New PI technology proposals.

[Aziz]

To ease the imagination of the idea, I will put the schematics of this idea. Then you can make your own thoughts.

Aziz

But the idea is somehow genius that it never considered at this unconventional way.

The following picture shows the MONO coil configuration.

[Aziz]

Hi Carl,

No, it is the di/dt of the turn-off that kicks the target. The flyback voltage is a side effect (L*di/dt) that is only useful near the end, where we look at it for small variations.
- Carl

We are talking almost about the same thing. Almost.

Let's give to some process points names:
toff = exact turn-off time
toff- = the time just before turn-off
toff+ = the time just after turn-off

At toff we have maximum flyback voltage. The magnetic field energy is still there and the nature is getting into heavy stress. It is protesting. The coil says: "Damn, I have loaded much energy. Where to damp it?".

At toff+ starts the damping resistor to convert this magnetic field energy into heat. The current through the coil and damping resistor, in which is converting to heat, is killing the magnetic field density around the coil. The target see's a magnetic flux change! The dI(t)/dt in the damping process is necessary, to convert this energy as fast as possible. Now the damping resistor gets into heavy stress (producing heat). But it is his profession to do this and the resistor likes this process. The more the flyback voltage, the more the heat production (until the resistor goes up in smoke).

Sorry, but it is a faster turn-off settling that produces the higher flyback, not the other way around.

You'll need to post a schematic to clarify, but I suspect you are getting a faster turn-off simply because of L/4.

- Carl

At toff, the coil surrounding has the same magnetic field energy got from the half part of the coil (L/4). At toff we have also now the full coil windings (L=300µ). Now, it is the same state as the full coil would do anyway. The turn-off process applies to both alternatives: either single full coil or half driven coil plus the step-up conversion on the other end. They have to damp the same magnetic field energy. Who willl win the race?

Now the benefits of the lucky side effects (nice to have effects):
Mosfet see's only the half coil capacitance (switching of course faster off). Mosfet see's only less coil voltage while the damping resistor see's the full coil voltage.
Damping process is now 4 times efficiently.


Who can follow me?

Aziz

[Aziz]

I have the feeling of you guys do not trust in theory and SPICE simulations. During the last days, I also did not. Because it changes my knowledge about PI detectors. The theory is older than 100 years old. It is well proofen.

But I have learned much more with SPICE simulations rather than with soldering iron. Particularly when the SPICE simulation says "The flyback process is kicking the target! That's matters!". And you can see the targets induced voltage and current. Provided that, you have modeled the circuit right.

So the theory says, "practice won't work without my permission. If so, then practice is believing it has the permission for.".


Just some advises for practical testing:
Do not try this without the background knowledge. You may fry your circuit or getting electric shocks from the coil ends otherwise.

Aziz

[Carl-NC]

The flyback voltage isn't an artifact! It is an essential process for "kicking the target". It is the process (damping), where the target's eddy currents will be actually generated.

No, it is the di/dt of the turn-off that kicks the target. The flyback voltage is a side effect (L*di/dt) that is only useful near the end, where we look at it for small variations.

Of course, during TX on-time there is also some eddy currents in the target. But they have no real role in the PI technology as supposed. The effects of the damping process predominating this.

Finally, someone who agrees with me on this! Yes, the "on-time" eddy currents are negligible, even if the current is still ramping up at the point of turn-off.

The higher the flyback voltage is, the more efficiently and faster will be the damping process.

Sorry, but it is a faster turn-off settling that produces the higher flyback, not the other way around.

The transmitter coil will therefore be a splitted winding coil. Either a center-tapped or a step-up coil. The step-up coil will produce high flyback voltages beyond the hell. ... My proposal is using only the small part of the splitted coil. If we use the center-tapped coil, this will allow double current flow (half resistance -> I = 2 A) on a half coil (Lhalf = 300µH/4 = 75µH).

You'll need to post a schematic to clarify, but I suspect you are getting a faster turn-off simply because of L/4.

- Carl

[ToyMaker]

Some guy, a lot smarter than me, said,

"In theory, theory and practice are the same, in practice, they are not".

What this means in the real world is that there can be a BIG step
between the science (theory) of a thing and the engineering (practice)
of it.

If I ever get heat in my lab (it's 20F/-6.7C in there right now ) I'll try
to engineer some of this science

Aziz, keep up the good work. I have much enjoyed following your posts.





robotic regards,

tom

[Aziz]

Hi Qiaozhi,

The main question here is - have you actually tried this in practice?

Exploring your new ideas with a simulator is extremely useful, but you must also test these in the real world. Many "remarkable breakthroughs" have been announced in the past, only to fail miserably when tested for real.
An element of caution is needed here ... remember the experience you had with the induction balance breakthrough.

gwzd said that history is not his favorite subject, but without studying history we are doomed to make the same mistakes over and over again.

