Maxwell's equations actually require some advanced math. To keep things simple, I just say: 1. Putting a voltage across (or a current through) a wire creates an electric field. 2. The changing electric field creates a magnetic field. In a toroid, this field is ring shaped, inside the toroid itself. When you wrap ANOTHER coil on the toroid, the same magnetic field is inside. This leads to: 3. A changing magnetic field creates an electric field, which can be picked up by a wire. Which is what you said, I'm just summarising here.
You probably have chokes with two identical windings in mind. If it is inserted into a two wire line, the wanted current flows through both windings in an opposite direction. The magnetic fields cancel each other, so the inductance for the wanted current is zero. Unwanted common mode current, on the other hand, encounters high inductance, which limits its intensity. Another case - toroids beaded on a coxial cable. A coaxial cable behaves as three conductors at RF: the inner one, the inner surface of the braid and the outer surface of the braid. Ferrite toroids or tubes beaded on a coax increase the inductance of the outer surface, where unwanted, unbalanced and RFI currents flow. The inductance of the two other conuctors is not affected.
4:15 Two types of material for toroids (and other shapes of RF cores) are used: A/ ferrite - a sort of magnet permeable ceramic, which is sintered at high temperature and treated in a special manner. It is not powdered nor glued. If such core is heated above certain temperature (e.g. by excessive RF power losses), it loses its magnetic properties forever. B/ carbonyl - powdered iron mixed with glue and hardened. If it is overheated and cooled again, its magnetic properties return back.
It is not necessary for a toroid to be made of a magnetizable material to be useful for confining the magnetic field. A solenoid (or long thin coil of wire) has its magnetic field mostly confined to the inside of the solenoid. Magnetic field lines are always closed, and so in a linear solenoid even without any magnetic medium inside it, the lines loop back around the outside of the solenoid to the other side. If the solenoid is bent into a circle so that the end of the solenoid meets the front, the magnetic field lines in the loop directly back to the other side crossing the minimum distance because the ends of the solenoid nearly meet. In fact, at high frequencies, a solenoidal form made using a ceramic toroid is sometimes used that is non-magnetic. In an ordinary inductor, a magnetic field must be established in the magnetically permeable medium inside the toroid (whether or not it is air or iron powder, ferrite, etc.) in order for a current to flow in the wire. The current rises in time in proportion to the voltage and inversely proportional to the inductance. As the current rises, energy builds up in the magnetic field in the core. Now say we take two wires and twist them together and thread them together around the core. Let's say we apply current to only of the wire, and leave the other wire open circuit. This is the same as only having one wire, and again it takes energy to build up the magnetic field in the core and for the current to flow. But let's say we now short the other wire. Now when apply a current to the other wire, a current can flow through the other. It would take energy to build up the magnetic field, but since current can now flow in the other wire, an equal and opposite current flows in the other wire. Now no net current flows through both wires together, and there is no net magnetization of the core. The core only is magnetized to the extent that the two wires do not exactly contain the same magnetic flux, and since they are twisted intimately around each other, the two wires share almost 100% of their flux. Because of this, a current in one wire can induce a current in the other with hardly any magnetizing of the core at all. If the two windings are separated, we can consider two windings as parts of a "magnetic circuit" with the core being the path of the circuit that the magnetic field lines travel. A winding has an electric current flowing through it with a number of turns, called "magnetomotive force." This induces a magnetic field according to Ampere's law in the toroid's medium (the magnetic circuit medium) with the magnetic flux given by the ratio of the magnetomotive force and the reluctance of the circuit. This is akin to Ohm's law for electric circuits. The idea of "reluctance" is related to exactly above where it takes energy to establish a magnetic field in a medium, and so when a voltage is applied to an inductor, it takes more time ("is reluctant") for a magnetic field to be established. The magnetic flux can then induce a voltage (and therefore a current) into the secondary winding, with the current having a magnetomotive force that cancels out that of the first winding. Because the windings are separated, the flux is conducted in the core between the two separated windings, are opposed to the case where the two wires are intimately wrapped around each other and the flux hardly needs to be established at all, and so the flux established in the core may be significant and could potentially even saturate the core material if the field is high enough. This is why in many transformers windings, if they are not twisted together (which can cause capacitance between the windings, and so must be wound as transmission-line transformers to prevent parasitic effects), are usually either concentric (wound one on top of the other), or kept as close as practically possible.
