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  • Long temp sensors

    Hi. I bought 2 of the temp sensors off the site to test with and they work accurately. What I'd like to do now is either buy new sensors or lengthen the ones I have. What's the best way to do this?

    I'm about finished building a solar water heater and I want to run the sensors from the panel outside into my computer in the house.

    I found one of these bad boys through a Google search LINKY.



    Could I just extend the 3 leads with cat5 cable or something similar?
    2001 SS Camaro carputer | My solar dish project/

  • #2
    Don't quote me (Or someone else might be able to confirm), but I think that if you make the leads longer, the reading gets skewed, so you could probably lengthen it, but you would need to recalibrate the readings to suit.

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    • #3
      Why would you use that instead of the ones you have bought from us? Ours have a larger response range and work the same otherwise. Just extend the leads.
      Fusion Brain Version 6 Released!
      1.9in x 2.9in -- 47mm x 73mm
      30 Digital Outputs -- Directly drive a relay
      15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
      Buy now in the MP3Car.com Store

      Comment


      • #4
        Originally posted by Chester View Post
        Don't quote me (Or someone else might be able to confirm), but I think that if you make the leads longer, the reading gets skewed, so you could probably lengthen it, but you would need to recalibrate the readings to suit.
        This is correct. The added length of wire will scew the readings. But it should be a constant skew so you can correct for it in software.
        Fusion Brain Version 6 Released!
        1.9in x 2.9in -- 47mm x 73mm
        30 Digital Outputs -- Directly drive a relay
        15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
        Buy now in the MP3Car.com Store

        Comment


        • #5
          Originally posted by 2k1Toaster View Post
          Why would you use that instead of the ones you have bought from us? Ours have a larger response range and work the same otherwise. Just extend the leads.
          I wasn't sure if I could simply extend the leads or not and have things still work correctly.
          2001 SS Camaro carputer | My solar dish project/

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          • #6
            Temp sensors are usually low impedance (eg LM335; typically under than 1 Ohm) hence lead length shouldn't be a problem if your voltage measuring circuit is high impedance and the supply current isn't causing a major voltage drop.

            Comment


            • #7
              Good deal. I got the sensors and I made a 30' cable. Quick side note: where can I buy the little black things that connect to the brain? What I got didn't work so well. Anyway I have my 30' cable and I used the "Temp �C = 100*(reading in V) - 50" formula that they recommend.

              The reported temp comes back within a few degrees below the actual temp and it also seems to swing roughly 5 degrees F. It has me rather puzzled.

              I'll make a short cable tomorrow and see if that clears up the issues.
              2001 SS Camaro carputer | My solar dish project/

              Comment


              • #8
                Originally posted by scotty562 View Post
                Good deal. I got the sensors and I made a 30' cable. Quick side note: where can I buy the little black things that connect to the brain? What I got didn't work so well. Anyway I have my 30' cable and I used the "Temp �C = 100*(reading in V) - 50" formula that they recommend.

                The reported temp comes back within a few degrees below the actual temp and it also seems to swing roughly 5 degrees F. It has me rather puzzled.

                I'll make a short cable tomorrow and see if that clears up the issues.
                Remember an antenna is just a wire. You are making a 30ft antenna and carrying a relatively small signal over it. So even lights will introduce a 60Hz (or 50Hz if you are in Europe) noise. It will not be as accurate. Also the formula will need to be adjusted a little bit because the signal will deteriorate a little bit.

                Version 5 will fix all of these issues.
                Fusion Brain Version 6 Released!
                1.9in x 2.9in -- 47mm x 73mm
                30 Digital Outputs -- Directly drive a relay
                15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
                Buy now in the MP3Car.com Store

                Comment


                • #9
                  Try small caps across the line...

                  I'd try across the supply at the sensor end, and across the signal (to GND) at the brain end.

                  Probably a greencap (ceramic) or similar of .001uF to 0.1uF (1nF-100nF).

                  STOP PRESS - suggest 1nF for the output to gnd (at the brain end) - I just read the specs....
                  See page 17 if still a problem. Also p10. (Of the linked adafruit pdf datasheet.)

                  Comment


                  • #10
                    Our sensors already include capacitors at the sensor.
                    Fusion Brain Version 6 Released!
                    1.9in x 2.9in -- 47mm x 73mm
                    30 Digital Outputs -- Directly drive a relay
                    15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
                    Buy now in the MP3Car.com Store

                    Comment


                    • #11
                      Cool - if it's for the power only.....

                      Do you include one for the output? If so, what value?
                      The specs state "up to 10nF without oscillation", hence I figured 1nF should be okay (allowing for some cable capacitance etc).

                      If on the output, can it be removed (since we want it at the FB end)?

                      Comment


                      • #12
                        Originally posted by 2k1Toaster View Post
                        Remember an antenna is just a wire. You are making a 30ft antenna and carrying a relatively small signal over it. So even lights will introduce a 60Hz (or 50Hz if you are in Europe) noise. It will not be as accurate. Also the formula will need to be adjusted a little bit because the signal will deteriorate a little bit.

                        Version 5 will fix all of these issues.
                        Ahh. Is there anyway to compensate for that noise it's picking up? I tried adjusting the formula for a few hours last night and I couldn't' get anything that was consistent. The closest thing I could get was just changing the - 50 to - 49.

                        Originally posted by OldSpark

                        Try small caps across the line...

                        I'd try across the supply at the sensor end, and across the signal (to GND) at the brain end.

                        Probably a greencap (ceramic) or similar of .001uF to 0.1uF (1nF-100nF).

                        STOP PRESS - suggest 1nF for the output to gnd (at the brain end) - I just read the specs....
                        See page 17 if still a problem. Also p10. (Of the linked adafruit pdf datasheet.)
                        Ahh good find. This looks promising, and answers my question. Now to find one of those caps.

                        Edit:
                        This looks like a winner: LINKY

                        Originally posted by 2k1Toaster
                        Our sensors already include capacitors at the sensor.
                        I was wondering what that was. Since this project is mostly a learning experience I thought it'd be fun to build my own cable .
                        2001 SS Camaro carputer | My solar dish project/

                        Comment


                        • #13
                          Have you tried increasing the number of samples for averaging to smooth out the swings? How fast a response do you need for the temperature changes?

                          I've been getting the connectors from here: http://www.nanosys1.com/cables---ada...-housings.html

                          Version 5?!!

                          Comment


                          • #14
                            Originally posted by ACCLR8N View Post
                            Have you tried increasing the number of samples for averaging to smooth out the swings? How fast a response do you need for the temperature changes?

                            I've been getting the connectors from here: http://www.nanosys1.com/cables---ada...-housings.html

                            Version 5?!!
                            That's what I forgot in my reply hehe. Version 5 sounds very exciting. I only need an update every 15 minutes so I can make the sample size really high. I'll give that a shot while I'm waiting on the caps to get here.

                            Is this the one you are using? I didn't see any 3 pin. http://www.nanosys1.com/con-hdr-hsng-4x1-bk.html

                            Just found this one http://www.pololu.com/catalog/product/1013. Thanks!

                            I just tried changing the "history to keep" from 15 to 100 and it works perfectly. This will actually work just fine for what I'm doing. The caps can only help now .
                            2001 SS Camaro carputer | My solar dish project/

                            Comment


                            • #15
                              I don't see why those wouldn't work and they are cheaper. Nano does have the 3 and 2 pin housings, but they show pictures of 10 pin. You have to buy the crimps as well.

                              Glad the averaging worked out.

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