Looking for Goldscan 5c by Eric Foster schematic

[mschmahl]

Jose is in all points complete rigth. I use a LME49990 and 2x LT1114. I have a switch to switch between 470 k and 4.7 M parallel to the two J113´s.

[greylourie]

My vote goes to Jose's version of the alexismex schematic for the Goldscan IV. http://www.geotech1.com/forums/attac...4&d=1478109228
Great job, Jose. https://www.youtube.com/watch?v=GEd9_PoW9bE

[greylourie]

Jose is in all points complete rigth. I use a LME49990 and 2x LT1114. I have a switch to switch between 470 k and 4.7 M parallel to the two J113´s.

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

[Jose]

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

[Jose]

My vote goes to Jose's version of the alexismex schematic for the Goldscan IV. http://www.geotech1.com/forums/attac...4&d=1478109228
Great job, Jose. https://www.youtube.com/watch?v=GEd9_PoW9bE

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

[Tim]

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

Very good Jose, as I will later make one for small items, this will be very helpful!

[mschmahl]

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

Sorry Greylourie, I have to wait to get my accupack back. Maybe I can make a video tomorrow.

I have wrote about a different part. LT1114 is useable but I have 2x OPA4277PA inside my goldscan.

Jose is in all points complete rigth. I use a LME49990 and 2x LT1114. I have a switch to switch between 470 k and 4.7 M parallel to the two J113´s.

[mschmahl]

Pictures after modification

Here are some pictures. See how much parts I could remove because of no need for offset the better IC´s.

[Tim]

mschmahl, could you possibly upload an original schematic, with the omitted parts crossed out, and replacements marked?

[mschmahl]

Motion Mod

Additional I have cluged in a switch for the motion-function of the Goldscan (470k Ohm parallel to J113)
It is a double 3-way switch. If you switch right, you have 470 k Ohm, if you switch left you have 4,7 M Ohm parallel to both J113. If you switch to the middle, you are in original non-motion mode.

[mschmahl]

High conducter mode

mschmahl, could you possibly upload an original schematic, with the omitted parts crossed out, and replacements marked?

I will do it, wait a bit.

I have also build in a sort of high conducter mode, with help of some ideas from jose.

[mschmahl]

Here is the changed schematic.

One other Idea (not tested) is to make the reset with help of a CD4001 similar to the Goldscan 5. And I would like to have a two-tone signal generator, maybe with help of a CD4046. But than we have to rework a lot of the circuit.

[eclipse]

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.

There are few alternative integrator ideas published by Teleno for the MPP, which is similar.
Perhaps this is worth trying out.

[Jose]

Here is the changed schematic.

One other Idea (not tested) is to make the reset with help of a CD4001 similar to the Goldscan 5. And I would like to have a two-tone signal generator, maybe with help of a CD4046. But than we have to rework a lot of the circuit.

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

[greylourie]

Here are some pictures. See how much parts I could remove because of no need for offset the better IC´s.

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.