TESORO GOLDEN SABRE

[simonbaker]

Hi,
I'm not sure your litz will be suitable there. If can't find enamelled copper wire there (I'll wonder if so... but could happen too) you can recover from some transformer or dc motor, dismantling it.

You need 30AWG wire: 0.25mm bare copper, with varnish around 0.27-0.28mm.

you can try with litz but results are undefined... as I know nobody made coils that way and litz is sometimes employed as shielding material...

You can also find the wire in old TV sets... and similar stuff... just recovering it. You could also use 0.30mm (bare wire) enamelled copper, if needed.

Kind regards,
Max

Is thicker wire like .30mm better for the TX coil, or is .25mm fine for both coils? We see different advice sometimes.

[wild_desert]

Thanks Amtech,Ivconic and Max
but Max:
you know Litz wire is better than single core wires. Because of low skin effect in high frequency. Say me if i'm wrong?

Another question:
Plain or concentrated coil?
What is your suggestion?
I guess plain coil has lower capacitive effect.

[simonbaker]

"..Thanks! That helps not waste money.R48, R49, R50, R51 - remove from circuit, they don't do anything?.."

Actually they dont..

Hi Ivconic -

If you get a chance, is it possible to make a TGSL PCB like this:

- Remove R48 - R51

- Make just tiny bit more compact so the PCB circuit fits inside a standard Compact Disk size (inside the circle). It almost fits now.

Maybe crazy idea, but I'd like to see if I can print directly on copper clad by putting PCB in Compact Disk tray of inkjet printer.

[ivconic]

Hi Ivconic -

If you get a chance, is it possible to make a TGSL PCB like this:

- Remove R48 - R51

- Make just tiny bit more compact so the PCB circuit fits inside a standard Compact Disk size (inside the circle). It almost fits now.

Maybe crazy idea, but I'd like to see if I can print directly on copper clad by putting PCB in Compact Disk tray of inkjet printer.

Ha,ha,ha,ha,ha,ha!!! You have more crazy ideas than me! Ha,ha,ha!!

Ok...call me crazy, but i will do that for you. Just give me some time, i cant do that right now...

[amtech2005]

TESORO GOLDEN SABRE

Wild_Desert , You can use Litz wire , but you need to use a smaller diameter or gauge of Litz . If Max said use 30 gauge of regular enamel , then use 33 gauge of litz . Yes , Litz is better !!!!! But your windings must be very precision windings on your forms. Minelab Commander series of search coils use Litz wire !!!!!!! Try to first wind the Lits wire to the DC resistance values on this chart. Then check your frequency of oscillation , if it is close to Golden Sabre 1265 light frequency . Then check your inductance , you will notice a difference from normal enamel wire !!!! And you will detect deeper than all of us using our cheap copper enamel.....Litz is much better wire , more expensive too , and $50. dollars for 500 feet .......Please let us know your results !!!!....See the chart I reposted again............Eugene

[Max]

Is thicker wire like .30mm better for the TX coil, or is .25mm fine for both coils? We see different advice sometimes.

Hi,
actual recipe is with 0.25mm at both tx and rx coils. you could use 0.30mm for tx with no pain, if needed.

On rx side wire is not so critical... you could use e.g. 0.27 or 0.28mm there too, and even more like 0.30mm if needed or you have just it.

The important is matching tx frequency and get a good non-resonant tuning for rx side, with phase required (around 200°) between tx and rx signals.

Kind regards,
Max

[Max]

Thanks Amtech,Ivconic and Max
but Max:
you know Litz wire is better than single core wires. Because of low skin effect in high frequency. Say me if i'm wrong?

Another question:
Plain or concentrated coil?
What is your suggestion?
I guess plain coil has lower capacitive effect.

Hi,
litz have important use in e.g. am radios... cause of that skin effect that make worse the Q of receiving coils made with monowire...

But in MDs is quite different: you have capacitance between wires to consider and have to match perfectly tx frequency for maximum parformance: that , you know, is possible with litz but usually problematic at few KHz range cause litz for AM is made of really thin stuff and you get large inductances with fewer turns than with enamelled copper wire.

So, it's possible using it, but you'll sure lose any reference e.g. about number of turns and need to find yourself.

