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Re: Off topic, conductivity and PH circuit

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  • jtsereyka
    Hi, My idea of robots is the planting and harvesting of food by an autonomous device or devices.The system I am planning to use is Hydroponics or Astroponics
    Message 1 of 7 , Feb 28, 2002
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      Hi,
      My idea of robots is the planting and harvesting of food by an autonomous
      device or devices.The system I am planning to use is Hydroponics or
      Astroponics as NASA refers to it. Before I can get to the really fun stuff I
      have
      to grow the crop using configurations easily handled by these yet to be
      designed Agslaves. I would like to build my own sensors (because of the
      high cost and the need for a set for each of many self contained pods) for
      the following environmental parameters.
      1. Conductivity meter as opposed to an ohm meter. (used to measure nutrient
      salt content in water)
      2. PH sensor/meter
      3. Humidity sensor/meter
      4. Dissolved oxygen sensor/meter (used to measure oxygen in water)
      5. carbon dioxide sensor/meter (used to measure CO in the air)
      Thank you for reading this post and if you have any suggestions I would
      sincerely appreciate a
      reply.
      Jimmy
    • Mark Medonis
      Well, I don t know about the other sensors but a conductivity meter and an ohm meter are pretty much the same thing. Conductivity in Siemens is the inverse of
      Message 2 of 7 , Mar 1, 2002
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        Well, I don't know about the other sensors but a conductivity meter and an
        ohm meter are pretty much the same thing. Conductivity in Siemens is the
        inverse of resistivity in Ohms, if I my foggy recollection of circuit stuff
        is correct. Ohms = 1/Siemens

        Mark Medonis

        > From: "jtsereyka" <jtsereyka@...>
        > Date: Thu, 28 Feb 2002 23:38:52 -0800
        > To: <SeattleRobotics@yahoogroups.com>
        > Subject: [SeattleRobotics] Re: Off topic, conductivity and PH circuit
        >
        >
        >
        > Hi,
        > My idea of robots is the planting and harvesting of food by an autonomous
        > device or devices.The system I am planning to use is Hydroponics or
        > Astroponics as NASA refers to it. Before I can get to the really fun stuff I
        > have
        > to grow the crop using configurations easily handled by these yet to be
        > designed Agslaves. I would like to build my own sensors (because of the
        > high cost and the need for a set for each of many self contained pods) for
        > the following environmental parameters.
        > 1. Conductivity meter as opposed to an ohm meter. (used to measure nutrient
        > salt content in water)
        > 2. PH sensor/meter
        > 3. Humidity sensor/meter
        > 4. Dissolved oxygen sensor/meter (used to measure oxygen in water)
        > 5. carbon dioxide sensor/meter (used to measure CO in the air)
        > Thank you for reading this post and if you have any suggestions I would
        > sincerely appreciate a
        > reply.
        > Jimmy
        >
        >
        >
        >
        > Visit the SRS Website at http://www.seattlerobotics.org
        >
        > To unsubscribe from this group, send an email to:
        > SeattleRobotics-unsubscribe@yahoogroups.com
        >
        >
        > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        >
        >
      • jtsereyka
        In the theoretical sense your probably correct, however I m told that a meter measuring conductivity in a saline solution usees an ac sensing circuit to avoid
        Message 3 of 7 , Mar 1, 2002
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          In the theoretical sense your probably correct, however I'm told that a
          meter
          measuring conductivity in a saline solution usees an ac sensing circuit to
          avoid plating out on the probes. Since the standard meter uses a dc current
          to measure resistance.
          Thanks, Jimmy
          ----- Original Message -----
          From: "Mark Medonis" <mark@...>
          To: <SeattleRobotics@yahoogroups.com>
          Sent: Friday, March 01, 2002 7:49 AM
          Subject: Re: [SeattleRobotics] Re: Off topic, conductivity and PH circuit


