Looking for Goldscan 5c by Eric Foster schematic

[greylourie]

Thanks Geylourie. You are a fan of the issue related to GS5, I follow your comments on this and other forum.
Jose

I am a great fan. I think it should be mandatory for anyone who wants to learn about ground balance, to study the Goldscans and how they can balance out various targets and various ground. The ground, after all is also a target.

[mschmahl]

GS5 4001 This scheme works well
The published for gold escan 5 at the forum, it did not work for me.[ATTACH]37668[/ATTACH]

Thanks for this scheme. The solution on the GS4 is ok if you use the 2x 470k parallel to J113´s. But without the 470k´s it could be an improvement.

I think Reg would be very happy to see that you followed his advice. Replacing those opamps with low-offset ones gets rid of so many trimmers and the tedious setup allied to them.
I don't think your motion mod is a cludge. Very neat work all around.

I think so! Thank´s Reg there are a lot of way´s to make setting up much easier without loosing much depth. With this opamps it should be more possible to build the GS 4 with more success.

[mschmahl]

Thank you for the details, Michael. I would love to see a video of your detector since you made the opamp upgrades.

The accupack arrives me. What do you want to see? Disc or different non-motion settings, or anything else?

[mschmahl]

Here are some videos
different Motion settings
https://youtu.be/JSk93R0KtYo
Low Conducter mode
https://youtu.be/h0oLeVXap3A
High Conducter mode
https://youtu.be/KbwqfQaaXwk

The high conducter mode should be a bit more improved.

I don´t have the 1NF installed that Jose mentioned.
For using the minelab coil I have increased the frequency and build in a resistor in series to the coil with the existing resistor. So I have a shorter Pulse-on-time and reduced the heat because of the low coil R in the minelab coils.

[greylourie]

Hello Michael. Thanks for posting those videos. Could you show the impact of the different motion settings on a small variety of targets, using both a slow and a faster sweep speed ?

[Jose]

Here are some videos
different Motion settings
https://youtu.be/JSk93R0KtYo
Low Conducter mode
https://youtu.be/h0oLeVXap3A
High Conducter mode
https://youtu.be/KbwqfQaaXwk

The high conducter mode should be a bit more improved.

I don´t have the 1NF installed that Jose mentioned.
For using the minelab coil I have increased the frequency and build in a resistor in series to the coil with the existing resistor. So I have a shorter Pulse-on-time and reduced the heat because of the low coil R in the minelab coils.

Thanks for the videos.
The driver high mode, can have a low yield due the design GS4, and the separation of both channels.
In the GS5, the channel separation was reduced, also it has more gain than its predecessor GS4.
Capacitor 1 nF, It was omitted apparently in scheme Papa Alex.
Jose

[Orbit]

Thanks for the videos.
The driver high mode, can have a low yield due the design GS4, and the separation of both channels.
In the GS5, the channel separation was reduced, also it has more gain than its predecessor GS4.
Capacitor 1 nF, It was omitted apparently in scheme Papa Alex.
Jose

Hi Jose ! 1nf does not exist in the original gs4 scheme .

[greylourie]

Hi Jose ! 1nf does not exist in the original gs4 scheme .

Hello Orbit, it was not in schematic. But it was in original design. If you search forums, you can see photos with that 1nF capacitor.

http://www.geotech1.com/forums/showt...103#post127103

[Orbit]

Hello Orbit, it was not in schematic. But it was in original design. If you search forums, you can see photos with that 1nF capacitor.

http://www.geotech1.com/forums/showt...103#post127103

That this capacitor ? This is an original design gs 4 !

[mschmahl]

Hello Michael. Thanks for posting those videos. Could you show the impact of the different motion settings on a small variety of targets, using both a slow and a faster sweep speed ?

There is no difference if you swing fast or slow. You have to swing slow, to get good depth. The difference is how fast the GS4 will go to silent if you stop over a target. The best depth is with non-motion mode (switch to off), than 4.7 M ohm switched in and than 470 k ohm switched in. But sometimes you have a lot of noise outside so you must switch to 4.7 M ohm (sometimes to 470 k Ohm) so that you can search.


https://youtu.be/7Ic2Ia7IofA

[mschmahl]

Hello Orbit, it was not in schematic. But it was in original design. If you search forums, you can see photos with that 1nF capacitor.

http://www.geotech1.com/forums/showt...103#post127103

That this capacitor ? This is an original design gs 4 ![ATTACH]37699[/ATTACH]

Capacitor 1 nF, It was omitted apparently in scheme Papa Alex.
Jose

Sorry, yes this capacitor is in. I have forgot it. Had a discusion about it some time ago. Here is the picture, it is marked with "Missing cap", the slightly burned red cap.

[greylourie]

Hello Michael
The large coin used in your videos, is it similar to the ones you are searching for out in the field ?

[mschmahl]

Yes. But it is a more modern. .999 fine silver 1 OZ from 2012. But the size and material is similar.

[greylourie]

disclupe not understand the question. But I plowed some comments.
I understand what I can read in the forum that the LME49990 is one of the amplifiers with more low noise level, so it is very good choice for the front.
Same with the LT1114, which also can better compensate the output voltage, "Offset Voltage" with different temperature.
I do not replace the LME49990, or the LT1114 in my GS4.
As for the resistors 470 K, I Use 1M, I notice that something more gain.
Something I forgot to mention here, but I mentioned before, is that the resistance of 220K in leg 8 of IC 2, was replaced in me GS4, a R 22 K, and it worked better.
GS4 integrator, has a very quick response, which favors the detection of small objects, and limits according to my poor understanding, the size of the coils.
It can be altered experimentally, the value of resistors 68K integrators in both channels, when larger coils thus improving the signal to noise ratio are used.
I installed a switch to perform this function.
I do not know if it answers your question.
Jose

Hello Jose,

What you say is very interesting. If you look at this post (http://www.geotech1.com/forums/showt...358#post219358) Mr Foster says, "In the differential version the loop gain controls the time constant, so you can have an external pot to vary the 'response speed' or 'noise averaging'."

[Jose]

.... Yes, in fact we have followed the ideas of Mr. Foster.
We are also observed, a practical example in the scheme of Superscan.
Jose