I haven't tried the idea yet. You know, I am a very poor guy, who hasn't the means for. I made extensive SPICE circuit simulations. The theory behind the idea is just physics. The theory states some good ways. And the circuit simulations are showing the expected results. By the way, I haven't fired my soldering iron for month.

One thing I don't know yet, whether the clamping diodes will survive on such high voltages! But this is quite trivial to test..

You all are welcome to test this proposal.

Aziz

[Tinkerer]

Hi Carl,

we have to recapitulate and rewrite some topics on the PI technology.

I have a totally different sight of this. This is the reason for, why nobody found the evident solution till now. I am sure, this will bring some new products and coils in the future. (And Mr. Tesla would be very likely proud of me.)



The flyback voltage isn't an artifact! It is an essential process for "kicking the target". It is the process (damping), where the target's eddy currents will be actually generated.

The TX on-time is merely used, to build a magnetic energy around the transmitter coil. The inductor is a typical energy conserving element (L,C). Once loaded the element with magnetic energy (E=0.5*L*I*I), this energy is not lost immediately after switch off-time. The nature physics does not like any physical changes when in some stable stationary state. As a consequence, the coil current wants to flow in the same direction as before or the magnetic field wants to stay at same state as before. This is the reason for high flyback voltage when the nature is getting stressed! Is causes also some stress reaction.

Of course, during TX on-time there is also some eddy currents in the target. But they have no real role in the PI technology as supposed. The effects of the damping process predominating this.

The genuis of this idea is to use the flyback voltage more efficiently. So a fast conversion from magnetic energy into heat is necessary. As you convert energy in the nature, the nature isn't making any stress. The nature likes energy conversion (we are also somehow energy converters - aren't we?).
The higher the flyback voltage is, the more efficiently and faster will be the damping process. A 400 V IRF740 for instance is used, to manage a ~1.6 kV coil voltage! And this without going beyond the avalanche breakdown voltage. This high coil voltage is intentionally generated. The result is, I can decay much faster than the natural decay behaviour. This will have the effect of stimulating the target more effective and will generate more eddy currents.

We can achieve just with simple anti-parallel clamping diodes superior early sampling timings on MONO coils. Even they are clamped.

New PI coils must be developed by the industry to use the benefits of this wonderful finding. I call this type of coils "Tesla coil". The function of the new coil is like the original Tesla coil: producing high voltages! The transmitter coil will therefore be a splitted winding coil. Either a center-tapped or a step-up coil. The step-up coil will produce high flyback voltages beyond the hell. A center-tapped coil will have the best performance due to the differential signal line benefits. So the coil cabling can be realized as a twisted-pair cabling. No shielding of the cabling is required in this case and will lower the capacitive load on the coil.


Bbsailor has kicked this wonderful finding. Many thanks to him. He just wished to have a faster sampling. Now, we all will have this feature.

Aziz

Have you tried this with a real coil?
Tinkerer

[Qiaozhi]

The main question here is - have you actually tried this in practice?

Exploring your new ideas with a simulator is extremely useful, but you must also test these in the real world. Many "remarkable breakthroughs" have been announced in the past, only to fail miserably when tested for real.
An element of caution is needed here ... remember the experience you had with the induction balance breakthrough.

gwzd said that history is not his favorite subject, but without studying history we are doomed to make the same mistakes over and over again.

[Aziz]

Hi Palamedes,

Hi Aziz,

small reminder about the limit value (100 µT) that the International Radiation Protection Association (IRPA) recommends not be exceeded in exposure of populations to RF magnetic fields.

What level of RF MF would you expect from 1.6 kV coil voltage?
http://www.scantech7.com/EMF_RF_Elec...ety_Levels.htm

there is almost no difference to the common PI's. Same magnetic field energy will be exposed. If we have a coil current of 1 A and 300 µH coil, we would have the magnetic energy of E = 0.5*300µH*1A*1A = 0.00015 J (Joule).

My proposal is using only the small part of the splitted coil. If we use the center-tapped coil, this will allow double current flow (half resistance -> I = 2 A) on a half coil (Lhalf = 300µH/4 = 75µH).
The exposed magnetic energy is: E = 0.5*75µH*2A*2A = 0.00015 J. (1 J = 1 VAs = 1 Ws). So same amount of energy will be exposed. (MOSFET's Rdson and other effects neglected).

As a comparison to the energy exposed: 1 J = 1 Ws = 1 VAs, 1 V with 1 A current and 1 second duration on a resistance will produce the same energy of 1 J. Look at the figures above! It is only a fraction of this.

We are not interested in emitting EMF. The high voltage is used to kill the magnetic energy as quick as possible. This has a law of square of coil voltage (P = U*U/Rd ). The magnetic energy E is then converted to heat energy. If we double the coils flyback voltage, the effect is 4 times! This makes the damping process really fast.

Some PI's are using more coil currents. They exceed the recommendation anyway. But this has the benefit of producing much higher flyback voltages. I tend to use lower inductivities (12..75 µH).


