Guys, I hate to say, but can you people please take your definition and theory debates elsewhere...I'm watching this thread almost 24/7 for any input into my project and you guys are just debating back and forth. Share your knowledge please! Answer my questions

 

The answer is: If it radiates, it is EMF, Electro-Magnetic Radiation.

How can I create a magnetic frield without making a significant electric field so that I don't get into trouble with the FCC?

If the field strength does not vary with time, there is no problem.

You are looking into wireless power transmission. If you have a real interest, learning all you can about electronics and physics is a good start. About the only idea to even appear feasible is through microwaves - http://en.wikipedia.org/wiki/Microwave_transmission

I would not care to be in the RF field transmitting significant power. At one school I attended in the Navy, there was an operating SPS-48 radar on one building. The surrounding trees were dead where the beam passed. A bird landing in the beam path lasted two sweeps before becoming well done.

 

The answer is: If it radiates, it is EMF, Electro-Magnetic Radiation.

If the field strength does not vary with time, there is no problem.

You are looking into wireless power transmission. If you have a real interest, learning all you can about electronics and physics is a good start. About the only idea to even appear feasible is through microwaves - http://en.wikipedia.org/wiki/Microwave_transmission

I would not care to be in the RF field transmitting significant power. At one school I attended in the Navy, there was an operating SPS-48 radar on one building. The surrounding trees were dead where the beam passed. A bird landing in the beam path lasted two sweeps before becoming well done.

Hi, thanks for your reply. I'm not sure if you are aware of what the M.I.T guys did, but it was super safe. In fact, so safe that it doesn't even affect other devices, let alone living biological organisms. I want to this so I can power all of the electronics in a typical house living room or bedroom. It is possible, and it has been done. Just figuring out how they did so I can replicate it for my own amusement

As for microwaves, it is efficient and good, but its not for near-distance transmission. It's more like long distance high efficiency transmission, but I'm not looking into that. Somebody else can develop that to deliver electricity to homes ,and I'll use that signal to make wireless power for whatever that is inside the homes hehe So far, it's been a hassle. Been reading everything and taking in everyone's knowledge on this topic. Need more doh...it's not enough.

 

I suspect the MIT experiment used a lot more magnetic coupling than RF just because it didn't interact with other systems or biology. I've seen medical devices that warmed tissue (I had a sprained ankle many decades ago) that used a frequency similar to the MIT (I think). You don't want this with any wireless system.

Whatever is used, think inverse square law, which is the real problem to overcome for any wireless system. This means to some extent the signal must be directional.

As many people who are working on this if it were easy it would have been solved by now. It definitely requires a wide variety of disciplines, so mondo reading required.

 

I suspect the MIT experiment used a lot more magnetic coupling than RF just because it didn't interact with other systems or biology. I've seen medical devices that warmed tissue (I had a sprained ankle many decades ago) that used a frequency similar to the MIT (I think). You don't want this with any wireless system.

Whatever is used, think inverse square law, which is the real problem to overcome for any wireless system. This means to some extent the signal must be directional.

As many people who are working on this if it were easy it would have been solved by now. It definitely requires a wide variety of disciplines, so mondo reading required.

Thank you Bill. Can you please verify why a parallel resonant tank circuit is more efficient than a series resonant circuit? I need to make sure I understand everything, so please understand me and I'm not trying to annoy you with these type of questions.

 

To a limited extent (very limited) parallel resonance is a form of storage. In a perfect system (that doesn't exist) they would swap voltage/current forever. This isn't the case for series resonant.

Change of subject that relates a little. With a superconductor if you create a current in a superconducting coil, then close the circuit in that coil with the current still flowing, it will last as long as the superconductor circuit is intact. The energy is stored as magnetic energy, and you have a permanent magnet for that duration.

 

To a limited extent (very limited) parallel resonance is a form of storage. In a perfect system (that doesn't exist) they would swap voltage/current forever. This isn't the case for series resonant.

Change of subject that relates a little. With a superconductor if you create a current in a superconducting coil, then close the circuit in that coil with the current still flowing, it will last as long as the superconductor circuit is intact. The energy is stored as magnetic energy, and you have a permanent magnet for that duration.

Yes, our professor showed us the superconductor behaviour of some material and the current runs forever because there is 0 resistance.

