TGSL Tuning & troubleshooting

[der_fisherman]

I do understand what you mean and I am not happy about it either.

At very least, this entire forum owes him a huge thank you for the contributions he has made. There are a lot of people that now have very nice TGSL, IGSL, SMW and other metal detectors as a result of his imagination and hard work.

This place is not the same without him.

Jerry

I hope he is still around, keeping a friendly eye on us from time to time too.....
Regards
andy

[Jerry]

I am verry unhappy I hope we did not lost Ivconic in our forum. Hope you understand what i mean.

I do understand what you mean and I am not happy about it either.

At very least, this entire forum owes him a huge thank you for the contributions he has made. There are a lot of people that now have very nice TGSL, IGSL, SMW and other metal detectors as a result of his imagination and hard work.

This place is not the same without him.

Jerry

[Wiltran]

TGSL Threshold Sound

When you are using the TGSL, or other similar VLF detector, in all metal mode, are you supposed to hear a faint static sound after you adjust the gain control, or it it supposed to be dead silence?

[johnsmith77]

I am verry unhappy I hope we did not lost Ivconic in our forum. Hope you understand what i mean.

[Jerry]

Hi Jerry ,

perhaps this is of any use ( though there must be another million examples) ....

http://www.pi4raz.nl/index.php?option=com_content&task=view&id=223&Itemid=46

[ATTACH]17344[/ATTACH]

kind regards ,

Danny

Dennis the Mennis

Thanks, I will give that a try also. It would be nice to find one of these that works well enough.

Jerry

[simonbaker]

Hi Jerry ,

perhaps this is of any use ( though there must be another million examples) ....

http://www.pi4raz.nl/index.php?option=com_content&task=view&id=223&Itemid=46

[ATTACH]17344[/ATTACH]

kind regards ,

Danny

Dennis the Mennis

Can someone explain what R3 and D3 do in this circuit of attachment 17344? At first glance it would seem they would distort the negative half of the waveform - ???

-SB

[Jerry]

Johnsmith77: The one I have does have it's own internal generator that will go up to 20 khz. That isnt the problem. Besides the hum, which I can eliminate, it is under sampled to the point where it departs from displaying a nice sine wave above about 6 khz. It shows a signal all the way up to 20 khz but it is no longer a nice sine wave like on my oscilloscope.

Even with this, I want to make some tests along side of my regular test equipment to see how accurate it is on measuring phase and frequency. It does not have to look pretty as long as it produces some usable results.

If it can it will be a huge boon for those that do not have access to better test equipment.

But I really need to see it before I can form an opinion.

Jerry

[simonbaker]

1) How do you think how Ivconic got loud sound even at 46 cm distance while others has only weak beeps?

555 timer as mentioned above? Or one of TGSL mods?

http://www.youtube.com/user/ivconic#p/u/14/CxUOcCQBqU4

This is not something mortals should attempt.

2) I have an idea. Put switch which connects to ne555 delay circuit (for example). We will have constant sound volume at all distance. And will not miss deep small and weak sound objects.
When object detected, switch to normal sound mode, which sound volume depends on deepth. And will how deep is treasure

Will not miss any object ir loudly places, like seashore and will know deepth

Actually, the cheapest Tesoro MD, the Compadre, has constant volume. When signal gets very weak, it will finally break up and become noisy.

I used to think I would like variable volume, as indication of depth. But I realize -- why would I want deep objects to be faint? Then I might miss them completely.

So I am content with constant volume and prefer it. I test depth by duration of beep, sweep angle, varying sweep speed, and raising the search head above the ground.

3) After i wrote this, I have read previous tgsl post and see that idea was made by ivconic more earlier.

Salih i think now you know what to do

Yes, that mod is available. Your idea of switching between audio modes is certainly a feature you may want to try and let us know how you like it.

-SB

[johnsmith77]

I think it is because the inputs were not terminated with anything. I did not have the time to play around with it much today but what I have done in the past with sound cards is transformer isolate the inputs. It would be nice I can get this working well enough to see agreement with the other test equipment I have. Will report back when I have something.

Jerry

Before making a proper cable, you can just test with sweepgen at frequency 14.5khz. And need download and install e2soft virtual sound card. Then make it as default in pc. After this you can use all internall pc sounds, not only from mic, line inputs. This will show how triggering is working, the first impresion may be not good. But when you have no other dual trace scope, you have no choice (i am talking about myself then it takes some time to understand what it's showing when triggering is a little sweeping. But it is possible.

