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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. 

 

 

 

image

  • in reply to michaelkellett

    Several of the Chinese board houses offer PCB assembly now and sometimes passives and certain other items are free for something they keep on reels.  I don't have experience but a friend used one successfully a while back in small quantity for a moderately complex board with RF on board.  Is that worth considering?

  • Maybe I jumped the gun a bit, as the instigator, and having a practical use for it I am very interested in this project. I don’t think building one would be beyond my capabilities as I have made loads of analog items over the years. I am pleased to see that all of you are all up for it too.

    Ken

  • in reply to genebren

      wrote:

     

    Ken,

     

    There is still work going on for this project.  The discussions have been moved to another area and split into separate topics.  If you use the search bar at the top of the screen and enter ARMP (for Archaeology Resistivity Meter Project) you will see multiple discussions that are focused on various parts/functions of the project.

     

    Gene

    Oh - I was utterly unaware of "The discussions have been moved to another area and split into separate topics" ; and I guess others, possibly by the looks of it including Ken, who initiated the project, were similarly unaware.

     

    I have been checking this thread every day or two whilst setting up my tests, and have also been aware of the blog post by Michael on the input amplifier solely because he mentioned/tagged me and the bulletin board notified me.

     

    Where is this "other area" Gene?

     

    I hope that the time I have spent on data gathering / writing up haven't been wasted / or that that others haven't wasted their time too.

     

    Dave

  • in reply to kltm

    Hello Ken and Dave

     

    Search ARMP on the front page of E14 or in the Open Source Hardware Group.

     

    This started after the discussion about having our own group.

     

    MK

  • Hi I was certainly aware of the documentation being moved to an ARMP tag as I created it along with help from Shabaz. It’s just a search link to help in finding pertinent diagrams and info in amongst all the other discussion points. As said previously, it would be better if we had a group for this project, but it doesn’t seem to be a possibility on this forum.

    Ken

  • in reply to kltm

    Totally agree about the group thing.

     

    Is anyone keen to offer mechanical design and control layout suggestions.

    Shbaz would lay his out on a tray and I would do the same or stick mine in a bench top type box for development.

    So we need a detailed mechanical concept - I haven't blogged about it but I've thought about it a bit so happy to discuss.

     

    MK

  • I’m pretty sure I could lay this out, I have CAD experience.

  • in reply to kltm

    I'll post a quick blog with the details about sizes of bits that I have and ideas re. boxes in the next few days.

    To get you started,

    the display I suggest (which costs about £30) is a high resolution 4.3" non touch with a built in high level controller.

    The capacity for controls is limited - I'm thinking 1 rotary and 4 buttons.

    The tricky stuff to work out is what standard box to start with - my first thought was a bit pricey at over £30,

    what level of environmental protection, how to install the battery, where the connectors go.

    Then how to attach the pcb and display to the box so you can see the display but water doesn't get in etc.

     

    In a brainstormy way I'm thinking,

     

    plastic box rated IP66, about 9" x 6" x 3"

    top held on by screws (often from back so you can't see them)

    space inside for 2 batteries so you only need to open the box every two days of work to change them

    otherwise some kind of battery door or maybe have them hanging on the outside like a camera

    protect the display with 2mm thick acrylic or polycarbonate

    use IP66 or better rated push buttons but the price is dreadful.

    no good ideas about how to seal the shaft or the rotary control, you could use one of those lovely Chinese CNC encoder wheels

    (about £15) which are surface mounted, but a bit big and pricey.

    The usual little Alps 6mm shaft job would need O rings and a bush

     

    Slightly away from mechanical I saw this (after John Wiltrout's scope repair post):

    http://www.hantek.com.cn/products/detail/16176

    The display is a knock off of the Keysight 34465A34465A but quite lovely. Our display is as good as that and it would be nice

    if anyone feels up to designing and coding an interface of that standard (but controlled by one rotary control and 4 buttons !)

     

    MK

  • I usually use Camdenboss boxes. They have a screw on lid with a seal. They also have card slots in the side walls for mounting PCB’s. I would normally print the control panel and mount it under clear acrylic sheet.

  • in reply to kltm

    Hello Ken,

     

    What do you think of this one:

     

    CHDX8-326, this is the ABS version so a very reasonable price of £17.35 for one or £14.38 each for five.

    We could put the display and main pcb in the lid and the batteries in the base.

    That way you would get a field openable box without any engineering work.

    Would still have to holes in the lid for the display and contols but that's inevitable.

     

    (Farnell sell the poly-carbonate version but not the ABS.)

     

    Did you have a different one in mind ?

     

    MK