtained in this way is polar, since Cu - copper (according to the periodic system of chemical elements) is positive, and Al - aluminum - is negative (I think this is not without reason). Perhaps the design of such a Leyden jar implies a certain potential difference between the electrode and the plate, since their area is extremely different. Speaking of area, when Tesla made calculations in formulas, he used measurements of coils and capacitors in centimeters.

I apologize in advance for my English, I use a translator.
Respectfully all, I hope this will help or lead to any thoughts.

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  • cd_sharp
Chris posted this 02 December 2020

Hello and welcome Lightning!

I have not heard of this person. I will look at it further tomorrow. Alex Org's videos do look interesting, however, something more of us here have already experimented with.

We have many successful experiments here, a read of the forum of very worth while. Sorry, I only have the forum in English at the moment.

Please feel free to ask questions if you need help here!

Welcome and enjoy!

Best Wishes,


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  • cd_sharp
Lighting posted this 02 December 2020

Unfortunately, I still cannot boast of my results due to the fact that I started relatively recently, with the complete absence of all measuring equipment except for the tester, and the absence of some components to complete my Tesla transformer. As soon as I can continue, I will definitely share my observations and developments. My desire to understand processes transcends any difficulty. If a person 100 years ago could do it without modern equipment, I think, studying his works, understanding will come to us.
During the time that I have been doing this, I realized that in many forums in my region there is a lot of deliberately false and confusing information, a lot of trolls, apparently this was done on purpose.
If you are interested, then I can throw off links to videos that have interesting effects that might help someone, these videos are in Russian, but what you see will not require detailed comments, but if someone needs text or key points I can help with translation.
Do not worry that the forum is only in English, I successfully use a translator, some points are not immediately understood due to the "high-quality" translation, but I manage, I have been reading your forum for almost a week, a lot of interesting things, thank you.

Munny posted this 02 December 2020

This experiment has left me bewildered for years:

If anyone can explain how and why those windings around the outside of the toroid core change the behavior, I would be most thankful.

Vidura posted this 03 December 2020

Very interesting, Thanks for sharing. It is an effect which has not yet been explained by science. I can only point towards a hypothetical idea. The magnetic domains of the core are normally random or moving back and forth at the best case. The perpendicular winding provide a second phase with a temporal shift, and causes the domains to rotate completely and coherent. Similar the AC inductance motor with shunt winding (by Tesla). The effect is enhanced by the HV pulses from the TC. Effect still under investigation.

Lighting posted this 09 December 2020

I need help. I read many different forum threads, a lot of information, and realized that I was completely confused. What I was working on now appears in a completely different form. I realized that I needed to start all over again. The Tesla transformer I am working on, there are only a few parts left to assemble, this is the signal generator, the oscillating primary coil and the Leyden jars. The main problem is a generator, I do not fully understand which option will be correct, (is it needed at all?) Or it will be a generator based on a transistor key, or it will be a motor with a rotating disk on which there will be contacts to close the primary coil. I plan to use: 220 volts at the input, a 6 ampere breaker, then a 220> 15 volt step-down transformer, then a TV step-up transformer (TDKS) about 10 -12 kV at the output, spark gap on tungsten rods parallel to the primary coil, in series connected capacitors at one end and the other end of the primary coil, the primary coil and the secondary high-voltage coil with a large number of turns.
I would be very grateful if you could advise me a working oscillator circuit based on transistors of different output signal types.

Jagau posted this 09 December 2020

Hi lighting

There are hundreds of web pages that talk about the manufacture of the Tesla coil.
One of the excellent and solid designs of the oscillator and output circuit is that of Richard Burnett, an engineer in power electronics


The oscillator



The ouput

if it can help

Chris posted this 09 December 2020

Hello and Welcome Lightning!

Please feel free to create your own thread: "Lightning's Tesla Coil Build" and we can help.

Some members here very advanced! Having not only top level Electrical Engineering Skills, but Machines running and so on. We all learn from each other and all here are happy to help! We are one big happy family here!

Jagau is very advanced and has given excellent advice! Thank You Jagau!

Best Wishes and Welcome!


Lighting posted this 10 December 2020

Hello everybody!
Thank you for the proposed circuits, but I'm not that strong in electronics, I can solder well, but I don't know much about understanding the circuits. I'm trying to build a simple 555 timer and NPN transistor.
Thank you for the suggestion to create a Tesla branch, but I think I don't have much information and developments that I could offer.

It is important for me now whether I understand the Tesla process correctly?
I hit the coil with an impulse, such that I allow the solitary capacitance in the coil to be charged, the impulse should be so short in time that it can reach the edge of the coil and instantly cut off, then the charged capacitance of the coil returns the wave to the ground, while I get free vibrations, in the moment when the pulse begins to reflect from the ground, I give the next pulse, thereby pushing the pulse from free oscillations that moves to the edge of the coil. In this case, the coil must have a small inductive resistance so that the wave does not quickly fade away (non-inductive coil), I suppose that a non-inductive coil can be obtained with a certain pitch between the turns, the distance between the turns must be at least one radius of the wire thickness (due to the skin effect, depends on vibration frequency). Since I initially apply a high voltage to the inductor, I do not need inductance in the secondary coil to increase the voltage, therefore I can make it non-inductive.

Jagau posted this 10 December 2020

Hi lghting

You have in this site all the questions and answers, it is a very well done Tesla coil site, design. construction and operation.



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Weeks High Earners:
The great Nikola Tesla:

Ere many generations pass, our machinery will be driven by a power obtainable at any point of the universe. This idea is not novel. Men have been led to it long ago go by instinct or reason. It has been expressed in many ways, and in many places, in the history of old and new. We find it in the delightful myth of Antheus, who drives power from the earth; we find it among the subtle speculations of one of your splendid mathematicians, and in many hints and statements of thinkers of the present time. Throughout space there is energy. Is this energy static or kinetic? If static, our hopes are in vain; if kinetic - and this we know it is for certain - then it is a mere question of time when men will succeed in attaching their machinery to the very wheelwork of nature.

Experiments With Alternate Currents Of High Potential And High Frequency (February 1892).