          > Well, I don't know about the other sensors but a conductivity meter and an
          > ohm meter are pretty much the same thing. Conductivity in Siemens is the
          > inverse of resistivity in Ohms, if I my foggy recollection of circuit
          stuff
          > is correct. Ohms = 1/Siemens
          >
          > Mark Medonis
          >
          > > From: "jtsereyka" <jtsereyka@...>
          > > Date: Thu, 28 Feb 2002 23:38:52 -0800
          > > To: <SeattleRobotics@yahoogroups.com>
          > > Subject: [SeattleRobotics] Re: Off topic, conductivity and PH circuit
          > >
          > >
          > >
          > > Hi,
          > > My idea of robots is the planting and harvesting of food by an
          autonomous
          > > device or devices.The system I am planning to use is Hydroponics or
          > > Astroponics as NASA refers to it. Before I can get to the really fun
          stuff I
          > > have
          > > to grow the crop using configurations easily handled by these yet to be
          > > designed Agslaves. I would like to build my own sensors (because of the
          > > high cost and the need for a set for each of many self contained pods)
          for
          > > the following environmental parameters.
          > > 1. Conductivity meter as opposed to an ohm meter. (used to measure
          nutrient
          > > salt content in water)
          > > 2. PH sensor/meter
          > > 3. Humidity sensor/meter
          > > 4. Dissolved oxygen sensor/meter (used to measure oxygen in water)
          > > 5. carbon dioxide sensor/meter (used to measure CO in the air)
          > > Thank you for reading this post and if you have any suggestions I would
          > > sincerely appreciate a
          > > reply.
          > > Jimmy
          > >
          > >
          > >
          > >
          > > Visit the SRS Website at http://www.seattlerobotics.org
          > >
          > > To unsubscribe from this group, send an email to:
          > > SeattleRobotics-unsubscribe@yahoogroups.com
          > >
          > >
          > > Your use of Yahoo! Groups is subject to
          http://docs.yahoo.com/info/terms/
          > >
          > >
          >
          >
          > Visit the SRS Website at http://www.seattlerobotics.org
          >
          > To unsubscribe from this group, send an email to:
          > SeattleRobotics-unsubscribe@yahoogroups.com
          >
          >
          > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
          >
          >
        • Bruce
          Jimmy: Well, I can also give you some help (maybe....) Overall, there are some hydroponics websites out there that may be able to give you a hand here.
          Message 4 of 7 , Mar 1, 2002
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            Jimmy:

            Well, I can also give you some help (maybe....)

            Overall, there are some hydroponics websites out there that may be able
            to give you a hand here. Overall, though, home growing these sensors
            may be a problem.

            PH sensor/meter: There are cheap (approximately 20 dollar) sensors avaliable for these. You may also be able to rig something with a color indicator and a crude filter spectrometer working in the visible. A pH probe, however, is typically an electrochemical cell with a special membrane that allows the H ions to pass to one electrode. The membrane is a special glass.

            Humidity sensor/meter: Newark sells a pretty good one that readily interfaces to a PIC, etc. Probably not too expensive.

            Dissolved oxygen sensor/meter: Well, your car uses an oxygen sensor, but they ain't cheap if my recollection is corrrect. Here two, the sensor is designed for gas, so you'll have to come up with some kind of membrane that will allow gas to pass but not oxygen. You may be able to do this with pure polyethylene - it's a staright chain hydrocarbon - very non-polar, so it's hyrophobic (water hating) so a relatively non-polar molecule like oxygen may be able to pass pretty readily. Also you'll have to figure out what the output is like (viz., calibrate).


            carbon dioxide sensor/meter (used to measure CO in the air): I trust you mean CO2, not CO, which is carbon monoxide. For what this is worth, the only instrumental method of doing this that I am aware of uses a filter infrared spectrometer, set for the highly absorbing band at about 2200 wavenumbers (roughly 5 microns of light). again, noty impossible to home grow, but not easy (or cheap) either.

            Anyway, I'm not trying to be discouraging, but these are difficult to
            simply make in one's workshop! One avenue you may try is Ebay - believe
            it or not, I see a fair amount of scientific equipment out there - some
            of it worth a lot more than what the opening bid is (for example, I saw
            a module for an infrared spectrometer that retails for about 20,000.
            The detector alone, if workable, could easily go for 500.00 on the
            used market I would guess).

            Regards,
            Bruce
            PS: I'm an analytical chemist by trade.


