TESORO GOLDEN SABRE

[simonbaker]

No they isn't measurements from this LF353 pin 7?

the measurements I take him from COIL RX.
That is to say disconnect COIL RX from the detector and I connect the oscillograph in the coil RX and read the measurements in the oscillograph.

f=17.0000KHz They is measurement in the oscillograph. I be believed frequency that it is.

Regards,

Well -- oscilloscope frequency should be same as TX frequency for null signal -- what happened?

Voltage of RX null signal seems too high in my opinion. Do you have a shield.

Have you finished the TGSL? Does it work? How well?

You will need to provide many details for any more help from forum I think. Photos of coil, PCB, oscilloscope signals, etc.

Cheers,

-SB

[fmnotes]

Well -- oscilloscope frequency should be same as TX frequency for null signal -- what happened?

Voltage of RX null signal seems too high in my opinion. Do you have a shield.

Have you finished the TGSL? Does it work? How well?

You will need to provide many details for any more help from forum I think. Photos of coil, PCB, oscilloscope signals, etc.

Cheers,

-SB

HELLO.
I thank you despite very that you want me to help.
tgsl I have finished him,
other I am not satisfied from the distance that detects the metals,
it is not big the distance,
that is to say one Euro in the 8 cm.
I believe that it is small the distance.
problem with the segregation of metals,


I will request you if you can,
say to me what to check.
i I will photograph the inductor and tgsl and the clues of oscillograph.

regards

[habitbraker]

A good frame to support your plastic sheets surely makes things easier. I have been getting my sheets from "widgetworks" http://www.widgetworksunlimited.com/...-black-060.htm

I have found that the correct time/temp combination is 400 degrees for 2 minutes, and that is starting with a preheated oven. I just use an ordinary shop vac. but, I typically have to "work" the plastic into sharp corners and between the ears with some sort of tool while still soft. Generally they come out very good.

Now, to keep this relavent to the TGSL thread, here is my latest 20cm coil.. 31 cm for a Euro using Eduardo's new PCB. My standard 255mm coils get a euro at 36cm but that advantage is drastically reduced in the ground. Detection depths are about the same for both in the ground..


Top pic is my standard 255mm coils, bottom pic is my latest 200mm coil..
This one has epoxy filled ears, 2 part marine foam in the middle and a layer of potting epoxy on the bottom. Very light and rigid!

Thanks, Dfbowers, for the answer.

I guess I need to make 20cm coil too because that would fit in my oven (using right frame). What is count of turns for this diameter? Im using hamburger method too.

Looking at your beautiful coils gives me dose of inspiration

My Eduardos PCB still waiting for some parts. Q: What about using 7809 instead of 08?
Anyway, I will try it!

[simonbaker]

HELLO.
I thank you despite very that you want me to help.
tgsl I have finished him,
other I am not satisfied from the distance that detects the metals,
it is not big the distance,
that is to say one Euro in the 8 cm.
I believe that it is small the distance.
problem with the segregation of metals,


I will request you if you can,
say to me what to check.
i I will photograph the inductor and tgsl and the clues of oscillograph.

regards

Hi fmnotes - go to this thread: http://www.geotech1.com/forums/showthread.php?t=16122 .

Read the first few messages. They show oscilloscope photos, and where to make the measurements. Such photos will help very much to start with.

Regards,

-SB

[Dennis the Mennis]

Blobtest with videolink

Those are interesting observations by DtM and Habitbraker.


Habitbraker -- what did you mean by "good became bad too..."? Were you talking about actual air-depth detection, or observed phase of null?

There is one electronic consequence of a seriously "wrong" null phase... if you have a large null signal and a phase which makes the voltages on capacitors C12 and/or C15 go negative, you can forward-bias the JFets, which screws up the Synchronous Detector operation and can certainly mess up your detection. So watch for that condition.

It makes sense to me that unshielded coils exhibit a more "ideal" null phase shift. The shield certainly will add some kind of coupling -- my question is, how much of that coupling is "non-magnetic" (not affected by ground ferrite) vs. magnetic.

(side note to self: Something I haven't really considered is: can the ground modulate the "non-magnetic" coupling as well, perhaps through capacitive effects, and to what degree?)

