TESORO GOLDEN SABRE

[salim]

hi im starting TESORO GOLDEN SABRE project but in my country i have this kind of lm308



can i use it instead the other component can some one help me to adapt it to typon


thanks

[Max]

Hi Max, Ivconic,

Max, thank you for this clear explanation of your Mono stable mod connections!

Guys, would you check this coil setup? This will be my next coil with dimensions recommended by Ivconic. Is there any recommendation for the direction of coiling of both TX and RX coils?

Thank you guys!

Hi,
seems close to what's needed. Number of turns is not an absolute param cause we all use slightly different formers and wire... but yes, really close for sure. Exact numbers depends on e.g. frequency you have to match for tx.

About direction of winding... not much important, important is how you wire coil at the end, I mean you must respect correct phase shift or disc will not work good.

Usually people wind coils always same way (e.g. always clockwise or counter-clockwise) depending on their feelings about (some feels better winding one way than the other... others just don't care much), what's important is right shaping and tuning, including frequency matching, nulling and phase shift.

As example... I wind coils always clockwise, then tune after the coils, wirings etc... that's cause I use left hand to hold former (wood made with nails) and right hand to wind the coils. I feel that way comfortable for that coils.

Kind regards,
Max

[Aiko]

Hi Max, Ivconic,

Max, thank you for this clear explanation of your Mono stable mod connections!

Guys, would you check this coil setup? This will be my next coil with dimensions recommended by Ivconic. Is there any recommendation for the direction of coiling of both TX and RX coils?

Thank you guys!

[Max]

Can't find the schematic on paper!

Then I made these... for use with that PCB design you find in attachment.

1. is how to connect for normal/original audio of TGS (proportional)
2. is how to connect (fixed) monostable audio
3. is how to select by switch between monostable and original audio

Kind regards,
Max

[Max]

Hi Max,

I think that your TGS mod is very interesting and I want to try to make it. If you have a time I will be very grateful if you show us how to switch between Mono stable and without Mono stable. I want to choose between these two conditions with a switch.

Thank you in advance!

Hi,
it's really easy... a switch is all that's needed. I made in my last TGSL using that pcb... the one by Ivconic but with other options including transistor audio (always by Ivconic) and monostable.

Indeed, I've mounted monostable also on my first TGS (that uses the first pcb design)... always enabling monostable or disabling by a switch.

I think Ivconic posted also wiring about that in some older page but now I'm not sure about.

I made a small schematic on paper when first used it... but can't find it now.

Will look for it.

Kind regards,
Max

[Aiko]

A little demonstration of my TGSL. The discrimination is excellent, but the detections distance is still not so good – about 18-20 cm for 20 euro cents.

http://www.youtube.com/watch?v=4dhhuXAthOI

[Aiko]

Hi Max,

I think that your TGS mod is very interesting and I want to try to make it. If you have a time I will be very grateful if you show us how to switch between Mono stable and without Mono stable. I want to choose between these two conditions with a switch.

Thank you in advance!

[Aiko]

I was missing to connect the RX end to the ground in the search head. So I connect it now as is in Icvonic’s cable setup and wow +5 centimeters in the detection with my first coil and my improvised cable

[simonbaker]

Hello simonbaker,

Your proposal is tested. Thank you!

15n is best value for now, but I can not try lower values of this capacitor because I do not have smaller then 15n capacitors. I have only 15 n and 1n. With 16n the difference is small and with 17n and 18n are unstable.

Regards!

Thanks for giving results. I am also working on completing the same circuit and trying these same ideas.

Lower capacitors than 15n will probably not increase sensitivity anyway, just make it less, so I wouldn't bother trying.

Remember that you must take MD outdoors away from power lines to test properly -- it is normal that a sensitive detector may chatter inside a house with all the wiring, etc.

-SB

[ivconic]

You also not need to "hunt" exact frequency. It can work just fine with frequencies from 13kHz up to 16kHz. In the past i also made one pretty funny coil which gave 12.1kHz with TGS setup and it worked just fine with very good depths. Later, working more and more i established (for my needs) exact number of turns and exact wire with wich i usually gain 14.1 to 14.6kHz.... Personally i dont mind and dont bug myself much with exact frequency. So...just try to respect proper inductances (6mH and 6.5mH) and dont worry.

[Aiko]

Hello simonbaker,

Your proposal is tested. Thank you!

15n is best value for now, but I can not try lower values of this capacitor because I do not have smaller then 15n capacitors. I have only 15 n and 1n. With 16n the difference is small and with 17n and 18n are unstable.

Regards!

[simonbaker]

Simon,

1) Yes, Frequency for Tx is correct. ~13.98KHz

2) 8" Concentric coil (open centre)

Tx = 23.04 ohms, 5.43mH, Q 1.48
Rx = 23.37 ohms, 6.36mH, Q 1.71

3) Yes, .015 uF (15nF)

Hope this helps,

Molzar

Thank you very much, I'm interested in original phase information.

13.98 kHz is strange, but explained if .022 uF cap in oscillator is actually .0253 uF (15% high) according to my simulations.

Regards

-SB

[Molzar]

Hi Molzar:

1. Were you ever able to remeasure the TX frequency of your Tesoro TGS? Your first measurement was 13.985, but you had question about meter.

2. Can you measure the resistance and inductance of the 8" coil RX and TX coils?

3. Can you confirm that the RX capacitor is 15 nF on the actual PCB?

I would greatly appreciate it.

Regards,

-SB

Simon,

1) Yes, Frequency for Tx is correct. ~13.98KHz

2) 8" Concentric coil (open centre)

Tx = 23.04 ohms, 5.43mH, Q 1.48
Rx = 23.37 ohms, 6.36mH, Q 1.71

3) Yes, .015 uF (15nF)

Hope this helps,

Molzar

[simonbaker]

Of course simonbaker .

The voltage is positive – 75 mV for C12 and 40 mV for C15.

The frequency, if my multymeter measures properly is 13.6 kHz. Unfortunately I can not measure the inductance with my multymeter.

Resistance on RX is 19.3 ohms and for TX is 17.7 ohms.

Regards!

(Damn, lost the message, starting over)

Here is a possible small tuning your could try, no guarantees.

I will make some guesses based on your measurements. I hope others will check and correct any mistakes, so don't try this for a while.

Based on your oscillator freq of 13.6 kHz, I am guessing your TX coil is 6.5 kHz (by playing with LTSpice).

Based on coil resistances, I am guessing your RX coil is (19.3 / 17.7)**2 * 6.5 = 7.7 mH. (I hope others can check and correct that).

Based on RX inductance and assuming RX capacitor C6 is .015 uF, your RX resonant frequency is about 14.8 kHz.

You may be able to pick up about 8 dB gain (hardly much, but hey) by lowering your resonant frequency a little, but not so much to cause a phase shift that would mess up your discrimination. My calculations with LTSpice show that 14.0 kHz would be a reasonable choice.

If you change the RX capacitor C6 to .017 uF that should come close. Ivconic left space to add a capacitor to PCB, so you could add .002 uF there. But be careful, a little too much capacitance will start shifting your discrimination knob settings, so measure your original .015 uF cap as closely as possible and any cap you add.

Anyway, something to fool around with.

Cheers,

-SB

[Aiko]

Of course simonbaker .

The voltage is positive – 75 mV for C12 and 40 mV for C15.

The frequency, if my multymeter measures properly is 13.6 kHz. Unfortunately I can not measure the inductance with my multymeter.

Resistance on RX is 19.3 ohms and for TX is 17.7 ohms.

Regards!