Archaeology Resistivity Meter

Hi Michael,

I had these initial thoughts, but I've not had time to think things through (I have some time late Wednesday to do that):

There was mention of more sense probes, but maybe the expansion interface is sufficient for that, since one could drive (say) a latching relay via that. Or maybe space for on-board relay?

A minor point was, for the USB UART, for MCP2221 I already have Android code. But FTDI is totally fine too, i.e. if you've already got the schematic entered for that portion then it's quicker for me to just hunt for demo code for FTDI, if you let me know the chip number. Below is the the schematic I've used previously for the MCP2221 (it needs an external 3.3V regulator which probably the FTDI device doesn't, and has 4kV protection which likely isn't enough, I didn't place any additional ESD protection on this schematic).

One other thought was for a test facility, if there was were four jumpers or four DIP switches on the board which would connect a potential divider across the source (two switches for that) and two switches to connect the sense wires to the divider. Maybe jumpers are easier. But probably there will be test points on the board for easy soldering of a mini test harness during software development anyway.

Hi Michael,

Sorry for the feedback delay.

I saw the post, and wished to look at it, but have not had as much time as hoped this week.

However, I get a lot more free from tomorrow evening, so I will look through it then!

That's OK, I just need to feel that there is enough enthusiasm to carry the thing forward.

kltm, it'll be hard to model exactly in LT spice because the amplifiers are TI parts, they won't make much difference so use an AD part that looks close (or the Universal Op Amp model)

I've got an LT Spice of some of it which I've added here.

Version 4
SHEET 1 1916 864
WIRE 224 -160 80 -160
WIRE 224 -128 224 -160
WIRE 192 -112 -160 -112
WIRE 304 -96 256 -96
WIRE 400 -96 304 -96
WIRE 528 -96 480 -96
WIRE 560 -96 528 -96
WIRE 192 -80 144 -80
WIRE 304 -48 304 -96
WIRE 224 -32 224 -64
WIRE 224 -32 64 -32
WIRE 144 64 144 -80
WIRE 304 64 304 32
WIRE 304 64 144 64
WIRE 1280 112 1024 112
WIRE 80 144 80 -160
WIRE 656 144 80 144
WIRE 656 176 656 144
WIRE 528 192 528 -96
WIRE 624 192 528 192
WIRE 832 192 768 192
WIRE 960 192 912 192
WIRE 1072 192 960 192
WIRE 1200 192 1152 192
WIRE 768 208 768 192
WIRE 768 208 688 208
WIRE 624 224 528 224
WIRE 1024 240 1024 112
WIRE 64 272 64 -32
WIRE 656 272 656 240
WIRE 656 272 64 272
WIRE 960 288 960 192
WIRE 992 288 960 288
WIRE 1200 288 1200 192
WIRE 1200 288 1152 288
WIRE 992 320 928 320
WIRE 560 336 560 -96
WIRE 304 352 144 352
WIRE 992 352 960 352
WIRE 1200 352 1152 352
WIRE 304 384 304 352
WIRE 64 416 64 272
WIRE 224 416 64 416
WIRE 832 448 816 448
WIRE 960 448 960 352
WIRE 960 448 912 448
WIRE 1072 448 960 448
WIRE 1200 448 1200 352
WIRE 1200 448 1152 448
WIRE 224 464 224 416
WIRE 144 480 144 352
WIRE 192 480 144 480
WIRE 304 496 304 464
WIRE 304 496 256 496
WIRE 400 496 304 496
WIRE 528 496 528 224
WIRE 528 496 480 496
WIRE 624 496 528 496
WIRE 768 496 768 208
WIRE 768 496 704 496
WIRE 192 512 -48 512
WIRE -160 544 -160 -112
WIRE -48 544 -48 512
WIRE 80 560 80 144
WIRE 224 560 224 528
WIRE 224 560 80 560
WIRE 928 576 928 320
WIRE 560 592 560 416
WIRE 64 608 64 416
WIRE 224 608 224 560
WIRE 1280 608 1280 112
WIRE -160 640 -160 624
WIRE -112 640 -160 640
WIRE -48 640 -48 624
WIRE -48 640 -112 640
WIRE -112 656 -112 640
WIRE -112 752 -112 736
WIRE -112 752 -160 752
WIRE 64 752 64 688
WIRE 64 752 -112 752
WIRE 224 752 224 688
WIRE 224 752 64 752
WIRE 352 752 224 752
WIRE 560 752 560 672
WIRE 560 752 352 752
WIRE 816 752 816 448
WIRE 816 752 560 752
WIRE 928 752 928 640
WIRE 928 752 816 752
WIRE 1024 752 1024 400
WIRE 1024 752 928 752
WIRE 1280 752 1280 688
WIRE 1280 752 1024 752
WIRE 352 784 352 752
FLAG 352 784 0
SYMBOL Opamps\\UniversalOpamp2 224 -96 M180
SYMATTR InstName U1
SYMBOL Opamps\\UniversalOpamp2 224 496 R0
SYMATTR InstName U2
SYMBOL res 496 -112 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 6K
SYMBOL res 496 480 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 6K
SYMBOL res 288 368 R0
SYMATTR InstName R8
SYMATTR Value 1k
SYMBOL res 288 -64 R0
SYMATTR InstName R9
SYMATTR Value 1k
SYMBOL voltage 64 592 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 16
SYMBOL voltage 224 592 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value -16
SYMBOL voltage -48 528 R0
WINDOW 3 -130 -53 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value SINE(0 15 100 0 0 180)
SYMATTR InstName V4
SYMBOL voltage -160 528 R0
WINDOW 3 -182 -3 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value SINE(0 15 100)
SYMATTR InstName V5
SYMBOL voltage -112 640 R0
WINDOW 3 -182 -3 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value SINE(0 .01 2)
SYMATTR InstName V8
SYMBOL Opamps\\UniversalOpamp2 656 208 M180
SYMATTR InstName U3
SYMBOL res 720 480 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 1K
SYMBOL res 544 320 R0
WINDOW 3 47 73 Left 2
SYMATTR InstName R2
SYMATTR Value 1K
SYMBOL voltage 560 576 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 0
SYMBOL Opamps\\LTC6362 1056 320 R0
SYMATTR InstName U4
SYMBOL res 1168 432 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R5
SYMATTR Value 1K
SYMBOL res 1168 176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R6
SYMATTR Value 1K
SYMBOL res 928 176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 1K
SYMBOL res 928 432 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R10
SYMATTR Value 1K
SYMBOL voltage 1280 592 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V6
SYMATTR Value 5
SYMBOL cap 912 576 R0
SYMATTR InstName C1
SYMATTR Value 0.1µ
TEXT -312 832 Left 2 !.tran 0 1 0 10e-6