(Another issue I need to think about -- how the null signal phase is affected by the "balance" of the magnetic fields between the coils. Ideally, the balance shouldn't affect the phase, just the magnitude of the pure magnetically coupled signal, since it should just affect the net flux in one direction or another. But is there more to it...?)

I would ask you to do the "ferrite blob" test:

Put a large blob of ferrite in the overlap between your coils. Observe the phase (zero crossings) of the (now much larger) null signal. Is the phase now more similar to the null phase with unshielded coils???

-SB

Laptop back in the air , can connect USB scope again , time for a small test:

I did a 'Blobtest' with the ferrite rods (10cm long) , it didn't matter if I used one or two ferrite cores .

The signals shown are Tx ( green) vs Rx output 7 LF353.

I started with the unshielded coils :

Kept the ferrite rod +/- 30 cm above the coils and lowered them right in between the overlap of the coils.

http://youtu.be/ZAQPJhNk9f8?hd=1 ( causing a little shift to the right )

The next test is with shielded coils and same as described as above.

http://youtu.be/8iG90U8sCdg?hd=1 ( causing a little shift to the left )


And one other question for anyone willing to answer:

I'm still struggling with my detector in DISC mode , I've found some defects and repaired them.

Is this the correct DISC shift ?

Shown : Rx output LF353 vs DISC sample puls / output 1 LM393

http://youtu.be/Q_uSpD_dUrY?hd=1

kind regards,

Danny

Dennis the Mennis

[simonbaker]

Laptop back in the air , can connect USB scope again , time for a small test:

I did a 'Blobtest' with the ferrite rods (10cm long) , it didn't matter if I used one or two ferrite cores .

The signals shown are Tx ( green) vs Rx output 7 LF353.

I started with the unshielded coils :

Kept the ferrite rod +/- 30 cm above the coils and lowered them right in between the overlap of the coils.

http://youtu.be/ZAQPJhNk9f8?hd=1 ( causing a little shift to the right )

The next test is with shielded coils and same as described as above.

http://youtu.be/8iG90U8sCdg?hd=1 ( causing a little shift to the left )


And one other question for anyone willing to answer:

I'm still struggling with my detector in DISC mode , I've found some defects and repaired them.

Is this the correct DISC shift ?

Shown : Rx output LF353 vs DISC sample puls / output 1 LM393

http://youtu.be/Q_uSpD_dUrY?hd=1

kind regards,

Danny

Dennis the Mennis

I realize the blob test if somewhat tricky to do, because you have make sure the signal is symmetrically centered about the "zero" line in order to judge the zero crossings. It should be confirmed by trying to estimate where the peaks occur, and see if those shift accordingly, which means you can't "clip" the signal.

But it did seem the shielded null had a healthy shift. I'll try to look closer to see if I can come to any conclusions .

Your DISC shift range looks fairly healthy -- not quite as much as I usually get. Some old drawings I made indicate mine goes further to the right. I will check with a scope when I get a chance; maybe someone else can take a look also.

At least we know your DISC circuit is working. Can you show us the waveform at the wiper of the DISC pot as you turn the pot back and forth? That might explain some things.

Nice tests, thanks for the excellent videos!

-SB

[habitbraker]

will it help if I post some pictures of mine waveforms? Working nice - 30cm with good signal

[simonbaker]

Laptop back in the air , can connect USB scope again , time for a small test:

I did a 'Blobtest' with the ferrite rods (10cm long) , it didn't matter if I used one or two ferrite cores .

The signals shown are Tx ( green) vs Rx output 7 LF353.

I started with the unshielded coils :

Kept the ferrite rod +/- 30 cm above the coils and lowered them right in between the overlap of the coils.

http://youtu.be/ZAQPJhNk9f8?hd=1 ( causing a little shift to the right )

The next test is with shielded coils and same as described as above.

http://youtu.be/8iG90U8sCdg?hd=1 ( causing a little shift to the left )


And one other question for anyone willing to answer:

I'm still struggling with my detector in DISC mode , I've found some defects and repaired them.

Is this the correct DISC shift ?

