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Archaeology Resistivity Meter

kltm

Hi I'm looking for ideas on an update to a resistivity meter for archaeology. The only published designs for diy were in 2 magazines. One was published in 1997 and the other in 2003. I have copies of both articles available. The reason behind this is the current high cost of available equipment, usually well beyond the reach of most archaeological groups. I've attached a basic block diagram. In the first magazine article the meter is very basic. It relied on the operators to write down the reading given as the survey was taken. Given that a normal survey grid is 20m x 20m and 1 reading is taken on every sq mtr there would be 400 readings to write down and then input into a program used to interpret the results. The later article is really an update to the first where a PIC has been added to record the readings. This again is prone to error, because eadings are taken manually by pressing a button.

I'm sure given the advances in electronics there must be better ways. 

 

 

 

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  • in reply to kltm

    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.

     

    image

  • in reply to michaelkellett

    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

  • in reply to fmilburn

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

     

    MK

  • in reply to michaelkellett

    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

  • in reply to michaelkellett

    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....

  • in reply to fmilburn

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

  • in reply to 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.

  • in reply to phoenixcomm

    I started putting in shelving today :-)

  • in reply to 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. image 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 ( image 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. image

  • in reply to 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.

  • in reply to fmilburn

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

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