I think the easiest way to explain this is that the electric field E is perpendicular to the Magnetic Field H. The electric field runs in the same directions as the wires. Because of the time changing current in the primary windings, this will induce a time changing magnetic field. Since the wires are wrapped around the toroid, the time changing magnetic field has to be perpendicular to the windings, or, in the toroid. If other windings are placed on the toroid, similar to the primary winds, the time changing magnetic field will induce a current on those windings. All of the these Physics are explained in the Mathematics of the the 4 Maxwell equations.
Thank You very Much ! When Youi Talk Abbout The Old Toroids And Other Stuff, It Would Be Cool That You Put Some Examples In The Video So We Can See What You Mean, Video Is Reaally Good
1) "Mysterious action at a distance" is what we call radio, which was characterized by Maxwell. "Spooky action at a distance" was Einstein's name for quantum effects that appear not to be restricted by the speed of light. Much different things.
The last sentence is the punch. "We will make sure The University of Michigan Amateur radio club is up to date"😀 Dave, you are rocking here. And the poor Maxwell came out of the grave today only to commit suicide 🙈 De VU2RZA
I've been watching your videos for years and excellent/informative is my best way of describing them. Indeed, your videos helped inspire me to get my amature extra license. However, the constantly moving camera work in your latest videos is too distracting. Especially on a large screen TV.
"Spooky", later referred to as "mutual conductance". There was an old wives tale that went around about how you could "effectively" increase your output power without any amplification by stacking toroids. Not true, it actually takes away from effective radiated power. Accept, if done right, It makes a great balun and gives full transfer of energy out to the world 👍😁.
The only thing stacking toroids does, is to increase the amount of current it takes to saturate the core by decreasing the flux density, at the cost of increasing the magnetic losses. If a core isn't saturating, it doesn't need to be doubled.
![[#2024MAMA] ROSÉ (로제), Bruno Mars - APT. | Mnet 241122 방송](http://i.ytimg.com/vi/dgGqD28J6aQ/mqdefault.jpg)
Great topic!!! The rise of winders is here, but I am not sure what I'm doing, so your timing is perfect!!!
Maxwell's equations actually require some advanced math. To keep things simple, I just say:
1. Putting a voltage across (or a current through) a wire creates an electric field.
2. The changing electric field creates a magnetic field. In a toroid, this field is ring shaped, inside the toroid itself.
When you wrap ANOTHER coil on the toroid, the same magnetic field is inside. This leads to:
3. A changing magnetic field creates an electric field, which can be picked up by a wire.
Which is what you said, I'm just summarising here.
Like your new format. Explain how toroids work in a RFI and choke configuraton.
Dave too is wondering on the subject 😊
De VU2RZA
You probably have chokes with two identical windings in mind. If it is inserted into a two wire line, the wanted current flows through both windings in an opposite direction. The magnetic fields cancel each other, so the inductance for the wanted current is zero. Unwanted common mode current, on the other hand, encounters high inductance, which limits its intensity.
Another case - toroids beaded on a coxial cable. A coaxial cable behaves as three conductors at RF: the inner one, the inner surface of the braid and the outer surface of the braid. Ferrite toroids or tubes beaded on a coax increase the inductance of the outer surface, where unwanted, unbalanced and RFI currents flow. The inductance of the two other conuctors is not affected.
4:15 Two types of material for toroids (and other shapes of RF cores) are used:
A/ ferrite - a sort of magnet permeable ceramic, which is sintered at high temperature and treated in a special manner. It is not powdered nor glued. If such core is heated above certain temperature (e.g. by excessive RF power losses), it loses its magnetic properties forever.
B/ carbonyl - powdered iron mixed with glue and hardened. If it is overheated and cooled again, its magnetic properties return back.
It is not necessary for a toroid to be made of a magnetizable material to be useful for confining the magnetic field. A solenoid (or long thin coil of wire) has its magnetic field mostly confined to the inside of the solenoid. Magnetic field lines are always closed, and so in a linear solenoid even without any magnetic medium inside it, the lines loop back around the outside of the solenoid to the other side. If the solenoid is bent into a circle so that the end of the solenoid meets the front, the magnetic field lines in the loop directly back to the other side crossing the minimum distance because the ends of the solenoid nearly meet. In fact, at high frequencies, a solenoidal form made using a ceramic toroid is sometimes used that is non-magnetic.
In an ordinary inductor, a magnetic field must be established in the magnetically permeable medium inside the toroid (whether or not it is air or iron powder, ferrite, etc.) in order for a current to flow in the wire. The current rises in time in proportion to the voltage and inversely proportional to the inductance. As the current rises, energy builds up in the magnetic field in the core.
