TESORO GOLDEN SABRE

[Fred]

Hi Qiaozhi,

I think Max said that he could confirm there was a phase-shift to the left with a Tesoro factory-made concentric coil, but do not remember what he found with the DD..

I made my DD coils with a left shift.The problem was to be able to get the right angle with a minimum residiual voltage.
Also an amplitude variation dependent of metal implies that the coils are not perfectly nulled,or else all metals would make amplitude to rise.I think this means o good coil with good discrimination is NOT a perfectly nulled coil.

For the concentric coil, a left-phase shift means that the target is detected as it enters the RX coil, whereas a right phase-shift will only detect the target as it leaves the RX coil, which makes it more difficult to pinpoint amongst the trash..

That´s interesting,small detail tha make the difference.
The experience i have with CC coils is not good, as i had to make too many nulling turns , thus ruining the detection range.
Omega coil worked well, but it was a coil i made for other detector and i never tested phase shift or nulling with the TGS.

Regards,
Fred.

[nelson]

Hi Qiaozhi. Yes you are rigth, i missed that reply.
Sorry, and thanks
Take care
Nelson

I guess you missed my previous reply to this question:
http://thunting.com/geotech/forums/s...postcount=2273

[Qiaozhi]

Hi Qiaozhi,

I made my DD coils with a left shift.The problem was to be able to get the right angle with a minimum residiual voltage.

Interesting... I'll do some more checks, probably sometime next week. The DD coil I made had some relatively thick wire (0.56mm), and this does it make it more difficult to null. Perhaps using thinner wire would make it easier to find a point where the phase-shift is to the left.

Also an amplitude variation dependent of metal implies that the coils are not perfectly nulled,or else all metals would make amplitude to rise.I think this means o good coil with good discrimination is NOT a perfectly nulled coil.

That's true. I have stated previously that Tesoro coils are not perfectly nulled. Usually there is around 15mV residual across the RX coil.

That´s interesting,small detail tha make the difference.
The experience i have with CC coils is not good, as i had to make too many nulling turns , thus ruining the detection range.
Omega coil worked well, but it was a coil i made for other detector and i never tested phase shift or nulling with the TGS.

Regards,
Fred.

That's another experiment for us to try.

[tiktak]

Hi,

HI,
Thanks to all folks for advices.
I will try to check all the moments you have point me.

1.ICs are fitted with socets!I think that this is not the probleme because I use same way on my first device!

2.I draw my PCBs on hand and they are not 100% the same.This could be the reason.But my first device PCB is hand drawn too.But they are the same.

I will check all again and will post here.

[tiktak]

Hi

HI,
Also my TX frequency is 28,5 kHZ for both devices.
How can I reach 14 kHz buy adding or taking off some windings?
Max please look the numbers from my previous post and tell me are this the numbers for 255 DD.
Thanks.
I use 100 w 0,25mm wire.
Thanks

[WM6]

HI,
Also my TX frequency is 28,5 kHZ for both devices.
How can I reach 14 kHz by adding or taking off some windings?

By adding between 3/5 - 4/5 existing windings, if your measurement was correct and you measure basis frequency and not only some parasite frequency.

[ivconic]

Might be the frequency 14.25kHz, only you measured second harmonic?
If you respected datas i posted earlier (255x137 and wire 0.25...107w and 102w...or simillar) than it is almost impossible to achieve 28.5kHz frequency! Impossible!
Which type of frequencymeter you are using?
To many open questions at your work and posts Tiktak.... Many times i didnt wanted to involve myself in some more detailed discussion here cose there is some basic knowledge and skill you MUST have before attempt to make any of present devices. Not to mention TGS, which is rather complex to build, and it is not most suitable for a beginner as starting project. Although schematic looks simple, although coil also looks easy to made....it is not the case for sure. TGS with coil, presented here is very difficult to make properly.Not for beginers at all. Anyone can draw pcb,solder components and make some coil....but it will not work! Trust me.
Do not understand me wrong here. I am just saying what is real situation, facts.
Zillion of question, always same question,always same problems with this TGS.
This thread tends to be hugest thread on internet ever!
To make TGS right and properly, you must undestand its working principles first.
Also, many of you - you must return back to very first pages and carefully read all posts. Everything is already elaborated pretty detailed here, step by step.
Very Best Regards!

