Voodoo Main Discussion

[6666]

Work fine without one. It?s getting averaged out but ideally should have one.

Thanks.

[dfbowers]

Hi Don, did you catch this question ?

Work fine without one. It?s getting averaged out but ideally should have one.

[6666]

Don, I would have expected a capacitor after the CD4066B to hold the sampled voltage; it's really missing?

Hi Don, did you catch this question ?

[dfbowers]

Yes.. that would be a great idea. If nothing else this has been a fun experiment, I will probably try to move everything off my breadboard onto a copper version next and try real world. Also looking forward to assembling the VooDoo!

[6666]

Done:
[ATTACH]54139[/ATTACH]

Great work, for U1, I would use a normal 555 with a 100uF across it.

[surfdetector]

You can remove the 1k resistor.. just a leftover from a previous drawing. It works without an offset because it get filtered out later on but good idea to add one. The other two, I Donno but will check my original board.
also, playing around, its best to keep the sample width a little smaller. I changed R47 from 22k to 15k.

Could R47 be a Pot instead?

[ivconic]

Done:

[dfbowers]

You can remove the 1k resistor.. just a leftover from a previous drawing. It works without an offset because it get filtered out later on but good idea to add one. The other two, I Donno but will check my original board.
also, playing around, its best to keep the sample width a little smaller. I changed R47 from 22k to 15k.

[ivconic]

I also have 4 questions for Don, i put circles on schematic where i need clarifications.
Corrected:

[Altair]

I corrected those.
Software for opening, editing and manipulating with this format is full free and can be downloaded here:
https://www.expresspcb.com/

[ATTACH]54131[/ATTACH]

.... out pins 6,8,10 of 40106 must be left open!

[dbanner]

Don, I admire your work, thank you for your efforts. There is simply no way in which one can make a usable detector based on running up same street over and over. Let's face it. Probing the depths of GB with pi is futile, you may end up with a very sophisticated Analog device that only you know how to use.

[ivconic]

I corrected those.
Software for opening, editing and manipulating with this format is full free and can be downloaded here:
https://www.expresspcb.com/

[Altair]

Ivconic,
the IRF9640 is a P channel, not N as in yours schematic and his S and D pins must be swapped.
Moreover, sometime you name -v the -5V.

[Orbit]

There are definitely solutions for the soil

[green]

In a VLF design the problem with heavily mineralised non-homogeneous ground arises in the GB channel, because the selected GB sample point cannot handle the varying ground conditions. The same applies to the GB sample method used in PI detectors, because the target hole created by the GB sample also cannot handle the varying ground conditions. On the other hand, if the ground mineralization is homogeneous then either method would work.

Think I've read somewhere that ground X signal varies and ground R signal doesn't. I have some hot ground from California that GB(R signal)with subtraction at the same settings as ground from my yard. Tried looking at X signal when Tx on with IB coil. Requires different sample settings to GB. Recording I made awhile back shows ground decay slope changes with different Tx profiles but the two different ground R signals act the same. Anyone know where to look for some test information that shows ground R signal not the same with different grounds?

Chart Tx,(cc)constant current,(cr)constant rate