            Mark Medonis wrote:

            >Well, I don't know about the other sensors but a conductivity meter and an
            >ohm meter are pretty much the same thing. Conductivity in Siemens is the
            >inverse of resistivity in Ohms, if I my foggy recollection of circuit stuff
            >is correct. Ohms = 1/Siemens
            >
            >Mark Medonis
            >
            >>From: "jtsereyka" <jtsereyka@...>
            >>Date: Thu, 28 Feb 2002 23:38:52 -0800
            >>To: <SeattleRobotics@yahoogroups.com>
            >>Subject: [SeattleRobotics] Re: Off topic, conductivity and PH circuit
            >>
            >>
            >>
            >>Hi,
            >>My idea of robots is the planting and harvesting of food by an autonomous
            >>device or devices.The system I am planning to use is Hydroponics or
            >>Astroponics as NASA refers to it. Before I can get to the really fun stuff I
            >>have
            >>to grow the crop using configurations easily handled by these yet to be
            >>designed Agslaves. I would like to build my own sensors (because of the
            >>high cost and the need for a set for each of many self contained pods) for
            >>the following environmental parameters.
            >>1. Conductivity meter as opposed to an ohm meter. (used to measure nutrient
            >>salt content in water)
            >>2. PH sensor/meter
            >>3. Humidity sensor/meter
            >>4. Dissolved oxygen sensor/meter (used to measure oxygen in water)
            >>5. carbon dioxide sensor/meter (used to measure CO in the air)
            >>Thank you for reading this post and if you have any suggestions I would
            >>sincerely appreciate a
            >>reply.
            >>Jimmy
            >>
            >>
            >>
            >>
            >>Visit the SRS Website at http://www.seattlerobotics.org
            >>
            >>To unsubscribe from this group, send an email to:
            >>SeattleRobotics-unsubscribe@yahoogroups.com
            >>
            >>
            >>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
            >>
            >>
            >
            >
            >Visit the SRS Website at http://www.seattlerobotics.org
            >
            >To unsubscribe from this group, send an email to:
            >SeattleRobotics-unsubscribe@yahoogroups.com
            >
            >
            >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
            >
            >
            >



            [Non-text portions of this message have been removed]
          • Bruce
            Hi Eric: well, you got me curious, and so I hit Google with it - for what s it s worth, what appears to have happened is that they ve managed to shrink the IR
            Message 5 of 7 , Mar 7, 2002
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              Hi Eric:

              well, you got me curious, and so I hit Google with it - for what's it's
              worth, what appears to have happened is that they've managed to shrink
              the IR analyzer to a small, transistor like enclosure, so it's all
              self-contained. So, while, the price has come way down, they still are
              using IR based technology. The fact that the HS paid 100 - 200 dollars
              suggests the sensor itself is in the 0 - 100 dollar range, although TI
              may be reducing the margin to the bare minimum so they sell their
              calculators (actually, my kid played with these - I was pretty impressed
              really, since they could play with the data when they got home.).

              thanks,
              Bruce

              Eric Stokely wrote:

              >snip
              ><<carbon dioxide sensor/meter (used to measure CO in the air): I trust
              >you mean CO2, not CO, which is carbon monoxide. For what this is worth,
              >the only instrumental method of doing this that I am aware of uses a
              >filter infrared spectrometer, set for the highly absorbing band at about
              >2200 wavenumbers (roughly 5 microns of light). again, noty impossible
              >to home grow, but not easy (or cheap) either.
              > >>
              >
              >I was simply enjoying reading the comments. Now I have to make one of my
              >own
              >
              >While I was a HS teacher in California we used a CBL (Calculator Based
              >Laboratory) from TI. It was based on the 8x series of calculators.
              >Anyway they had a CO2 sensor that was used in simple "put a cricket and
              >a plant in a sealed case and watch the CO2 levels over time" types of
              >experiments. Since it was for a public school it wasn't very expensive
              >but it also wasn't dirt cheap (if memory serves between 100-200
              >dollars). Now that I think of it I have no idea how it actually worked.
              >I always assumed a CO2 selective membrane.
              >Have fun
              >
              >Eric Stokely
              >
              >
              >[Non-text portions of this message have been removed]
              >
              >
              >Visit the SRS Website at http://www.seattlerobotics.org
              >
              >To unsubscribe from this group, send an email to:
              >SeattleRobotics-unsubscribe@yahoogroups.com
              >
              >
              >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
              >
              >
              >
            • Ravindra Agrawal
              You may also want to look at http://www.fisinc.co.jp - they have CO2 sensor based on metaloxide semiconductor technology. I just read about them, but haven t
              Message 6 of 7 , Mar 7, 2002
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                You may also want to look at http://www.fisinc.co.jp - they have CO2 sensor
                based on metaloxide semiconductor technology. I just read about them, but
                haven't used them.