cstanton The tag and group thing seems to work OK once you get used to it !

Thanks.

MK

Hi Michael,

I think this is one of the more exciting projects I have seen in a while but I will be following rather than contributing to the analog part as it is over my head and I don't have the background.  Somewhere in the boxes from my recent move is a NUCLEO-L4R5ZI board and I need to get that going.  The FPGA is going to be a learning experience as well.  I appreciate greatly the work that you and Shabaz are putting into this.

Frank

Nice to hear from you, is your house moving all done now ?

MK

I think a lot of people are contemplating a build.

Until you have the circuit connected to the sensors and see how it performs you are kind of at an impasse.

It would be awesome if someone who uses this system did a side by side comparison of its capabilities.

DAB

All my things are in the house and though it is the same size as the old house the layout is different with little built-in storage and I am finding my things don't fit well.  So unopened boxes are waiting for me to create storage and shelving.  And it hasn't been lived in for several months so I am also having to whack the garden back into shape.  It is a nice house in a great area though....

All takes time Frank. I guess it’ll take a few months to sort. Good luck

fmilburn Frank it never ends I moved about 1.5 years ago I have 40-50 boxes in the storage, plus my garage is getting full. Consider this, I have a DB one table, LOL where all my boxes are numbered as well as what room they came from and what's in them as well as the type of box.  GRON I still have stuff from my kitchen mia, and I can't find a DVM as well as my hot air solder station. LOL

~~Cris

BTW i started with over 160 boxes.

I started putting in shelving today :-)

fmilburn Good luck, frank I'm still putting up shelving! Lots of Elfa top mounting rails, and standards. Rubbermaid etc (Home Depot) for the brackets (cheaper price). And sometimes I buy them from my Goodwill outlet store where it's only $1.50 a pound. I also have some Metro wire shelves, and some HomeDeopt plastic shelves. In my garage, I put together a bunch blue of 2x4x6 used shelves with nuts and bolts ( pain in the ass!) so have about 20 feet of that stuff. And I still need to put together a workbench down there as well. for a drill press and other things. Currently building a 12' long clothes rack, from 2x4s and two uprights from the blue shelves. Not quite a 3-foot base but all the way to the ceiling made like two right triangles. And its bolted together, with a cross brace near the top to rest the steel on.

fmilburn Good luck, frank I'm still putting up shelving! Lots of Elfa top mounting rails, and standards. Rubbermaid etc (Home Depot) for the brackets (cheaper price). And sometimes I buy them from my Goodwill outlet store where it's only $1.50 a pound. I also have some Metro wire shelves, and some HomeDeopt plastic shelves. In my garage, I put together a bunch blue of 2x4x6 used shelves with nuts and bolts ( pain in the ass!) so have about 20 feet of that stuff. And I still need to put together a workbench down there as well. for a drill press and other things. Currently building a 12' long clothes rack, from 2x4s and two uprights from the blue shelves. Not quite a 3-foot base but all the way to the ceiling made like two right triangles. And its bolted together, with a cross brace near the top to rest the steel on.

phoenixcomm Yep, I'm started with some metal wire shelving that is quick to put up in the garage and then building some 2x4 made to fit next.  I almost spent more time opening boxes to find the necessary tools than putting up shelves.

fmilburn " I almost spent more time opening boxes to find the necessary tools than putting up shelves." sounds very familiar!