[Jerry]

Also can try zelscope. Is has a little wider range of timebase.
Do you have stereo mic input or stereo line in? Usually mic inputs are mono.

www.zelscope.com

Wonder what makes 60hz hum? Input from mic?

I think it is because the inputs were not terminated with anything. I did not have the time to play around with it much today but what I have done in the past with sound cards is transformer isolate the inputs. It would be nice I can get this working well enough to see agreement with the other test equipment I have. Will report back when I have something.

Jerry

[johnsmith77]

Also should install virtual sound card if want use internal signal generator as source.

[johnsmith77]

Very good suggestion! I already have a good scope so it is more difficult to justify yet another toy, but it does offer some advantages over a conventional scope.

I downloaded a PC sound card oscilloscope this afternoon just to see if it was usefull for TGSL frequencies. From what I have seen so far I have to say no. But I was using the internal signal generator for a source and not a properly terminated input. 60 hz noise was a problem along with the sample rate. If the hum is eliminated then just maybe it will work somewhat.

This is the one I tried: http://www.zeitnitz.de/Christian/scope_en

I am going to make up a proper input cable for it and give it one more test before passing final judgement.

Jerry

Also can try zelscope. Is has a little wider range of timebase.
Do you have stereo mic input or stereo line in? Usually mic inputs are mono.

www.zelscope.com

Wonder what makes 60hz hum? Input from mic?

[johnsmith77]

My previous suggestion (with bigger capacitors) was to make the beep longer, in case your problem is too short a beep with weak targets.

However, if your real problem is simply loudness, then you can try this:

Disconnect the 100k resistor R40 from U105 pin 6 (output of LM308 GB channel) and connect it to V+ voltage.

This should help give you same volume sound for all beeps (except very short ones). But it may be too loud, so you may need to use a voltage divider to get smaller voltage than V+.

P.S. I haven't tried this so you would need to experiment.

-SB

1) How do you think how Ivconic got loud sound even at 46 cm distance while others has only weak beeps?

555 timer as mentioned above? Or one of TGSL mods?

http://www.youtube.com/user/ivconic#p/u/14/CxUOcCQBqU4

2) I have an idea. Put switch which connects to ne555 delay circuit (for example). We will have constant sound volume at all distance. And will not miss deep small and weak sound objects.
When object detected, switch to normal sound mode, which sound volume depends on deepth. And will how deep is treasure

Will not miss any object ir loudly places, like seashore and will know deepth

3) After i wrote this, I have read previous tgsl post and see that idea was made by ivconic more earlier.

Salih i think now you know what to do

[Dennis the Mennis]

Very good suggestion! I already have a good scope so it is more difficult to justify yet another toy, but it does offer some advantages over a conventional scope.

I downloaded a PC sound card oscilloscope this afternoon just to see if it was usefull for TGSL frequencies. From what I have seen so far I have to say no. But I was using the internal signal generator for a source and not a properly terminated input. 60 hz noise was a problem along with the sample rate. If the hum is eliminated then just maybe it will work somewhat.

This is the one I tried: http://www.zeitnitz.de/Christian/scope_en

I am going to make up a proper input cable for it and give it one more test before passing final judgement.

Jerry

Hi Jerry ,

perhaps this is of any use ( though there must be another million examples) ....

http://www.pi4raz.nl/index.php?option=com_content&task=view&id=223&Itemid=46

kind regards ,

Danny

Dennis the Mennis

[Jerry]

Maybe Dennis the Mennis can also talk you (johnsmith77) into getting a PC PicoScope which he has used very successfully. I'd like to get one myself.
-SB

Very good suggestion! I already have a good scope so it is more difficult to justify yet another toy, but it does offer some advantages over a conventional scope.

I downloaded a PC sound card oscilloscope this afternoon just to see if it was usefull for TGSL frequencies. From what I have seen so far I have to say no. But I was using the internal signal generator for a source and not a properly terminated input. 60 hz noise was a problem along with the sample rate. If the hum is eliminated then just maybe it will work somewhat.

This is the one I tried: http://www.zeitnitz.de/Christian/scope_en

I am going to make up a proper input cable for it and give it one more test before passing final judgement.

Jerry