So Bill, my parallel tank circuit is obviously not a perfect system, so it's signal will die out pretty fast. My question is: Will my AC power supply simply re-supply the LC circuit with a new signal if the old resonant oscillating signal dies out due to resistance when the capacitor and inductor can't exchange anymore? Will it force the capacitor to charge from the AC supply this time instead of from the inductor??

 

I would not care to be in the RF field transmitting significant power. At one school I attended in the Navy, there was an operating SPS-48 radar on one building. The surrounding trees were dead where the beam passed. A bird landing in the beam path lasted two sweeps before becoming well done.

We had the old SPS-40. 200kW (peak) 400Mhz. We would stop rotation and use manual control to paint something with it. (Like a snooping AGI). In about 10 seconds they would turn-tail and scoot. High power RF is dangerous, using it to transmit power would be folly.

 

We had the old SPS-40. 200kW (peak) 400Mhz. We would stop rotation and use manual control to paint something with it. (Like a snooping AGI). In about 10 seconds they would turn-tail and scoot. High power RF is dangerous, using it to transmit power would be folly.

Yes, of course! The only method which I see is plausible for wireless power transmission for long distance is using microwaves in the RF spectrum. It's safe and efficient. For home-size wireless power, magnetic coupling via magnetic fields is plausible too.

 

Yes, of course! The only method which I see is plausible for wireless power transmission for long distance is using microwaves in the RF spectrum. It's safe and efficient. For home-size wireless power, magnetic coupling via magnetic fields is plausible too.

Power transmission by wires is safer and a lot more efficient. In a few years I believe we will have room temperature superconductors that can handle the high currents needed for power transmission. This is real research by people with more brains than I will ever have.

http://www.theoryinstitute.org/~its/rts/abstracts.html


PS. I should explain that a AGI is a thing, not a person.

 

It's safe and efficient

If you are alive and in the beam path, it is anything but safe. See remarks about radars in above posts. (The AGI crews were getting hot and in some danger of suffering permanent harm. You did not actually kill anyone in the Cold War, but you could come reasonably close.)

And it's like all other EM radiation as it obeys the inverse square law.

You can diminish the lethality of EMR by using a diffuse beam to keep field strength low per unit area, but that demands a huge antenna to receive significant power.

 

Okay fellow members, I would like to wash away some confusion here, and then get on with the topic of the thread and have some more physics knowledge on this:

A magnetic field doesn't propagate. Hence, it does not obey the inverse square law. It has its own law, called the inverse cube law for magnetic strength disappearance. An electromagnetic wave obeys the inverse square law, as well as the electric field too. However, my main interest is magnetic field coupling, so the inverse square law does not apply to my situation.

Secondly, I wish to make clear that you do not lose huge amounts of power with the inverse cube law in magnetic coupling. You just lose coupling strength when you're trying to couple two coils. My objective is to send minimum input current and set up a strong magnetic field via resonance. Once established, use a square wave output to keep that magnetic field up and running so I can induce a strong current into my secondary coil. My only loss here was to set up the field, which took some little amount of current to do so. Then resonance builds it to make it really strong, and then I induce it to get a strong current to power my load. I got a lot for very little.

In EM radiation, you lose power with inverse square law. That means you need to pump serious watts out just to get a couple watts at the receiving end. This is not the case with magnetic field coupling. You send couple watts, and if you're out of the vicinity of the magnetic field, then you lose those couple watts. But if you're within the vicinity of it, then you can take it with some acceptable efficiency. The stronger the magnetic field, the greater the vicinity, and hence greater distance for power transfer. I haven't tried it yet, but it seems good on paper so far.

Do you guys understand what the difference is and what I'm trying to do? A lot of you responded with radio, but it seems like I'm not being clear enough. Was the written clear or still am I missing something?

 

Okay fellow members, I would like to wash away some confusion here, and then get on with the topic of the thread and have some more physics knowledge on this:

A magnetic field doesn't propagate. Hence, it does not obey the inverse square law. It has its own law, called the inverse cube law for magnetic strength disappearance. An electromagnetic wave obeys the inverse square law, as well as the electric field too. However, my main interest is magnetic field coupling, so the inverse square law does not apply to my situation.