                >From: Bruce <blerner624@...>
                >To: Eric Stokely <estokely@...>, SeattleRobotics@yahoogroups.com
                >Subject: Re: [SeattleRobotics] Re: Off topic, conductivity and PH circuit
                >Date: Thu, 07 Mar 2002 07:18:26 -0500
                >
                >Hi Eric:
                >
                >well, you got me curious, and so I hit Google with it - for what's it's
                >worth, what appears to have happened is that they've managed to shrink
                >the IR analyzer to a small, transistor like enclosure, so it's all
                >self-contained. So, while, the price has come way down, they still are
                >using IR based technology. The fact that the HS paid 100 - 200 dollars
                >suggests the sensor itself is in the 0 - 100 dollar range, although TI
                >may be reducing the margin to the bare minimum so they sell their
                >calculators (actually, my kid played with these - I was pretty impressed
                >really, since they could play with the data when they got home.).
                >
                >thanks,
                >Bruce
                >
                >Eric Stokely wrote:
                >
                > >snip
                > ><<carbon dioxide sensor/meter (used to measure CO in the air): I trust
                > >you mean CO2, not CO, which is carbon monoxide. For what this is worth,
                > >the only instrumental method of doing this that I am aware of uses a
                > >filter infrared spectrometer, set for the highly absorbing band at about
                > >2200 wavenumbers (roughly 5 microns of light). again, noty impossible
                > >to home grow, but not easy (or cheap) either.
                > > >>
                > >
                > >I was simply enjoying reading the comments. Now I have to make one of my
                > >own
                > >
                > >While I was a HS teacher in California we used a CBL (Calculator Based
                > >Laboratory) from TI. It was based on the 8x series of calculators.
                > >Anyway they had a CO2 sensor that was used in simple "put a cricket and
                > >a plant in a sealed case and watch the CO2 levels over time" types of
                > >experiments. Since it was for a public school it wasn't very expensive
                > >but it also wasn't dirt cheap (if memory serves between 100-200
                > >dollars). Now that I think of it I have no idea how it actually worked.
                > >I always assumed a CO2 selective membrane.
                > >Have fun
                > >
                > >Eric Stokely
                > >
                > >
                > >[Non-text portions of this message have been removed]
                > >
                > >
                > >Visit the SRS Website at http://www.seattlerobotics.org
                > >
                > >To unsubscribe from this group, send an email to:
                > >SeattleRobotics-unsubscribe@yahoogroups.com
                > >
                > >
                > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                > >
                > >
                > >
                >
                >
                >
                >Visit the SRS Website at http://www.seattlerobotics.org
                >
                >To unsubscribe from this group, send an email to:
                >SeattleRobotics-unsubscribe@yahoogroups.com
                >
                >
                >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                >
                >




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              • Eric Stokely
                snip
                Message 7 of 7 , Mar 5, 2003
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                  snip
                  <<carbon dioxide sensor/meter (used to measure CO in the air): I trust
                  you mean CO2, not CO, which is carbon monoxide. For what this is worth,
                  the only instrumental method of doing this that I am aware of uses a
                  filter infrared spectrometer, set for the highly absorbing band at about
                  2200 wavenumbers (roughly 5 microns of light). again, noty impossible
                  to home grow, but not easy (or cheap) either.
                  >>

                  I was simply enjoying reading the comments. Now I have to make one of my
                  own

                  While I was a HS teacher in California we used a CBL (Calculator Based
                  Laboratory) from TI. It was based on the 8x series of calculators.
                  Anyway they had a CO2 sensor that was used in simple "put a cricket and
                  a plant in a sealed case and watch the CO2 levels over time" types of
                  experiments. Since it was for a public school it wasn't very expensive
                  but it also wasn't dirt cheap (if memory serves between 100-200
                  dollars). Now that I think of it I have no idea how it actually worked.
                  I always assumed a CO2 selective membrane.
                  Have fun

                  Eric Stokely


                  [Non-text portions of this message have been removed]
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