Shown : Rx output LF353 vs DISC sample puls / output 1 LM393

http://youtu.be/Q_uSpD_dUrY?hd=1

kind regards,

Danny

Dennis the Mennis

Hi Danny:

On looking closer, I think you were showing the DISC sync pulse compared to the Rx signal -- I thought it was compared to the Tx signal at first.

It would be helpful to do the same video of the DISC sync pulse compared to the Tx signal (because we all have different Rx null signals, so difficult to compare).

Also, I'd like to see a video of the signal at the "wiper" (center) tap of the DISC pot as you rotate the pot, compared to the Tx signal.

Also, I'd like to see the the signal at the output of LF353 pin 1 (connected to one side of the DISC pot) compared to the Tx signal -- just a photo, since it should not change as you rotate the DISC pot.

Cheers,

-SB

[simonbaker]

will it help if I post some pictures of mine waveforms? Working nice - 30cm with good signal

It would be useful to see three photos of the Tx signal (J1-1) compared to the DISC sync pulse (LM393 U102 pin 1) :

1. With DISC pot at minimum setting.
2. With DISC pot at middle setting.
3. With DISC pot at maximum setting.

Thanks if possible!

-SB

[simonbaker]

Laptop back in the air , can connect USB scope again , time for a small test:

I did a 'Blobtest' with the ferrite rods (10cm long) , it didn't matter if I used one or two ferrite cores .

The signals shown are Tx ( green) vs Rx output 7 LF353.

I started with the unshielded coils :

Kept the ferrite rod +/- 30 cm above the coils and lowered them right in between the overlap of the coils.

http://youtu.be/ZAQPJhNk9f8?hd=1 ( causing a little shift to the right )

The next test is with shielded coils and same as described as above.

http://youtu.be/8iG90U8sCdg?hd=1 ( causing a little shift to the left )


And one other question for anyone willing to answer:

I'm still struggling with my detector in DISC mode , I've found some defects and repaired them.

Is this the correct DISC shift ?

Shown : Rx output LF353 vs DISC sample puls / output 1 LM393

http://youtu.be/Q_uSpD_dUrY?hd=1

kind regards,

Danny

Dennis the Mennis

I just took a closer look at your "blob" test with the shielded coil.

I looks like your null signal is around 50 deg from your TX signal with no target.

When the ferrite blob is near, the null phase changes to somewhere between 30 - 35 deg, which is similar to the null phase of the unshielded coil.

That is the point I was trying to make -- that the shield is actually somehow moving your basic null signal phase to 50 deg, but really, as far as ferrite is concerned, the null is still back around 30 deg, because the ferrite is amplifying the "magnetic null" signal (which is the one that the ground mostly affects). So we shouldn't really worry too much about the null phase we normally see.

Now there is something I can't understand about your "unshielded blob test". As you bring the blob close, the null phase hardly changes, which is what I expect, because the unshielded coils have more of a pure "magnetically coupled" null signal. But suddenly, the null shifts to the right in a big jump. I'm not sure why that happens, unless it is because the signal overloads the circuit and the symmetry is corrupted, shifting the zero crossing. Or could your hand have also had some metal, like a ring or watch?

In any case, it is interesting to note that ferrite does shift the null signal of our coils, especially shielded ones, and to me that means that there is a magnetic and non-magnetic component to the coil coupling. And that means that we cannot assume that ground will amplitude-modulate the null signal that we see; rather, it will modulate the magnetic component of the null signal.

This is just theorizing on my part; more experiments might indicate a different theory.

Regards,

-SB

[habitbraker]

It would be useful to see three photos of the Tx signal (J1-1) compared to the DISC sync pulse (LM393 U102 pin 1) :

1. With DISC pot at minimum setting.
2. With DISC pot at middle setting.
3. With DISC pot at maximum setting.

Thanks if possible!

-SB

You got it. In your asked sequence. Both traces 5V/div

[simonbaker]

You got it. In your asked sequence. Both traces 5V/div

Thanks!

Your sync pulse seems to shift about 80 deg or so, which is fine. I notice that at both ends of the pot range it breaks up, which is normal for TGSL design, same as I observed with dfbowers model that he sent me (which works very well).

Hopefully Dennis the Mennis can post equivalent video/photos so we can compare his sync pulse to his Tx signal and confirm if his DISC circuit is similar.