[Qiaozhi]

Might be the frequency 14.25kHz, only you measured second harmonic?
If you respected datas i posted earlier (255x137 and wire 0.25...107w and 102w...or simillar) than it is almost impossible to achieve 28.5kHz frequency! Impossible!
Which type of frequencymeter you are using?
To many open questions at your work and posts Tiktak.... Many times i didnt wanted to involve myself in some more detailed discussion here cose there is some basic knowledge and skill you MUST have before attempt to make any of present devices. Not to mention TGS, which is rather complex to build, and it is not most suitable for a beginner as starting project. Although schematic looks simple, although coil also looks easy to made....it is not the case for sure. TGS with coil, presented here is very difficult to make properly.Not for beginers at all. Anyone can draw pcb,solder components and make some coil....but it will not work! Trust me.
Do not understand me wrong here. I am just saying what is real situation, facts.
Zillion of question, always same question,always same problems with this TGS.
This thread tends to be hugest thread on internet ever!
To make TGS right and properly, you must undestand its working principles first.
Also, many of you - you must return back to very first pages and carefully read all posts. Everything is already elaborated pretty detailed here, step by step.
Very Best Regards!

Hi Ivconic,
I agree.
This project is not one that should be attempted lightly. There are mainy gotchas along the way that will inevitably lead to huge frustration, both for the person building the detector, and for the other forum members.

tiktak - The TX frequency you have determined is probably a measurement error. As Ivconic has noted, this is the second harmonic, which looks suspicious. Have a look at the TX waveform with a scope and directly measure the period from there.
If your comparators are in sockets, then that's most likely the cause of the instability, regardless of whether you claim to have had this working previously. It is bad practice to use sockets for comparators if the input signal hovers around the switching level, especially when there's no hysteresis. Do you have access to an oscilloscope? If not, then you will probably never be able to really fix this problem.

[WM6]

Additionally to tictac:

As ivconic say there is practically impossible to get double basis frequency if you consider here suggested data. If you consider all suggested data, you can measure 28kHz only by wrong procedure (e.g. f-meter input can be overloaded by wrong connection, mean, your TGS can be entirely ok and parasitic mirror frequency can arise in input stage of f-meter, which can be in different way coupled during measurement on MD output).

Only in case that your coil dimensions (diameter) are smaller than suggested, you can solve problem by adding some windings as previous noted.

[tiktak]

Hi,

Hi,
Thanks all folks.

WM6.Yes maybe you are right.And I think my coil is ok.

Qiaozhi No man I dont have scope.I am planing to buy one soon.But never used one.You will have to help me here.Can I find good 2-chanel scope for around 200 euros?Belive it or not my first TGS is beast.I never have solder any PCB before!But wanned it so much and with help from MAX,IVCONIC and others I made it.Dont now whats the probleme here but I will find it soon.
Now when I think I have a friend with scope!For what should I look.

IVICA.
First I have send you photos of some of my finds.Did you check them?
Basic YES.Not enough YES.But LEARNING IVCONIC,LEARNING...........
Thats why we are here.
I measure with cheap multimeter.DT9208.
I touch TX exit from PCB.

THANKS

[Max]

HI,
Also my TX frequency is 28,5 kHZ for both devices.
How can I reach 14 kHz buy adding or taking off some windings?
Max please look the numbers from my previous post and tell me are this the numbers for 255 DD.
Thanks.
I use 100 w 0,25mm wire.
Thanks

Hi,
as previously noted your reading of frequency is sure wrong: second harmonic

Probably you have 14.25Khz but your meter cannot read it cause of e.g. bad sens at lower frequency (that's a bit suspicius cause often the lowest sens is at higher freq... but probably signal is distorted too).

