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Surf PI 1.2 calibration first run

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  • #1

    Surf PI 1.2 calibration first run

    Hi everyone,

    I soldered my kit a couple of days ago. Made a testcoil, etc.

    After spending quite some time adjusting the delay and offset, i manage to make it beep when hovering metal over the coil.

    Problem: 10 cm seems to be the maximum range that i get (hovering my
    Cellphone), and a couple of cm for a coin. So i have a calibration problem.

    I have to set the offset to around -2V to make it work as mentioned above. Setting it to 0V (or very close to it) doesn't yield beeps when hovering metal above it, no mather how i adjust the other POTS. What does this indicate?

    I made two coils, one with 0.5mm enamel wire and one with 0.4mm phone cable (using a coil calculator to het around 350uH). Both give more or less the same result. I don't think it's the coil.

    I use a 18650 power pack (8000 mAh, 7.4V), is the voltage sufficiently high)?

    I also get a lot of noise through the speakers, even when calibrated to the best of my ability.

    I don't have a oscilloscope, yet. I'm not an Electronics expert, but know how to program microcontroller, use MOSFETs, etc. Mostly DIY experience and by reading.

    I will make a video of my setup/problem later on.

    If someone has experience or ideas, please reply.

    Links to articles, manuals, datasheets,... Are also more than welcome.
    Tags: None
  • #2
    Originally posted by Hendrik View Post
    I use a 18650 power pack (8000 mAh, 7.4V), is the voltage sufficiently high)?
    The power pack voltage is too low. The Surf-PI is designed to run from 12V, but some people have been using 9V (sometimes with problems though).

    Comment

    • #3
      Originally posted by Qiaozhi View Post
      The power pack voltage is too low. The Surf-PI is designed to run from 12V, but some people have been using 9V (sometimes with problems though).
      Awesome. I've got 2 of those packs, i'll put them in series. Is 14-15V okay, or to high?

      Btw, is there a datasheet somewhere of the Surf PI 1.2? I couldn't find the specifications (voltage etc.)

      Comment

      • #4
        Originally posted by Hendrik View Post
        Awesome. I've got 2 of those packs, i'll put them in series. Is 14-15V okay, or to high?

        Btw, is there a datasheet somewhere of the Surf PI 1.2? I couldn't find the specifications (voltage etc.)
        The ICL7660 has an maximum supply voltage of 10.5V; but if you have an ICL7660A fitted, it can go up to 12V. That's probably the reason why some people are running the Surf-PI at 9V. Alternatively you could replace it with an LT1054 which can handle 15V, and is pin compatible.

        The supply voltages are shown on the schematic.

        Comment

        • #5
          Originally posted by Qiaozhi View Post
          The ICL7660 has an maximum supply voltage of 10.5V; but if you have an ICL7660A fitted, it can go up to 12V. That's probably the reason why some people are running the Surf-PI at 9V. Alternatively you could replace it with an LT1054 which can handle 15V, and is pin compatible.

          The supply voltages are shown on the schematic.
          However on the Surf Schematic, it shows that the 7660 Supply Voltage comes from the 5 Volt Regulated Supply.
          So using a 9 volt battery, 12 volts or 15 Volts does not matter.

          Comment

          • #6
            Originally posted by chemelec View Post
            However on the Surf Schematic, it shows that the 7660 Supply Voltage comes from the 5 Volt Regulated Supply.
            So using a 9 volt battery, 12 volts or 15 Volts does not matter.
            Oh yes ... silly me! I was replying from memory, which was clearly in error.

            In that case, a 15V supply should be ok.

            Comment

            • #7
              Probably the reason some guys use a 9 Volt battery is just for its Small Size.
              But those batteries are not good for High Current draws, so they will get Pulled Down in voltage when in operation.

              Comment

              • #8
                So my 7.4V 18650 battery pack should work? Or is it still advisable to use something with a higher potential?
                Btw, I won't be able to try another battery for a couple of days.

                Comment

                • #9
                  Originally posted by Hendrik View Post
                  So my 7.4V 18650 battery pack should work? Or is it still advisable to use something with a higher potential?
                  Btw, I won't be able to try another battery for a couple of days.
                  Since the transmit circuit runs directly from the battery, the energy in the coil will be lower at 7.4V than at 12V.
                  Last edited by Qiaozhi; 10-26-2015, 07:53 PM.

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                  • #10
                    Okay, so I tried the two battery packs in series. So 16ish V. With the offset set to 0V, I can can get it to sense metal at 40cm of distance, large objects though. Coins only 20cm or so. So now it's down to optimizing the coil.

                    How do I measure the inductance of my coil?

                    Comment

                    • #11
                      Originally posted by Hendrik View Post
                      Okay, so I tried the two battery packs in series. So 16ish V. With the offset set to 0V, I can can get it to sense metal at 40cm of distance, large objects though. Coins only 20cm or so. So now it's down to optimizing the coil.

                      How do I measure the inductance of my coil?
                      Buy or Borrow an Inductance Meter.

                      Comment

                      • #12
                        Ok thanks!

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