"Concentrated" coils are the ones... the other way some manifacturer used for PI (e.g. in sandshark there's something like this... ) but they aren't good for VLF stuff... aren't effective cause you need large inductances of many mH and so need tight wounded turns.

Kind regards,
Max

[simonbaker]

Ha,ha,ha,ha,ha,ha!!! You have more crazy ideas than me! Ha,ha,ha!!

Ok...call me crazy, but i will do that for you. Just give me some time, i cant do that right now...

You're the best, take your time

(if too much trouble don't worry)

[simonbaker]

Hi,
actual recipe is with 0.25mm at both tx and rx coils. you could use 0.30mm for tx with no pain, if needed.

On rx side wire is not so critical... you could use e.g. 0.27 or 0.28mm there too, and even more like 0.30mm if needed or you have just it.

The important is matching tx frequency and get a good non-resonant tuning for rx side, with phase required (around 200°) between tx and rx signals.

Kind regards,
Max

What is meant by "non-resonant"? There is capacitor C6, which should be resonant with RX coil at about 16.3 Khz. Do you mean coil by itself should not self-resonate at 16 Khz?

[wild_desert]

Thanks Amtech
Thanks Max

I will test may coil and inform you.
I like to know it before make it. I'm not a "Copier Machine".

Best regards

[simonbaker]

LT1008 should be good replacement for LM308, therefore LT1012 should replace 2 of LM308 put togather in this schematic...noted as TL082....
I tested TL081 and later TL082 and those working erratic, producing to many "blah,blah..." in speaker when Sensitivity pot is over 50%.... Bad choice....
Also tested: 741,LM318,CA3130,CA3140,1458,4558,LM301,LM311,NE55 34.....
None of those can replace LM308 in this design!
Interesting was playing with CA3130; depth was much greater than with LM308....over 40%....but works erratically when no target in coil proximity???
It should be reconsidered, might CA....be used with some surrounding components changed...? I am to tired of experimenting, also have 8 Goldy pcb's to finish these days...so i let you, guys to check CA3134/40.....
Regards!

Hi, you posted this a while ago but I am interested...

What was the problem with each IC? Poor depth, stability? Can you say how much depth you lose chosing different ICs if used with your latest TGSL design?

[Max]

What is meant by "non-resonant"? There is capacitor C6, which should be resonant with RX coil at about 16.3 Khz. Do you mean coil by itself should not self-resonate at 16 Khz?

Hi,
I meant that RX tank must not be resonant with TX tank frequency. You have it a little displaced in resonant frequency from resonant frequency of tx tank. This means rx works out of tx resonance, in a way it's easy getting the signal but cutting some unwanted effects (expecially about stability) that show at TX-RX resonant designs.

Kind regards,
Max

[eclipse]

All OA in this design are old, low CMRR, high input noise, etc.
I also consider to experiment with different parts, thats why i just
ordered bunch of OPA's, LT's along with wima caps, precise resistors (10uV input noise). I wonder if there will be any improvement.
Cheers

[ivconic]

Hi, you posted this a while ago but I am interested...

What was the problem with each IC? Poor depth, stability? Can you say how much depth you lose chosing different ICs if used with your latest TGSL design?

Who's gonna remember all the wild things i ever tried with TGS!?!?!
I dont remember details at all.
I remember CA3130 worked so,so. NE5534 was very poor there. 741 worked "sharp" but weak...TL081 is only good replacement i have found so far.
I can not find LT's in local shops, so never tried.

[ivconic]

Hi,
I meant that RX tank must not be resonant with TX tank frequency. You have it a little displaced in resonant frequency from resonant frequency of tx tank. This means rx works out of tx resonance, in a way it's easy getting the signal but cutting some unwanted effects (expecially about stability) that show at TX-RX resonant designs.

Kind regards,
Max

Yup! Finally TX is 14.6kHz and RX 16.1kHz. TGSL TX LC is not parallel. There are 0.22 and 0.022 in emittor forming actually 20nF capacitance parallel to 6mH inductance..giving approx. 14.xxkHz.
I was seriously thinking to make ceneter tapped RX coil. Have expectations that it will give better performances..