Now say we take two wires and twist them together and thread them together around the core. Let's say we apply current to only of the wire, and leave the other wire open circuit. This is the same as only having one wire, and again it takes energy to build up the magnetic field in the core and for the current to flow. But let's say we now short the other wire. Now when apply a current to the other wire, a current can flow through the other. It would take energy to build up the magnetic field, but since current can now flow in the other wire, an equal and opposite current flows in the other wire. Now no net current flows through both wires together, and there is no net magnetization of the core. The core only is magnetized to the extent that the two wires do not exactly contain the same magnetic flux, and since they are twisted intimately around each other, the two wires share almost 100% of their flux. Because of this, a current in one wire can induce a current in the other with hardly any magnetizing of the core at all.
If the two windings are separated, we can consider two windings as parts of a "magnetic circuit" with the core being the path of the circuit that the magnetic field lines travel. A winding has an electric current flowing through it with a number of turns, called "magnetomotive force." This induces a magnetic field according to Ampere's law in the toroid's medium (the magnetic circuit medium) with the magnetic flux given by the ratio of the magnetomotive force and the reluctance of the circuit. This is akin to Ohm's law for electric circuits. The idea of "reluctance" is related to exactly above where it takes energy to establish a magnetic field in a medium, and so when a voltage is applied to an inductor, it takes more time ("is reluctant") for a magnetic field to be established. The magnetic flux can then induce a voltage (and therefore a current) into the secondary winding, with the current having a magnetomotive force that cancels out that of the first winding. Because the windings are separated, the flux is conducted in the core between the two separated windings, are opposed to the case where the two wires are intimately wrapped around each other and the flux hardly needs to be established at all, and so the flux established in the core may be significant and could potentially even saturate the core material if the field is high enough.
This is why in many transformers windings, if they are not twisted together (which can cause capacitance between the windings, and so must be wound as transmission-line transformers to prevent parasitic effects), are usually either concentric (wound one on top of the other), or kept as close as practically possible.
Spooky action at a distance. 😊
I think the easiest way to explain this is that the electric field E is perpendicular to the Magnetic Field H. The electric field runs in the same directions as the wires. Because of the time changing current in the primary windings, this will induce a time changing magnetic field. Since the wires are wrapped around the toroid, the time changing magnetic field has to be perpendicular to the windings, or, in the toroid. If other windings are placed on the toroid, similar to the primary winds, the time changing magnetic field will induce a current on those windings. All of the these Physics are explained in the Mathematics of the the 4 Maxwell equations.
Thank You very Much !
When Youi Talk Abbout The Old Toroids And Other Stuff, It Would Be Cool That You Put Some Examples In The Video So We Can See What You Mean, Video Is Reaally Good
Good job Dave...
I have an idea for Ask Dave. How to hide towers from XYL’s.
Rent space in your neighbors property!
1) "Mysterious action at a distance" is what we call radio, which was characterized by Maxwell. "Spooky action at a distance" was Einstein's name for quantum effects that appear not to be restricted by the speed of light. Much different things.
These comments are as educational as the video. Thank you everyone!
Fantastic tutorial Dave, Thank you!!!.
8:50 Poor J. C. Maxwell ! 😪
Alternating current always present
The last sentence is the punch. "We will make sure The University of Michigan Amateur radio club is up to date"😀
Dave, you are rocking here.
And the poor Maxwell came out of the grave today only to commit suicide 🙈
De VU2RZA
I've been watching your videos for years and excellent/informative is my best way of describing them. Indeed, your videos helped inspire me to get my amature extra license. However, the constantly moving camera work in your latest videos is too distracting. Especially on a large screen TV.
Thanks for your feedback. My assistant and I will figure out a way to solve the problem. 73, Dave, KEØOG
@@davecasler Thank you, Dave! Your videos are invaluable.
The way ther wrapped matters
The fluxation will b in winding direction... The direction will follow the wrapp
"Spooky", later referred to as "mutual conductance". There was an old wives tale that went around about how you could "effectively" increase your output power without any amplification by stacking toroids. Not true, it actually takes away from effective radiated power. Accept, if done right, It makes a great balun and gives full transfer of energy out to the world 👍😁.
OM tale more likely 😆 *Except
The only thing stacking toroids does, is to increase the amount of current it takes to saturate the core by decreasing the flux density, at the cost of increasing the magnetic losses. If a core isn't saturating, it doesn't need to be doubled.
He torid is 1 winding itself...just like a transformer input transformer are 1 wrapp...
The type of coiled changes the field flux
A coil will natural produce voltage ...
Flux action fluxation
Always induction
I am still confused. More confused now than before this video📻🎧
It's tluxatiom