LOOKING FOR GOLDSCAN 4 Schematic.

[ivconic]

You could try to make a modification, replacing the J112 with a CD4066. The bad thing about all that is that you have to do it with cables and that is not good, because the cables generate noise and right there the noise is of no interest.

Best is to make new one according to your pcb.
Will see.
In meantime I tried to act too smart and make spiral coil for GS4!
Theory and practice... as per Murphy; it is always proven that in practice everything is always more difficult, sometimes even impossible, while before that everything seemed easy and doable in theory!
It was a big job in Tinkercad to design and calculate such a body for a spiral coil! It turned out perfectly fine! And it printed perfectly fine!
My delight was endless today when I saw how well it turned out.
But when I tried to insert a wire into the channel... my disappointment was endless too!
Because I barely make half a circle and the wire pops out somewhere halfway, what have I not tried!
I struggled for an hour and finally gave up, this is impossible! It is impossible to insert the wire into the channels, 40-50 rounds and keep it still and straight as it should be!
The only way to make a good spiral coil is to print it as a pcb... but before that you need a really very precise calculation. And for the sake of testing, I checked in JLPcb... it wouldn't be very cheap!
Here are some pictures:

[ivconic]

For all those in a sado-masochistic mood... here's an STL file for you to play around with!
You suffer a little too, it's not just me who has to suffer!

[eduardo1979]

Best is to make new one according to your pcb.
Will see.
In meantime I tried to act too smart and make spiral coil for GS4!
Theory and practice... as per Murphy; it is always proven that in practice everything is always more difficult, sometimes even impossible, while before that everything seemed easy and doable in theory!
It was a big job in Tinkercad to design and calculate such a body for a spiral coil! It turned out perfectly fine! And it printed perfectly fine!
My delight was endless today when I saw how well it turned out.
But when I tried to insert a wire into the channel... my disappointment was endless too!
Because I barely make half a circle and the wire pops out somewhere halfway, what have I not tried!
I struggled for an hour and finally gave up, this is impossible! It is impossible to insert the wire into the channels, 40-50 rounds and keep it still and straight as it should be!
The only way to make a good spiral coil is to print it as a pcb... but before that you need a really very precise calculation. And for the sake of testing, I checked in JLPcb... it wouldn't be very cheap!
Here are some pictures:

Why don't you try gluing the thread inside the channel with a hot glue gun? My idea would be to put a little thread inside the channel and then apply a dot of hot glue to hold it and then do the same until you finish the job. You could also hold the thread with pieces of paper tape, etc.

[ivconic]

The channels are too narrow. I've thought about various solutions and haven't found a single good one.

[Altair]

May be you should try filling the channel with some sticky substance, like honey, and then putting the wire inside...

[Jose]

Last thing I done (was lazy to record another video) is to make 25cm coil, 0.3mH / 0.9R.
In All Metal mode with GEB slightly lose; it improved air "depths" to ~15cm on small Roman coin as well as on gold coin.
Not good enough.
Some other works in progress...

Try removing 2R2, and replacing 2.2k with 1K on the front preamp, to see if it improves the gain.
My coils are rudimentary made with cat5, others did not work well.

[Jose]

On my GS4, I used BF245 instead of J113 and it works fine

[reis_43]

@eduardo1979 Eagle program does not open the schema file. Which program should we use to open it?

[eduardo1979]

@eduardo1979 Eagle program does not open the schema file. Which program should we use to open it?

Express SCH

[reis_43]

Express SCH

thank you master

[reis_43]

@eduardo1979 We use the component values in the diagram in the layout pcb drawing without making any changes. Is it true, master?

[eduardo1979]

@eduardo1979 We use the component values in the diagram in the layout pcb drawing without making any changes. Is it true, master?

Yes.

[eduardo1979]

There is a small error on the PCB, but that is very easy to fix. The track that joins VR2 has a small interruption. Otherwise everything is fine.

[reis_43]

@eduardo1979 Thank you for your help

[reis_43]

I guess it will be like this