Aziz

[Palamedes]

Hi Aziz,

small reminder about the limit value (100 µT) that the International Radiation Protection Association (IRPA) recommends not be exceeded in exposure of populations to RF magnetic fields.

What level of RF MF would you expect from 1.6 kV coil voltage?

http://www.scantech7.com/EMF_RF_Electric_Field_Safety_Levels.htm

[Aziz]

Hi Carl,

we have to recapitulate and rewrite some topics on the PI technology.

I have a totally different sight of this. This is the reason for, why nobody found the evident solution till now. I am sure, this will bring some new products and coils in the future. (And Mr. Tesla would be very likely proud of me.)

The flyback voltage is an artifact of pulsing the coil, and not something you can "use" to speed things up. Fundamentally, di/dt is controlled by the 'on' current, the inductance, and the damping resistor (which is, in turn, dependent on capacitance). Probably you are changing one of these, and getting a faster di/dt and a higher resulting flyback.

- Carl

The flyback voltage isn't an artifact! It is an essential process for "kicking the target". It is the process (damping), where the target's eddy currents will be actually generated.

The TX on-time is merely used, to build a magnetic energy around the transmitter coil. The inductor is a typical energy conserving element (L,C). Once loaded the element with magnetic energy (E=0.5*L*I*I), this energy is not lost immediately after switch off-time. The nature physics does not like any physical changes when in some stable stationary state. As a consequence, the coil current wants to flow in the same direction as before or the magnetic field wants to stay at same state as before. This is the reason for high flyback voltage when the nature is getting stressed! Is causes also some stress reaction.

Of course, during TX on-time there is also some eddy currents in the target. But they have no real role in the PI technology as supposed. The effects of the damping process predominating this.

The genuis of this idea is to use the flyback voltage more efficiently. So a fast conversion from magnetic energy into heat is necessary. As you convert energy in the nature, the nature isn't making any stress. The nature likes energy conversion (we are also somehow energy converters - aren't we?).
The higher the flyback voltage is, the more efficiently and faster will be the damping process. A 400 V IRF740 for instance is used, to manage a ~1.6 kV coil voltage! And this without going beyond the avalanche breakdown voltage. This high coil voltage is intentionally generated. The result is, I can decay much faster than the natural decay behaviour. This will have the effect of stimulating the target more effective and will generate more eddy currents.

We can achieve just with simple anti-parallel clamping diodes superior early sampling timings on MONO coils. Even they are clamped.

New PI coils must be developed by the industry to use the benefits of this wonderful finding. I call this type of coils "Tesla coil". The function of the new coil is like the original Tesla coil: producing high voltages! The transmitter coil will therefore be a splitted winding coil. Either a center-tapped or a step-up coil. The step-up coil will produce high flyback voltages beyond the hell. A center-tapped coil will have the best performance due to the differential signal line benefits. So the coil cabling can be realized as a twisted-pair cabling. No shielding of the cabling is required in this case and will lower the capacitive load on the coil.


Bbsailor has kicked this wonderful finding. Many thanks to him. He just wished to have a faster sampling. Now, we all will have this feature.

Aziz

[Carl-NC]

The flyback voltage is an artifact of pulsing the coil, and not something you can "use" to speed things up. Fundamentally, di/dt is controlled by the 'on' current, the inductance, and the damping resistor (which is, in turn, dependent on capacitance). Probably you are changing one of these, and getting a faster di/dt and a higher resulting flyback.

- Carl

[Aziz]

Hi gwzd,

the main reason for the idea is to damp the flyback voltage as fast as possible. As the damping resistor (Rd) is only a function of the coils inductivity and capacitance (+parasitic capacitances), we can not change the damping resistor for critical damping of the coil. It is fixed to the transmitter parts system.

The magnetic energy E = 0.5*L*I*I built on the transmit on phase must be converted to heat on the coils resistive elements (damping resistor, coils resistor, coil cables, ..).

This can be achived effectively by using a higher flyback voltages to allow more current flow through the damping resistor.
P = I*I*Rd = U*U/Rd.

Then the magnetic energy will be converted much faster to heat and will allow decaying the high voltage quicker. This makes the early sampling faster and has also the ability to cause higher target signal stimulation (higher dI(t)/dt). Doubling the flyback voltage has an effect of 4 times!!!

But there are more inherent effects that have big benefits!

I hope, I have called your interest a bit to dig in the history...

Aziz

[gwzd]

Hi gwzd,



you need the chronology order of the information on the forum, I have posted there. Then you can see the birth of the idea and this gives the opportunity to understand it.

Regards,
Aziz

I usually skip to the end! History is not one of my favorite subjects ;-)
Regards,

[Aziz]

Hi gwzd,

Why? You are going to tell us here anyway. You just can't resist, can you?
Regards,

you need the chronology order of the information on the forum, I have posted there. Then you can see the birth of the idea and this gives the opportunity to understand it.

Regards,
Aziz