DEEPER PI DETECTION DEPTH

[Davor]

Hi Tinkerer,

Yeah, spice gets confused when same inductances appear twice in two K statements, but it is usually due to some mistake on our own side. I'll check your circuit tomorrow, now I'll hit the hay.

[Davor]

I'm glad you like it, so do I! We call this "truncated half-sine." Yes, it really works.

So you ARE impersonating Whites here. Good to know - I'm still a rookie here. Please pay John my respects, I like what he does.

[Carl-NC]

So you ARE impersonating Whites here. Good to know - I'm still a rookie here. Please pay John my respects, I like what he does.

Yup, I work for White's... no secret. It was agreed when I joined White's that I could continue running Geotech with no interference. Ergo the neutral nature of the forums.

John just left my office. He's a clever engineer, and an interesting person.

[Davor]

Left for coffee or left for good? The former would be much better for Whites.

[Aziz]

Left for coffee or left for good? The former would be much better for Whites.

I was wondering about the fact, that the mentioned hybrid patent is registered under his own name. No White's mentioned there.

Maybe Carl can say more about this. Carl?

Aziz

[Aziz]

Here is a concrete proposal for TX parameters, that can be switched for a large coil of 1 meter diameter and a smaller coil of 0.5m diameter. It is the best I can come up with.

If you find something better, I would like to try it.
...

Tinkerer,

the TEM transmitter is the best, versatile, cheapest and simplest TX transmitter. It is even better than the half-sine current type. Trust me.
(And it's prior art. No one can patent it. )

You can energize it with high voltage as well (100 V) in conjuction with higher PPS rate. But you shouldn't let saturate the coil current (t-on << TC of TX) as it gets energy inefficient.


Aziz

[Tinkerer]

Tinkerer,

the TEM transmitter is the best, versatile, cheapest and simplest TX transmitter. It is even better than the half-sine current type. Trust me.
(And it's prior art. No one can patent it. )

You can energize it with high voltage as well (100 V) in conjuction with higher PPS rate. But you shouldn't let saturate the coil current (t-on << TC of TX) as it gets energy inefficient.


Aziz

I agree, TEM is the best. The Truncated half sine gives some advantage for targets of very short TC, but gives less signal response for the same power consumption.

There is a modality using an IGBT instead of a Mosfet, that gives quite different results. I have not fully investigated that.

Tinkerer

[Carl-NC]

I was wondering about the fact, that the mentioned hybrid patent is registered under his own name. No White's mentioned there.

Maybe Carl can say more about this. Carl?

Aziz

Like all patents, it lists the "inventor" (John Earle) and the "assignee" (White's Electronics).

[Aziz]

Like all patents, it lists the "inventor" (John Earle) and the "assignee" (White's Electronics).

Great!
I hope, we will see it's successful implementation and (cheap) commercialisation.
Another big and greedy metal detector company needs a small knock-out (competition).

Aziz

[Davor]

So it seem John left White's. Hopefully for something even better.

[Carl-NC]

So it seem John left White's. Hopefully for something even better.

I doubt it, he just left my office again. Hopefully for something even better.

[Carl-NC]

OK, I'm lost in my own damned forums... can someone point me to the original thread on the TEM dev?

[simonbaker]

OK, I'm lost in my own damned forums... can someone point me to the original thread on the TEM dev?

I'm looking too... is this it?

http://www.geotech1.com/forums/showp...&postcount=819

[Aziz]

I'm looking too... is this it?

http://www.geotech1.com/forums/showp...&postcount=819

I'm lost too! Good find.

It is based on this principle:
http://www.zonge.com/PDF_Papers/TEMposterAs.pdf

Aziz

[Aziz]

Ok guys,

found another TEM source. In this thread (post #51):
http://www.geotech1.com/forums/showp...3&postcount=51

Look at TEM1 and TEM2 variants.

Aziz