Ideas to tinker

[Tinkerer]

It is clearly seen in the simulations that the response to the objectives is greater in the TEM method.
I wonder how samples are taken at the receiver, with a TX pulse that takes up the longest time in the transmission cycle.
I assume samples are taken during the TX pulse, perhaps similarly to the Tinkerer V1.

Probably the best way is if you post pictures of the simulation and then we look at what is happening step by step.

The circuit looks extremely simple, but it hides many secrets. The time has come to unveil the secrets.

[Jose]

It is clearly seen in the simulations that the response to the objectives is greater in the TEM method.
I wonder how samples are taken at the receiver, with a TX pulse that takes up the longest time in the transmission cycle.
I assume samples are taken during the TX pulse, perhaps similarly to the Tinkerer V1.

[Jose]

Thanks Tinkerer, I'm done downloading LTspice. I'm watching the simulations, trying to learn

[Tinkerer]

Right.

I put the 2 simulations together to make it easier to compare.
Look at the target response and compare the power consumption. for the target response click on the inductors of the targets. This shows the eddy currents in the target, related to what the RX coil will see.

I made the Flyback and the peak TX current roughly the same level. Try changing each of the parameters at the time.

[Jose]

I am trying to understand the TEM method.
The second TX transmission pulse starts right at the end of the high voltage pulse, so it does not oscillate.
Unlike the traditional system, (and by way of comparison), the TX pulse is usually 10% of the duty cycle. In the TEM method, the transmission pulse is 90% of the duty cycle.
It is right?

[Tinkerer]

Traditional PI compare TINKERER_TEM

I was thinking to act like a PI Tx current needs to be constant(not changing). Tx current your reply#4 looks like a saw tooth. Is my thinking wrong?

attached is a simulation, comparing Tinkerer_TEM with traditional PI

[Tinkerer]

Getting interesting

[eclipse]

just figured why not do this - we could have both (multi-frequency) type deal (half sine + half truncated sine)

maybe focus on processing more .. rx/preamp sampling etc.

[eclipse]

Bipolar TSW with the bipolar schematic posted above after playing some of the values

[eclipse]

Here's an experimental circuit. What do you think ?



experiment.zip


And the bipolar circuit.
It can be made to become the THS.
Can it be made to be TEM ?

[eclipse]

Here's the bipolar version with dual TX wire coil & 2 mosfets.
Note the lower coupling factor of TX/TX2. It's not tested in real life.

TEM_0.3.zip

[6666]

Ideas on how to modify this to become a bipolar TX?
I've made it with a simulation but it requires bifilar TX coil wire and another transistor - the coil wire requirement is a bit constraining.
H-bridge solution didn't seems to work (on a working h-bridge circuit I swapped the damping resistor with capacitor and result was ringing all over the place).
I can post these 2 circuit if it would help.

Could you post them please.

[eclipse]

Ideas on how to modify this to become a bipolar TX?
I've made it with a simulation but it requires bifilar TX coil wire and another transistor - the coil wire requirement is a bit constraining.
H-bridge solution didn't seems to work (on a working h-bridge circuit I swapped the damping resistor with capacitor and result was ringing all over the place).
I can post these 2 circuit if it would help.

[Tinkerer]

I was thinking to act like a PI Tx current needs to be constant(not changing). Tx current your reply#4 looks like a saw tooth. Is my thinking wrong?

thank you for your input.

What we traditionally call a TX pulse in PI, is about similar to a sawtooth. When we pulse the PI ending with a constant current, we call it Flattop PI pulse. Most of the denominations we use are just common use, there are no exact rules that I know of.

After the TX pulse we have a "listening period" where we traditionally like the coil current to be 0.

With the circuit above, being a hybrid, it is never a 100% PI nor a 100% VLF. It is always a bit of both. The good thing is that we can change it to be more of the one, or the other.

I used to call one variation I used as 2 TAU, ie. a fast ramp and a slow ramp. The excitation of the targets being more ideal for short TC targets and long TC targets respectively.

The Tinkerer TEM_02 simulation shows a mostly PI response to the target.

[green]

This is basically a flexible PI-VLF hybrid.

You can demodulate like a PI
You can demodulate like a VLF
You can demodulate like a PI and a VLF at the same time

You can also make the circuit behave more like a PI or more like a VLF.

There are many, many ways to change and adapt this basic circuit to the various uses of detectors.

My choice of Instrumentation Amplifier was just a lazy choice to find something to fit your circuit, because I could not remember how to make the LTSpice see the THAT that you used.

I was thinking to act like a PI Tx current needs to be constant(not changing). Tx current your reply#4 looks like a saw tooth. Is my thinking wrong?