Balanced VLF Tx

[Diya]

Free libraries for VLF Software?

Hallo,

A big Thank you for this great thread!

As a small contribution (maybe) to the software part of this project.
Mitov (http://www.mitov.com/demos) is offering a free version of their libraries fon non-comercial use
With this APIs it is possible to make the software without writing a single line of code! (see OpenWire Studio )
just drag & drop the components and wire them. please take a look at the demos and you will see what it could be done!

I hope the HW-gays(Aziz, Davor...) could make some complete version, witch Ivconic or others could trace it, so we can tray to devlope the software part, including:
filters, FFT, scopes, signal generators, spectrum.....

Regards
Diya

[Diya]

by the way, i think that the TX oscillator is similar to the Full Bridge Royer Oscillator used for Induction Heater or as a primary oscillator for tesla coil.
clever application in MD!

[Davor]

A Royer oscillator relies on the core saturation to perpetuate oscillation in relaxation way. So it is a bit different.
There is nothing too special about the bridge oscillators. They came en vogue in 90s as being better at phase noise issues than the rest of the solutions. Most of them are centre tapped, but a full bridge does not require a tap, so there you have it.

I'll see about Mitov thing, as the licensing is not completely clear to me. This program capabilities look a lot like some other software that runs on a very unaffordable side.

[Aziz]

Hallo,

A big Thank you for this great thread!

As a small contribution (maybe) to the software part of this project.
Mitov (http://www.mitov.com/demos) is offering a free version of their libraries fon non-comercial use
With this APIs it is possible to make the software without writing a single line of code! (see OpenWire Studio )
just drag & drop the components and wire them. please take a look at the demos and you will see what it could be done!

I hope the HW-gays(Aziz, Davor...) could make some complete version, witch Ivconic or others could trace it, so we can tray to devlope the software part, including:
filters, FFT, scopes, signal generators, spectrum.....

Regards
Diya

Hi Diya,

I'm going to publish another sound card detector controller (for Tablet/Netbook/Laptop PC operation and experimenting).
The infamous and brilliant "majik" choke will be used to make the alternating half sine coil current (bipolar half sine coil current).
(I can use my magnificiant center-tapped Tophat(c)(r)(tm) Coil further.)

It will be a simplified and KISS design of course. I haven't looked at the software link above yet (but downloaded big files for C-language support). Anyway, all you need is sound card driver interfaces and FFT. That would be enough.

The new detector controller will be published as soon as I have finished the prototype. Maybe in one or two (or three) month later. I'm quite busy these days.

Cheers,
Aziz

[Diya]

Hi Aziz,

All souncard IO, filtering and transformation stuffs are allredy implemented in this DLLs, you can use C++, VCL or even C# - my favorit- so the OpenWire Studio ist not needed at all, we can use for instance MS Visual Studio to do the final Standalone application.

I will be waiting for your new design

Best Regards,
Diya

[Aziz]

Hi Aziz,

All souncard IO, filtering and transformation stuffs are allredy implemented in this DLLs, you can use C++, VCL or even C# - my favorit- so the OpenWire Studio ist not needed at all, we can use for instance MS Visual Studio to do the final Standalone application.

I will be waiting for your new design

Best Regards,
Diya

That's fine!

The new controller design has two channel processing feature (stereo-output & stereo-input). The amplified RX (receive) coil signal and the TX (transmit) signal will be processed at the same time (for the advanced KillerApp(c)(r)(tm)).
Well, it requires a second USB sound card (two clock signals for triggering and defining the bipolar pulse timings). The internal sound card is destined to give the detection sound signal (beep).

I'll give my best to speed up the development now.

Cheers,
Aziz

[Diya]

Hallo Aziz,

Is a full duplex feature needed for your system?
I ask the quetion, because I was tracking your ideas & projects since long time! and in some of your first posts about soundcard solution, i think you mentioned that.

Could you please give me some specification about the required comercial HW? (usb soundcards)
just in order to make an overview about your new approach.

I appreciate the efforts you and EVRY member of this forum are doing to share your knowladge!

