TESORO GOLDEN SABRE

[simonbaker]

Yes, they are very , very small .
This graph is made on C12 direct output of the FET vs the TX signal, but I had to drag the coin over the coils to see this respons :

[ATTACH]15752[/ATTACH]

I think it is (almost) impossible to see phase relative to the Tx , can't see which one triggers the target signal .

Someone any idea for this : I can ad a mathimatical channel to the scope ( for example A + sqr B ) ?

This next graphs show the results on the outputs of the LM308's
( Green = U105 GB channel and Red = U104 DISC channel)




Detection on piece of Al foil in AM mode :

[ATTACH]15754[/ATTACH]




A nickel Disced out / rejected or 'nulled'


[ATTACH]15756[/ATTACH]


Same nickel at the point to be rejected :


[ATTACH]15759[/ATTACH]


Steel Bottle Cap rejected (as replacement 2 steel washers ) :


[ATTACH]15760[/ATTACH]


Iron discriminated out :


[ATTACH]15761[/ATTACH]





Detection of an 1 Eurocoin in AM mode :


[ATTACH]15753[/ATTACH]





Ferrite slug / bar 10 cm with GB pot set correctly in am mode


[ATTACH]15755[/ATTACH]




Just a small graphical support for anyone's interrest

kind regards ,

Danny

Dennis the Mennis

Nice demonstration of channel responses and ground balancing! Shows again how useful a USB scope is!

-SB

[dfbowers]

TGSL - Eduardo's version Unintended new features?

I have noticed a few characteristics that set Eduardo's version of the TGSL apart from Ivconic's:

1. Improved audio with external speaker

2. Slight improvement in sensitivity.

3. Change in sweep speed required for optimum searching.

The first two were already mentioned in previous post, but #3 above is another observation that I have made over the last few days of experimenting. I'm basing statements on 2 builds of Ivconic's version and 2 builds of Eduardo's version.

On the bench, I have noticed that Eduardo's version can respond to very slow motion of targets over the coil - significantly slower than what is required for Ivconic's version.

On the other hand, I have noticed that I can loose targets in my test garden if the coil is swept too fast. This is not quite as evident with Ivconic's version. In order to locate some buried targets, I had to carefully limit my sweep speed with Eduardo's version.

Just to sort out the difference, I replaced R29, R31, C14 and C17 on Eduaros's version with values equivalant to the what is shown below without changing any other settings.

Sure enough, that was it.

Now, I was wondering, with all the discussion that we have had on the forum about the bandpass stage around U103 if someone could do a spice simulation (if you still have one setup and handy) of the overall frequency response of the TGSL if R29 and R31 were changed to 1M and C14 and C17 were changed to a total value of 11uF.

I don't want to be too hasty to draw conclusions. but a simulation might help to validate my observations.

I don't consider Eduardo's version to have any problems but understanding the differences enhance getting the most from both.

Don

[satdaveuk]

Wireing

Hi all
Im about to start wireing the pots etc to the PCB.
Just wondering before I start this wether it would be a advantage to wire the pots with screened leads like they do in alot of top end HI-FI and test equipment.
Feed back greatfully received.
I got my second set of coils made up which are near the spec required by not winding them so tightly as last time, ive not applied shield yet until ive checked out the PCB is up and running.
All the best

Regards

Dave

[simonbaker]

TGSL Overall Response, Standard Vs. Eduardo

I have noticed a few characteristics that set Eduardo's version of the TGSL apart from Ivconic's:

1. Improved audio with external speaker

2. Slight improvement in sensitivity.

3. Change in sweep speed required for optimum searching.

The first two were already mentioned in previous post, but #3 above is another observation that I have made over the last few days of experimenting. I'm basing statements on 2 builds of Ivconic's version and 2 builds of Eduardo's version.

On the bench, I have noticed that Eduardo's version can respond to very slow motion of targets over the coil - significantly slower than what is required for Ivconic's version.

On the other hand, I have noticed that I can loose targets in my test garden if the coil is swept too fast. This is not quite as evident with Ivconic's version. In order to locate some buried targets, I had to carefully limit my sweep speed with Eduardo's version.

Just to sort out the difference, I replaced R29, R31, C14 and C17 on Eduaros's version with values equivalant to the what is shown below without changing any other settings.

Sure enough, that was it.

Now, I was wondering, with all the discussion that we have had on the forum about the bandpass stage around U103 if someone could do a spice simulation (if you still have one setup and handy) of the overall frequency response of the TGSL if R29 and R31 were changed to 1M and C14 and C17 were changed to a total value of 11uF.

I don't want to be too hasty to draw conclusions. but a simulation might help to validate my observations.

I don't consider Eduardo's version to have any problems but understanding the differences enhance getting the most from both.

Don

Just happen to have a sim here in my hip pocket...

You observations are in line with what I would expect -- slower filter section (lower center frequency) should do all those things. Eduardo's mods make a filter centered at about 6 Hz while standard TGS filter centers at about 9 Hz (if my sim is accurate). Eduardo's overall gain is also about 7 dB higher also, which may or may not be desirable.

For laughs I once built a TGSL centered at about 1 Hz I recall -- out-of-control! But had greater depth, at penalty of much slower sweep speed and crazy lag to the beep after passing target.