Where did you measure frequency ? Which point ?

If you used collector of osc transistor you will read the frequency right way I think cause there are many volts there... if instead you read it at output of rx preamp (note that frequency is the same of TX cause it's air-core transformer) you could have troubles with low quality frequency-meter.

Try to read at collector of transistor... just there coil is connected to osc part on pcb: you will read it good if not distorted much.

If , in case you read at preamp good on previous detector, and now you read it bad... look : it could depend on nulling... more severe nulling to zero means less voltage peak to peak at output of preamp... thus resulting in unreadable or wrong reading on low quality frequency-meter.

Good numbers are 100 for tx and 105 for rx coil, wire 30awg (0.25mm bare wire).

I will look also at line regulation for 8 volts there: if you notice lower voltage try to investigate if there's something that need too much current and become hot there or if your supply goes down on voltage / protection cause of hi current absorbtion: notice also that some kind of speakers make it goes (when all ok) well over 150mA consumption when sound; on no sound you will get something about 30-45mA depending on stuff you use as components.

Kind regards,
Max

[ivconic]

Hi,
as previously noted your reading of frequency is sure wrong: second harmonic

Probably you have 14.25Khz but your meter cannot read it cause of e.g. bad sens at lower frequency (that's a bit suspicius cause often the lowest sens is at higher freq... but probably signal is distorted too).

Where did you measure frequency ? Which point ?

If you used collector of osc transistor you will read the frequency right way I think cause there are many volts there... if instead you read it at output of rx preamp (note that frequency is the same of TX cause it's air-core transformer) you could have troubles with low quality frequency-meter.

Try to read at collector of transistor... just there coil is connected to osc part on pcb: you will read it good if not distorted much.

If , in case you read at preamp good on previous detector, and now you read it bad... look : it could depend on nulling... more severe nulling to zero means less voltage peak to peak at output of preamp... thus resulting in unreadable or wrong reading on low quality frequency-meter.

Good numbers are 100 for tx and 105 for rx coil, wire 30awg (0.25mm bare wire).

I will look also at line regulation for 8 volts there: if you notice lower voltage try to investigate if there's something that need too much current and become hot there or if your supply goes down on voltage / protection cause of hi current absorbtion: notice also that some kind of speakers make it goes (when all ok) well over 150mA consumption when sound; on no sound you will get something about 30-45mA depending on stuff you use as components.

Kind regards,
Max

Uh! I think that is way to much consumption!
With ordinary 8 ohms speaker /0.25W, my devices drains 25-30mA without sound and approx. 60mA with loud sound (full detection)....
Funny...same drains i measured yesterday on old&rusty Micronta 4003!
Regards Max!


P.S.
Yup! 105 and 100 and 107 and 102 are best numbers so far.....0.25mm/255x137

[tiktak]

Hi,

Hi,
Ok.
So its mistake?
I remember that we discus the price of some good 2 chanel osciloscopes here?What were the number?

Max which transistor did you mean?2N2222 or 2N2907?
Because you told me to try measure from TX lead.
I now that my multimeter is too cheap for this.

Have to go now will see you soon.

Thanks

[Qiaozhi]

Qiaozhi No man I dont have scope.I am planing to buy one soon.But never used one.You will have to help me here.Can I find good 2-chanel scope for around 200 euros?

Have a look on ebay for a 2-channel oscillscope with at least 20MHz bandwidth. You should be able to find one for around 200 euros.

[Max]

Hi,
Ok.
So its mistake?
I remember that we discus the price of some good 2 chanel osciloscopes here?What were the number?

Max which transistor did you mean?2N2222 or 2N2907?
Because you told me to try measure from TX lead.
I now that my multimeter is too cheap for this.

Have to go now will see you soon.

Thanks

Hi,
I meant test-point #1 , collector of PNP transistor at oscillator.

Look at picture.

Kind regards,
Max