TESORO GOLDEN SABRE

[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

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

[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

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

[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]

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

[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!

[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

[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

[dfbowers]

Jerry - Im using ordinary kichen oven with electric heating. My shell form barely fits in the oven so that I couldnt afford to make proper frame form my plastic, just about 1cm wide. Because of that, when it plastic heats up, it just drops of the frame. If not in oven, then when I sqeeze it on the wooden form it will

Dfbowers - You actually was my inspiration source. I messed up 2 sheets already.

What thichness have yours? Mines are 1.5mm.

I could heat it so hot it could vacuum form, BUT.. - see aswer for Jerry.

well it didnt melt the plastic, but surely shifted null a lot! I was readjusted the null every 10 minutes while it was still liquid.
After all my null (at LF output) is very small in A (about 200mV) , but phase from -20deg sifted to about +100deg (!!!). (relative to TX)

Despite this I can reject ferrite at middle of GB pot, discrimination is nice, and my air distance for 2cm coin is about 30cm. (really no big difference if phase is not those 20deg..) Lost about 3cm because of epoxy.
I just very anxious to get to the field

I guess I will glue next one like you suggest - one part/area of a coil at time

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!

[fmnotes]

Please tell us what exact point in the circuit you are measuring the voltage. Is it the output of the LF353 pin 7?

If so, the numbers seem to be good.

What is "f=17.0000KHz" ?

Regards,

-SB

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,

[habitbraker]

Jerry - Im using ordinary kichen oven with electric heating. My shell form barely fits in the oven so that I couldnt afford to make proper frame form my plastic, just about 1cm wide. Because of that, when it plastic heats up, it just drops of the frame. If not in oven, then when I sqeeze it on the wooden form it will

Dfbowers - You actually was my inspiration source. I messed up 2 sheets already.

What thichness have yours? Mines are 1.5mm.

I could heat it so hot it could vacuum form, BUT.. - see aswer for Jerry.

well it didnt melt the plastic, but surely shifted null a lot! I was readjusted the null every 10 minutes while it was still liquid.
After all my null (at LF output) is very small in A (about 200mV) , but phase from -20deg sifted to about +100deg (!!!). (relative to TX)

Despite this I can reject ferrite at middle of GB pot, discrimination is nice, and my air distance for 2cm coin is about 30cm. (really no big difference if phase is not those 20deg..) Lost about 3cm because of epoxy.
I just very anxious to get to the field

I guess I will glue next one like you suggest - one part/area of a coil at time

[dfbowers]

My big day!


My vacuumforming failed (too small oven, too thick plastic, too weak vacuum ), so I just bent it vith my hands and hot air gun.

while epoxy cures, it unbalances a coil a bit so while it is still liquid, I put some weight on windings to balance it back. its hot!!

I had a few failures to start with, but now almost all my shells come out perfect. You must get the time in the oven/temp just right!! I would say that I probably wasted 5 sheets of plastic until I figured it out. Also, if your epoxy is getting hot you will have a failure for sure! It must be slow-cure potting type. You can actually melt your shell and it will certainly spoil your null if using the wrong kind! My last coil, I used very little epoxy by filling the ears first, then 2 part foam, then just a thin layer of epoxy on the bottom. It came out very rigid an light!

[Jerry]

What did you use for an oven? I have a pizza oven but am waiting until I can pick up a heat gun before trying it out.

Jerry

[habitbraker]

My big day!


My vacuumforming failed (too small oven, too thick plastic, too weak vacuum ), so I just bent it vith my hands and hot air gun.

while epoxy cures, it unbalances a coil a bit so while it is still liquid, I put some weight on windings to balance it back. its hot!!