Response is an interesting variable to play with -- one of my goals is to build a TGSL with user-selectable response (slow, medium, fast, etc). Digital processing is probably the most sane way to develop it.

I have long felt that the original TGS was designed for smaller coils and faster response (to help pinpointing and easier feel), depth not so important. Since most people here seem to favor depth, larger coil and slower response seems a natural choice.

I'm interested in more of your field experience on how useful a slower response really is, and what you think the sweet spot response should be.

Regards,

-SB

[dfbowers]

Thanks Simon.. I always knew that you had deep pockets!
Your graph didn't look like much at first glance but then I realized that it's a log scale.
By your sim, that should show the need to slow down sweep speed to about 3/4 of what is normally needed. It might even be a bit slower that that in actual use but I guess it depends upon your searching habits. Again, I think that this circuit is very useful but there is a need to know where the optimium sweep speed is to take advantage of the extra gain.

On a side note, one other undesireable thing that I came across is that in the A.M. mode, this versions seems to be a little unstable, even at reduced sensitivity settings. Getting away from noise sources helps a lot though.

Don

[Ed Mac]

Newbie to forum

Hello to everyone! I've been reading this forum for a few months now and finally decided to join. I watched the TGSL grow from a spark to a full fledged project involving a whole lot of very smart people. I recently decided to build one myself following Ivonic's details.
I built the electronics and then the coils but upon potting the coils the whole thing warped and I need to statr the coil process all over. I got fairly poor results before i pooted the coils but I figured it was my first try and chalked it up to that. Hopefully my next set will be better. One thing I noticed was the battery test when poering on was not a loong beep as I've seen described but a rather short one ( less the 1/2 a second ) and something I haven't seen mentioned ( or just missed it) is upon powering off I hear more tones 2 "beeps" and a "boop" like caps disharging? Any thoughts on that ??
Thanks to all This is a great forum!
Ed

[satdaveuk]

Im going to build that coil tester that was mentioned earlier on the thread, will be a god send far as making coils up in the workshop.

Hope all is well everyone

Dave

[habitbraker]

Hello to everyone! I've been reading this forum for a few months now and finally decided to join. I watched the TGSL grow from a spark to a full fledged project involving a whole lot of very smart people. I recently decided to build one myself following Ivonic's details.
I built the electronics and then the coils but upon potting the coils the whole thing warped and I need to statr the coil process all over. I got fairly poor results before i pooted the coils but I figured it was my first try and chalked it up to that. Hopefully my next set will be better. One thing I noticed was the battery test when poering on was not a loong beep as I've seen described but a rather short one ( less the 1/2 a second ) and something I haven't seen mentioned ( or just missed it) is upon powering off I hear more tones 2 "beeps" and a "boop" like caps disharging? Any thoughts on that ??
Thanks to all This is a great forum!
Ed

Which version did you build? TGS or TGSL? TGSL doest have battery test...
And its normal that it makes small beeps on powering on moment.

[Ed Mac]

TGSL

Which version did you build? TGS or TGSL? TGSL doest have battery test...
And its normal that it makes small beeps on powering on moment.

Hi habitbreaker and thanks for the quick reply.

I built the TGSL posted in the sticky and developed by Ivconic (as well as many other contributers) using all the same components recommended in the parts list.
I know the unit has that beep when powered up but I have not read anyhing thing about sounds when powering off. Was wondering if they too were normal or if something is awry.
Thanks
Ed

[habitbraker]

Hi Ed!

This is video made by member Dfbowers http://www.youtube.com/watch?v=Nx4Oxac0Ufg

He will turn it on and off. You can compare. (Also performance.)

Those transient sounds are compleatly normal to have!

[manurespreder]

Hi there i was wondering about power supply for my tgsl what the optimal apms should be.. is it enough aroung 1A?

[habitbraker]

Do you mean how much Ah should battery have? If yes, then 1Ah is plenty enough!
TGSL consumes about 30mA so do your calculations to mach your desired battery life.

[manurespreder]

Hello there again i am novice in electronics and i don't know why i started with project like that so there is no surprise that my detector is still not working

i made coils from 0,3mm cu and inductance for RX is 6,45 and 5,9 for TX using usb2 cable to connect coils with circuit there is gap about 10mm in both coils. When i turn my tgsl on it make no sound at all only little noise on power up.

When i tried to change RX connection on circuit i made some noise and burned out resistor 22 Ohm's near power supply i changed it and same situation again. I am testing circuit without changes where changed resistor from 22 to 100

Now i am wondering where is my problem any thought to share with me to get my project done?

i still waiting for oscilloscope to arrive for balancing/nulling but i guess it still should work without balancing but with ugly performance?

[Wiltran]

tgsl

Manure spreading guy, go back and flip the board over, get a good magnifier, and look for solder bridges etc. Then check orientation of transistors and ics. Make sure you have a good power supply and getting good regulation. This is a process of elimination. It would help to have a freq. counter to see if transmitter is working.

[dfbowers]

Manure spreading guy, go back and flip the board over, get a good magnifier, and look for solder bridges etc. Then check orientation of transistors and ics. Make sure you have a good power supply and getting good regulation. This is a process of elimination. It would help to have a freq. counter to see if transmitter is working.

Check to see if you have -5v (could be as high as -6.2) . That will tell you whether or not your oscillator is working.

Don