Regards,
Diya

[Aziz]

Hallo Aziz,

Is a full duplex feature needed for your system?
I ask the quetion, because I was tracking your ideas & projects since long time! and in some of your first posts about soundcard solution, i think you mentioned that.

Could you please give me some specification about the required comercial HW? (usb soundcards)
just in order to make an overview about your new approach.

I appreciate the efforts you and EVRY member of this forum are doing to share your knowladge!

Regards,
Diya

Hi Diya,

yep, a full duplex sound card is required. Best done with a 24 bit @96 kHz sample rate external USB sound card. I have recommended in the laptop metal detector thread two, where the black one is the best I have used so far.
(see this: http://www.soundcardsforpc.com/sound...ound-card.html )

Very cheap sound cards can't often be used as they don't obviously have a crystal clock reference source for both channels (input/output).

BTW, the latest metal detector controller (the oscillator version) in that thread can be used with only single (internal) sound card. One can make a nice Multi-frequency/VLF detector with it.

Cheers,
Aziz

[Diya]

Hi Aziz,
Thanks for the recomendations, I think you are focusing on the AK4396 + CS5361! very powerfull combination.
I have the SB X-FI SB0460 card (PCI version, but it s just fine to do some testing). I have also the second one witch is integrated in the motherboard.
I will tray to replicate your frontend controller as you pointed out, but may need some help.

The Sine & Cosine needed for Lock in Amplifier are the 2 internal clocks you mentioned before?

thanks in advence,
Diya

[Aziz]

Hi Aziz,
Thanks for the recomendations, I think you are focusing on the AK4396 + CS5361! very powerfull combination.
I have the SB X-FI SB0460 card (PCI version, but it s just fine to do some testing). I have also the second one witch is integrated in the motherboard.
I will tray to replicate your frontend controller as you pointed out, but may need some help.

The Sine & Cosine needed for Lock in Amplifier are the 2 internal clocks you mentioned before?

thanks in advence,
Diya

Hi Diya,

yes, the internal sine & cosine are needed for the Lock-in Amplifier to decode one frequency. If you have a dual frequency detector controller, you can use another Lock-in amplifier for that second frequency. But if you have a wideband response detector, it doesn't make sense to implement the Lock-in for all frequencies. A simple FFT would make it easily.

Best to implement a simple Lock-in detector in a loop-back operation to check, whether you have done it right: output -> input loop-back via cable connector. If you have done it right, the phase angle shouldn't change at all (shouldn't roll or drift). And you have done the software part right as well. And the sound card is appropriate for such an application too.

Aziz

[Diya]

Hi Aziz,
I got it Thanks

[Davor]

I have an update. For some time now I'm examining oscillators that turn from AB class to C class operation once they reach oscillation. I realised that if duty cycle is just below 50:50 split, some real magic happen. Results are reduced harmonics and reduced power consumption.

So this is my latest balanced oscillator. There are a few odd details aimed to retaining stability over larger power supply span and with a simple compensation adjust to accommodate for component tolerances and transistors gains. Most probably it could be refined, but I'm quite happy with it as it is. 5th harmonic is the largest one, but quite low. Transistors Q5 and Q6 are used as diodes, hence open collectors. Rdegen is a trimmer that acts as emitter degeneration between PNP and NPN transistors, so in effect it provides controllable negative feedback.

Next up will be some simple phase shifter for GEB and Disc purposes that uses balanced input.

[Thomas]

Is there a reason for the use of the transistors for diodes? I find that interesting.

[Davor]

Yes. The base-emitter PN barrier in transistors is doped more than regular diodes or base-collector, and thus have ~0.1V higher voltage drop. Reason for using this particular diode is that H-bridge transistors have near the same voltage drop and the whole contraption has decent operating conditions over much wider power supply voltages range. A transistor of the same family is a good match.

If you ever want a diode with a drop slightly lower than regular diodes, go for a JFET.

[Thomas]

Thanks, that's a nugget of Info I'll keep in mind.