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  • #1

    PI1 article

    I've just posted a prelim (very) version of the construction article for the PI1 project. It currently covers operation and circuit description, and lacks artwork. However, with a copy of the schematic, it's easy to follow (IMO!).

    Feedback is welcomed. I would like to get the artwork done for what I've written so far, before plowing ahead.

    - Carl
    Tags: None
  • #2
    Re

    Thanks Carl

    Comment

    • #3
      Re: PI1 article

      Thank you for your work.
      It is very helpful for me

      sorry for my bad english....

      Andy

      Comment

      • #4
        Re: PI1 article

        Very good information on.
        Just one little remarq: on the receiver back end paragraf you speak about C28 i think it's C20? What do you think of this?
        Have you make a prototype?
        Have you take some diagram of the different signal from the design?
        I want to design a PI with a microcontroler type PIC16F876 to drive the timing : pulse, sample, sound.
        But i never built any PI detector , my univerty experience (BTS electrotechnique 1980) and info about PI by the WEB was all that i know and I found a lot of information about this but very few reel information about the curve of the decay signal from the coil with different material and different size of same material.( copie of scope screen)
        I think that i need to make my own experience ( certainely with your open design).
        I'm afflicted to see that it's very difficult to have this information: the web and forum is a very good thing to exchange this type of information .....
        Many thanks CARL continue...
        If you want some help ask me...
        BYE BYE
        Philippe

        Comment

        • #5
          Re: PI1 article

          >Just one little remarq: on the receiver back end paragraf you speak about C28 i think it's C20? What do you think of this?

          Yup, you're right... that's why I posted it for review!

          >Have you make a prototype?

          The proto is still on the bench getting tweaked, I will be packaging it over the holidays and taking it out for some testing.

          >Have you take some diagram of the different signal from the design?

          Working on that.

          >I want to design a PI with a microcontroler type PIC16F876 to drive the timing : pulse, sample, sound.

          Phase 2, maybe. Robert has the lead on this using the ADuC, and I'm going to try to devote some time to it over the holidays.

          >But i never built any PI detector , my univerty experience (BTS electrotechnique 1980) and info about PI by the WEB was all that i know and I found a lot of information about this but very few reel information about the curve of the decay signal from the coil with different material and different size of same material.( copie of scope screen)

          >I think that i need to make my own experience ( certainely with your open design).

          Welcome to the club! That's exactly what I intended this project for.

          - Carl

          Comment

          • #6
            Re: PI1 article

            There are different ways of using a microcontroller in a PI that have different levels of difficulty.

            1. The easiest would be to just have the microcontroller take over the timing functions. The micro does not have much work to do and the program is small and should be easy to get running. This would eliminate the timing chips from the design.

            2. The next level of difficulty would be to have the microcontroller sample the signal at the output of the integrator (IC8a). If you use 2 ADC channels you can sample from both sides of C19 and get both motion and non-motion signals. The microcontroller does not have to be very fast because sampling at about 100 Hz would be enough. Then the microcontroller could add the threshold and chop the signal to make the audio output. The microcontroller would have to do a lot more work than the first case and there is more software to write, but it still does not have to do much math. This would eliminate all the parts from IC8b to IC9.

            3. The next level is to sample before the integrator eliminating IC8a. This is much more work because now the sampling has to be done at the pulse rate or higher. And now there is a lot of math to do to filter the samples. An advantage of doing this is that you can take extra samples at different delay times to try to identify the target.

            I am working on this third case but case 2 is a lot less work for only a small difference in the amount of analog parts. And I am not certain that I will be able to get the same performance possible from case 2. I hope that I can, but I will not know for sure until after I do all the work.

            Robert

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            • #7
              Re: PI1 article

              I will also work on case 3. Case 1 has been done in some of the other projects (GoldPic & Stuart), and case 2 is how Tesoro does the SandShark. If case 3 performs poorly, then back off to 2.

              - Carl

              Comment

              • #8
                Re: PI1 article

                Nice job Carl
                The project is shaping up very nicely, and you have done an excellent job. When finalized this may well become the primer for the DIY PI builder. I had hoped to be able to contribute more than I have been able to, but other commitments have virtually eliminated my bench time.
                Hope You and Yours have a Great Holiday Season.
                Russ

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