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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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  • Certainly possible to do much better than the design in the Everyday Practical Electronics design by using modern components.

     

    https://www.slideshare.net/jplateado/earth-resistivity-meter-part-1a-robert-beck

     

    The block diagram is just about legible in the link, but the article gives a good background.

     

    We could do it now by making a DDS oscillator which can work at any frequency between 20 and 200 Hz (more range than commercial boxes offer). Then you need an amplifier able to manage +/- 25V out (not hard), a low noise diff amp and a low noise 24 bit ADC.

     

    A micro to drive it all and either a serial interface to a laptop or maybe a Pi if you prefer. (Laptops solve all the boring battery/screen/keyboard/box issues for you).

    No point in using wireless - because you have to have wires any way to make the system work..

     

    Sounds interesting, walking the dog yesterday I'd got as far as designing a system (in my head) with an autonomous moving probe but perhaps we should walk before running .........

     

    How much should the electronic box (excluding the laptop) cost ?

     

    MK

  • in reply to michaelkellett

    Hi Michael This all sounds very interesting and encouraging. I see you have found the original article, the update is also on slideshare somewhere. I haven’t really thought much about cost, but as you can see on the parts list, they give a ballpark of £48, but that was 1997. I think I would go with a Pi and 10” pi touchscreen. I don’t think programming in Python is that difficult. I did think of having a visual display where a grid was drawn on screen and filled in as work progressed, a bit like Fifty shades of grey. The moving probe bit has been done by R M Frobisher for their TAR-3 meter, but their offering costs £2986 currently. I’m a bit of an amateur when it comes to designing electronics, but I’ve built plenty of electronic bits in the past, mostly from magazine articles like this one. I also have a good bit of experience with the Raspberry Pi.
    Thank you for your ideas, all food for thought. Now to design.

    Ken

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  • in reply to michaelkellett

    Hi Michael This all sounds very interesting and encouraging. I see you have found the original article, the update is also on slideshare somewhere. I haven’t really thought much about cost, but as you can see on the parts list, they give a ballpark of £48, but that was 1997. I think I would go with a Pi and 10” pi touchscreen. I don’t think programming in Python is that difficult. I did think of having a visual display where a grid was drawn on screen and filled in as work progressed, a bit like Fifty shades of grey. The moving probe bit has been done by R M Frobisher for their TAR-3 meter, but their offering costs £2986 currently. I’m a bit of an amateur when it comes to designing electronics, but I’ve built plenty of electronic bits in the past, mostly from magazine articles like this one. I also have a good bit of experience with the Raspberry Pi.
    Thank you for your ideas, all food for thought. Now to design.

    Ken

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