Question about tgsl

[dbanner]

You may also consider adding some turns to your Tx coil to bump up the inductance to closer to the prescribed inductance.
A factory made tesoro concentric is always the best, but a home made always requires tinkering because of so many variables involved with the feed back coil and balancing, it is not so easy. Change the feedback turns, you change the Tx frequency, so it's a give and take scenario.

[waleed]

Thanks dbanner for the useful informations...but it's really not easy to get everything right,idk which to change it's the cops or adding some extra turns to the coils,adding or subtracting a turns to the bucking coil will change the frequency of tx,idk actually.
Maybe I'll build the DD coil seems easier to do and nulling even though I like the concentric more :/, can someone with experience make it for me with enclosure? I'll pay for him.

[dbanner]

An alternative which I never really explored but which I know works well is to introduce a feedback network of trimmers for voltage(nulling) and phase. Have a look at the nautilus feedback network. So instead of fiddling around with feedback (bucking) turns, you simply adjust trimmer pots.
One 100K trimmer nulls the Rx coil, the other 100K trimmer adjusts the phasing, so by playing with the two, you can set the concentric coil to your desired parameters. You might want to try it, if only for experiment, you can only learn more knowledge. You can use the same values as in the schematic, as the nautilus coil is almost the same as the tesoro.

[dbanner]

With this method, all you have to do is set the correct Rx and Tx resonant frequencies, the trimmers do the rest so long as your feedback coil is within the trimmer range for nulling. (sufficiently close to null, the trimmer will fine tune the final nulling) You can make up this circuit on a small pcb which fits inside the coil housing. Many proprietry coils have similar circuits inside the housing.
Fiddling around with small loop of wire I expect is no longer required.

[waleed]

This method seems to be good to use. I'll try it. I would ask should I ground the end wire of Rx (the one going to the non inverting) to the board gnd?

[dbanner]

That's a good question. Yes, the side connected to the non-inverting input is connected to ground on the board(battery negative). You can have a look at the Golden sabre schematic or any old tesoro schematic, they all show this end of the Rx coil is grounded.
There is plenty of discussion on another thread about falsing on wet grass with grounded Rx. I think it was said that the Rx should be left floating. You can try it both ways. In the original Tesoro units, the Rx coil is grounded at the connector internal to the main box.
My home built TGSL is with DD coil and I left the Rx ungrounded, it works excellent, no falsing on wet grass, so I left it ungrounded.
The original tesoro concentric Rx coils are tiny compared to 0.5/Tx diameter of the self made. So maybe that has something to do with it. Not sure.

[waltr]

I also did not ground the RX coil. Works great without falsing on wet grass.
In evaluating the design I see no reason to ground the Differential RX in.

I need to play with that Nautilus circuit. I have the question of why connect the RX coil to ground and will this circuit still work without that ground connection. Have a lot of other circuits to work on so won't be getting to this one soon.

[waleed]

I have found in my store a new spool of 0.85mm sized wire, it is ok to use it for building a coil?
If so,how many turns I need for tx and rx and bx?, I'll build the 10" concentric coil, I'm using the coil calculator and i thing i have no problem with Rx coil, but the problem is how many turns I need for Tx and Bx (feedback coil)?, I know that bucking coil turns depending on the number of turns for both tx and rx not only the area diameter, so in my case number of turns would change because of the size of the wire (0.85mm). So how many turns I need for Tx and Bx for that sized wire and 10" coil?

[waltr]

How you read this:
https://www.geotech1.com/cgi-bin/pag...anar/index.dat

[kt315]

there is NOT a manual how-to-balance-coil, NOT EXISTS, just manuals how-to-make. you have to do balance yourself connecting your mind.
the forum has not possibility to keep a staff of professional consultants helping to everybody in coil bulding. no finance, we are just money-free
peacemakers.

[waleed]

How you read this:
https://www.geotech1.com/cgi-bin/pag...anar/index.dat

Yea I read that,but it still not enough clear because Bx turns not only depend on the area enclosed for both TX and RX but also on the number of turns,anyway I'll figure out how to do that for my 0.85mm wire np.

there is NOT a manual how-to-balance-coil, NOT EXISTS, just manuals how-to-make. you have to do balance yourself connecting your mind.
the forum has not possibility to keep a staff of professional consultants helping to everybody in coil bulding. no finance, we are just money-free
peacemakers.

xD I always like your comments even though they are tough sometimes but actually it's the truth ��

[kt315]

try to learn my pics done much years ago.

[waltr]

Yea I read that,but it still not enough clear because Bx turns not only depend on the area enclosed for both TX and RX but also on the number of turns,anyway I'll figure out how to do that for my 0.85mm wire np.

xD I always like your comments even though they are tough sometimes but actually it's the truth ��

That article is about all we can tell you without actually have made to specific coil ourselves.

20ga (0.8mm) wire sounds a bit large for the TGSL. The resistance will be lower.
If you read the TGSL threads (hundreds of pages) some one tried thicker wire, thinking higher current = more distance, and the TGSL did not work correctly.

Best if first time building is copy what has been proven to work. Then experiment with mods, etc.

[waleed]

try to learn my pics done much years ago.

Thanks for sharing,but what would I achieve by doing this circuit?, it look to me that you can adjust the resonance and the resistance of the wire right?

That article is about all we can tell you without actually have made to specific coil ourselves.

20ga (0.8mm) wire sounds a bit large for the TGSL. The resistance will be lower.
If you read the TGSL threads (hundreds of pages) some one tried thicker wire, thinking higher current = more distance, and the TGSL did not work correctly.

Best if first time building is copy what has been proven to work. Then experiment with mods, etc.

Yea you are completely right,but I think that I can put a resistor series to the coil to fit the rage of 18-25 ohm maybe

[dbanner]

Read this article, it will certainly add to your knowledge.
Generally speaking, use thicker wire for Tx and thinner wire for Rx. The wire gauges for the Tx and Rx do matter, and not just because of resistance, but these IB concentric coils have a lot of design parameters that are not quite transparent to the new players. Like Q factor and coupling efficiency (tranformer action), temperature stability ( sensitivity in the linear region using 25 degrees C as a baseline) and ground effects in relation to the size and geometry of the coil. There is no getting around this, so follow the advice of george payne and use his guidelines as a reference when making these concentric type coils.
As for the feeback coil, I recommend using a double spool as Cscope has done with their concentric coils. This makes it very easy to add/remove turns on the fly, to bring the Rx into balance(null). Remember its about cancelling the Tx that the Rx coil sees. Overwind the buck, then just keep removing turns until you cancel the Tx field. Then you can reconcile the Tx frequency by capacitance. The double spool gives the buck coil its own groove, so the Rx stays in place and is not disturbed.