Regards,

-SB

[Dennis the Mennis]

http://www.geotech1.com/forums/showp...postcount=4429

Hallo Danny,

Think you have not a good receive signal, tray to adjust it with the 'receive cap' .

Make a 'Receive Cap' test circuit and see how the receive signal changes...

Hi Ap,

Perhaps a little late ,

I've tried to adjust C9 , the cap. before input LF353 U101b pin 2, to get rid of those spikes on Rx signal , see next image ( Rx output LF353 pin 7 vs Tx )



and there are some improvements on the output of the LF353 pin 1 :
Next picture I've installed 180 pF for C9 : output LF353 pin7 vs output LF353 pin1

It seems that I accidentally posted an animated GIF , looks good , I'll keep it in mind ...




100 pF for C9 : output LF353 pin7 vs output LF353 pin1




and 68 pF for C9 : output LF353 pin7 vs output LF353 pin1



Allthough there could be an improvement in signal ( the spikes become smaller and / or shifts a little ) for my pcb , I can't get a better or worse detection.


The DISC sync pulse stays the same no matter the value of the cap ,BUT only at the beginning and/ or the end of the DISC shift there could be a spike that is influenced by these caps !

The spikes like Habitbraker posted in his last post :

http://www.geotech1.com/forums/showp...postcount=4575


It seems that this part of the circuit is pretty forgiving ...

Originally Posted by simonbaker
Quite excellent DtM! Nice way to show your new scope.

I'm interested also in the LF353 output that drives the sync pulse, what does it look like?

I get those little spikes on the RX signal also. I suspect it is caused by the negative power rail circuitry, but not sure

.

It looks like that the spikes on the Rx signal , only visible with very low residual voltage, are 'generated' internally in the LF 353 , at least they influence each other pretty good .

In the posted images I've set the rulers on the spikes : the spikes appear on the exact same places .
Also when nulling the coils , both spikes stay on the same place despite the shift.

This was just a small observation , perhaps it was told a dozen times in these threads.

kind regards ,

Dennis the Mennis

[Dennis the Mennis]

Thanks!

Your sync pulse seems to shift about 80 deg or so, which is fine. I notice that at both ends of the pot range it breaks up, which is normal for TGSL design, same as I observed with dfbowers model that he sent me (which works very well).

Hopefully Dennis the Mennis can post equivalent video/photos so we can compare his sync pulse to his Tx signal and confirm if his DISC circuit is similar.

Regards,

-SB

Hi Simon ,

These are my settings for the DISC sync pulse vs Tx :

Yes , I was confused while posting the DISC vs Rx , I've had in mind that the Rx was sampled , but as I understand that is not for sure (?) .

DISC potmeter 0% :



and



DISC potmeter at 50% :



and



DISC potmeter at 100% :



and



Also here a little spike as described in previous post : most likely cause C9 ( in my case anyway) .

It seems that the shift of Habitbrakers pcb is a little more shifted to the right and if it works for him I'll have to 'tune' my Rx a little so I can get some discrimination .

It would be helpful to do the same video of the DISC sync pulse compared to the Tx signal (because we all have different Rx null signals, so difficult to compare).

Cheers,

-SB

video DISC sync pulse vs Tx : http://youtu.be/opZh96JHWFc?hd=1

Also, I'd like to see a video of the signal at the "wiper" (center) tap of the DISC pot as you rotate the pot, compared to the Tx signal.

Also, I'd like to see the the signal at the output of LF353 pin 1 (connected to one side of the DISC pot) compared to the Tx signal -- just a photo, since it should not change as you rotate the DISC pot.

Cheers,

-SB

video DISC potmeterwiper vs Tx : http://youtu.be/0-JAuOxsQdg?hd=1


kind regards ,

Dennis the Mennis


ps

Simon ,

You could have been right during the ' Blob test ' ... most likely I've forgot my 24 carat Golden Rolex .

Another Blobtest ?

[fmnotes]

http://imageshack.us/photo/my-images/824/tesoro2.png/
Hello.
This psb tgsl it is right?
It works with these prices of materials that it has?
version tgsl 3 it is better?
I request any it knows it helps me.
I thank