New advanced PI project

[willybayot]

.ASC file missing

[Tinkerer]

.ASC file missing

OK, here is the .asc file

[ivconic]

"......My TX design has been running for a few years. As I am 79 years old now I decided to post it now, before it is too late..."

Excuse me for being so peristent, i am very interested in one thing; is your design has been running for a few years in simuator or in real world?

"...now I decided to posti it now..."

?!??
Where? When?
Schematic, video... or at least a photo of ready device...
But if you don't intend to post the schematic, pcb, photos and videos of device in action; than say so.
Playing in simulators and posting only skim parts of that is one thing and what you promised in quoted text is quite another thing.

[Tinkerer]

"......My TX design has been running for a few years. As I am 79 years old now I decided to post it now, before it is too late..."

Excuse me for being so peristent, i am very interested in one thing; is your design has been running for a few years in simuator or in real world?

"...now I decided to posti it now..."

?!??
Where? When?
Schematic, video... or at least a photo of ready device...
But if you don't intend to post the schematic, pcb, photos and videos of device in action; than say so.
Playing in simulators and posting only skim parts of that is one thing and what you promised in quoted text is quite another thing.

For a schematic or video you will have to exercise your patience for a while.
I intend to explain the functioning of an advanced, square current wave PI. Without understanding how it works, a schematic or PCB or video will be quite useless to you.

[ivconic]

Cool!
Knowing that there is still a light at the end of the tunnel gives me enough patience to wait until the big flood and back!


P.S.
When you came back from Venezuela you were 83, and now you claim to be 79! ??
What's your secret?

[Tinkerer]

Cool!
Knowing that there is still a light at the end of the tunnel gives me enough patience to wait until the big flood and back!


P.S.
When you came back from Venezuela you were 83, and now you claim to be 79! ??
What's your secret?

I am getting younger every day. Soon I will be wearing Pampers again.

[ivconic]

[Tinkerer]

Here is a more useful YouTube: This YouTube demonstrates the interaction between a magnet and a copper target.
https://youtu.be/sENgdSF8ppA

[Tinkerer]

Flattop target Eddy currents
What happens inside a target when we hit it with our magnetic TX pulse?
We start by looking at the simulation of the traditional PI with the Flattop TX pulse.
The we will look at the simulation of the current square wave TX pulse and how different it affects the eddy currents in the target.

[Tinkerer]

When we look at the eddy currents in the targets, at the time between 1ms to 1.2ms in the simulation above, we see how the eddy currents build up in targets with different Time Constants (TC).
In the 1us target the eddy currents build up and then decay. By the time the TX ramp reaches Flattop the eddy currents are nearly gone. The rate of change of the transition between the ramp and the Flattop again induces some eddy currents that decay very quickly.
In the target with TC’s of 5us and 10us, something similar happens with the time of eddy current decay proportional the TC’s.
The targets with the 100us and 200us TC’s do not have time to decay. The worst one is the 200us that still has most of the eddy currents circulating at the time of TX switch off.
The very high rate of change of the TX current at switch off, induces new eddy currents in the targets, but roughly half of the eddy currents in the 200us target are used up to null the remaining eddy currents from the TX ramp.

[Orbit]

Drla baba lan da mi prodje dan ��Tema

[willybayot]

It is indeed clear from the simulation that the traditional PI looses a lot of the effectiveness of Eddy currents because of these inverted currents in the targets.
It is even more destructive if the pulse ON period is reduced (e.g. 50?sec instead of 100?sec). In that case, the xmit current has no flat top, it is just a saw tooth shape.

[Tinkerer]

Target Eddy current losses

It is indeed clear from the simulation that the traditional PI looses a lot of the effectiveness of Eddy currents because of these inverted currents in the targets.
It is even more destructive if the pulse ON period is reduced (e.g. 50?sec instead of 100?sec). In that case, the xmit current has no flat top, it is just a saw tooth shape.[ATTACH]57419[/ATTACH]

Indeed, only about 2.4mA of eddy current remain, of the about 18mA initially induced in the target, as we can see.

[Tinkerer]

Here is the SQUARE WAVE simulation.

[Tinkerer]

SQUAREWAVE CURRENT

Here is a look at the TX coil current, the blue square wave.
The green trace shows the eddy currents in the target.
The red and pink are the Flybacks.