Secondly, I wish to make clear that you do not lose huge amounts of power with the inverse cube law in magnetic coupling. You just lose coupling strength when you're trying to couple two coils. My objective is to send minimum input current and set up a strong magnetic field via resonance. Once established, use a square wave output to keep that magnetic field up and running so I can induce a strong current into my secondary coil. My only loss here was to set up the field, which took some little amount of current to do so. Then resonance builds it to make it really strong, and then I induce it to get a strong current to power my load. I got a lot for very little.

In EM radiation, you lose power with inverse square law. That means you need to pump serious watts out just to get a couple watts at the receiving end. This is not the case with magnetic field coupling. You send couple watts, and if you're out of the vicinity of the magnetic field, then you lose those couple watts. But if you're within the vicinity of it, then you can take it with some acceptable efficiency. The stronger the magnetic field, the greater the vicinity, and hence greater distance for power transfer. I haven't tried it yet, but it seems good on paper so far.

Do you guys understand what the difference is and what I'm trying to do? A lot of you responded with radio, but it seems like I'm not being clear enough. Was the written clear or still am I missing something?

In practice it won't make any difference past a few feet of open air.
http://en.wikipedia.org/wiki/Wireless_energy_transfer

I work with high flux magnetic fields to generate and manipulate ion beams (1 Tesla+) 10 ton electro-magnets. Pass 6 feet they only cause a small deflection on a crt screen. A 6 inches it will crush your hand if your holding a wrench between it.

Lab example:

 

I once was installing radio controls in a plant that was using 200,000 amps to extract aluminum from bauxite. That current produced a measly 200 gauss (10,000 gauss = 1 tesla) yet because the conductors passed underground and beneath the restrooms, the field was strong enough to hold the stall doors open with a force of about 50 lbs. I was told about a construction worker who was carrying a pipe and walked too close to the conductor and had the pipe taken away from him. Just walking through the plant would cause one's keys to move in one's pocket and a metal toolbox that was being carried to constantly rotate back and forth.

Since our transmitters used ferrite cores, they would saturate, detune the amplifier and reduce the range when close to the conductors even though they were enclosed in an aluminum box which unfortunately is transparent to magnetic fields. We switched to mu metal enclosures which didn't help at all. We certainly were able to feel the effects more than a few feet away.

 

I once was installing radio controls in a plant that was using 200,000 amps to extract aluminum from bauxite. That current produced a measly 200 gauss (10,000 gauss = 1 tesla) yet because the conductors passed underground and beneath the restrooms, the field was strong enough to hold the stall doors open with a force of about 50 lbs. I was told about a construction worker who was carrying a pipe and walked too close to the conductor and had the pipe taken away from him. Just walking through the plant would cause one's keys to move in one's pocket and a metal toolbox that was being carried to constantly rotate back and forth.

Since our transmitters used ferrite cores, they would saturate, detune the amplifier and reduce the range when close to the conductors even though they were enclosed in an aluminum box which unfortunately is transparent to magnetic fields. We switched to mu metal enclosures which didn't help at all. We certainly were able to feel the effects more than a few feet away.

Not to sound rude or anything, what's your point/message? That weak-depicted magnetic fields are in fact much much stronger despite being very low in magnitude of Teslas/Gauss?

 

The current flowing through the conductors to the magnet (Or any device) can induce magnetic flux in your keys or tool box.

It is like walking into a transformer and BECOMING the core.

 

Oh, that's cool! Maybe its because their coil was so large that it circled around the whole entire plant beneath the surface?

 

I know what your thinking...

But remember, that is not a safe place for families or magnetic media.

 

Not to sound rude or anything, what's your point/message? That weak-depicted magnetic fields are in fact much much stronger despite being very low in magnitude of Teslas/Gauss?

I suspect the 1 tesla field was the result of various means of concentrating the field in a small volume. Possibly the reason the field dropped off so rapidly was due more to leaving the zone where it was focused. I was trying to point out that even a field which has not been concentrated may still be storng enough to cause significant effects.

How many amps were needed to generate the 1 tesla field?

 

How many amps were needed to generate the 1 tesla field?

From above,

I once was installing radio controls in a plant that was using 200,000 amps to extract aluminum from bauxite.