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Thread: Long temp sensors

  1. #11
    Raw Wave
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    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)?

  2. #12
    Variable Bitrate
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    Quote 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.

    Quote 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

    Quote 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 .

  3. #13
    Constant Bitrate ACCLR8N's Avatar
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    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?!!

  4. #14
    Variable Bitrate
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    Quote 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 .

  5. #15
    Constant Bitrate ACCLR8N's Avatar
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    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.

  6. #16
    Fusion Brain Creator
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    Just to wrap this up, long cables pick up noise. Turning up the averaging works as a real rudimentary solution since the noise is mostly random.

  7. #17
    Raw Wave
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    Just curious - were capacitors tried? (IE - at the FB end to REMOVE the noise.)

    Averaging should be a last resort.
    [ Signal recovery should only be used where necessary - like 76dB Noise to Signal ratios (not SN!) LOL. ]

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