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Adc0831 — Parallax Forums

Adc0831

MacGeek117MacGeek117 Posts: 747
edited 2005-10-25 22:58 in General Discussion
I can't seem to find a usable schematic for the ADC0831. Could someone please give me or point me in the direction of a good schematic?
RoboGeek

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Comments

  • Jon WilliamsJon Williams Posts: 6,491
    edited 2005-10-22 02:55
    Define "usable"? And what mode? We have lots of ADC0831 examples -- you can find them in "What's A Microcontroller?" and in "StampWorks" among other places.

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    Jon Williams
    Applications Engineer, Parallax
  • KenMKenM Posts: 657
    edited 2005-10-22 03:32
    Robo,

    Try this

    http://www.parallax.com/dl/docs/books/sw/exp/sw27.pdf

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    Ken
  • MacGeek117MacGeek117 Posts: 747
    edited 2005-10-22 23:20
    THANK YOU, KEN! I did not even think to look at StampWorks. Jon, I'm sorry I was not more specific, I was looking for a practical schematic, not a theoretical one.
    RoboGeek

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    There are 10 kinds of people in the world,

    those that know binary and those that don't.
    Formerly bugg.
    www.goldmine-elec.com
    www.parallax.com
    www.expresspcb.com
    www.startrek.com
    ·
  • FlyingFishFingerFlyingFishFinger Posts: 461
    edited 2005-10-23 01:29
    For either the ADC0831 or theLTC1298, is the only measurement range 0-5V or can I measure 0-12V?
    Rafael
  • KenMKenM Posts: 657
    edited 2005-10-23 07:13
    For the 0831 you are limited to 5v. One way to overcome this is for your 0831 to sample a fraction of the 12 volts. That fraction would come from a voltage divider.

    For the 1298 you are limited to 9v when using a 9v source, and the same limitation can be overcome with a voltage divider.

    If a voltage divider is the way you decide to go, I would run either ADC off 5v to keep the power supply topology simple. Also, I would make sure the divider current is at least 10 times the current required by the ADC, 1 mA should be plenty.




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    Ken
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  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-23 17:39
    Hello,

    ·· I recently checked out a link posted by a forum member which showed where a guy used a very interesting method of measuring 0-15V with a BASIC Stamp and a 5V ADC.· He piped the voltage (Via resistor) into an Optocoupler, then read the output into the ADC.· Not sure about linearity or accuracy, but it seemed to work well in the application which was measuring the voltage levels of Car Batteries in-system.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • BlueZX#BlueZX# Posts: 14
    edited 2005-10-24 18:17
    I would be "VERY" interested in that link Chris, this is excatly what I was lookin for/going to try as well.

    Hopefully this will cut some time out of trial and error...
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-24 19:12
    Hello,

    ·· I saved the link at home, so I will post it in a couple of hours for you.· =)

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • MacGeek117MacGeek117 Posts: 747
    edited 2005-10-24 19:31
    Thank you for all your help, guys. I have a temperature probe working, but I would like to convert the voltage to degrees C. Here are some values: 9 degrees F, 0.431V; 68 degrees F, 2.215V.
    RoboGeek

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    There are 10 kinds of people in the world,

    those that know binary and those that don't.
    Formerly bugg.
    www.goldmine-elec.com
    www.parallax.com
    www.expresspcb.com
    www.startrek.com


    Post Edited (RoboGeek) : 10/24/2005 7:35:10 PM GMT
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2005-10-24 19:40
    Does you sensor have millivots/degree specification?

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    Jon Williams
    Applications Engineer, Parallax
  • MacGeek117MacGeek117 Posts: 747
    edited 2005-10-24 19:50
    Electronics Goldmine says: Small thermistor Type A170. Cool resistance approx. 1.5K ohms. Hot resistance approx. 25 ohms.
    I'm using it in a voltage divider like this:
    Vdd--thermistor--ADC input pin--1k resistor--Gnd.
    RoboGeek

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    There are 10 kinds of people in the world,

    those that know binary and those that don't.
    Formerly bugg.
    www.goldmine-elec.com
    www.parallax.com
    www.expresspcb.com
    www.startrek.com
    ·
  • MacGeek117MacGeek117 Posts: 747
    edited 2005-10-24 21:57
    I also forgot to say that the temp probe is a thermistor connected to the ADC0831.
    RoboGeek

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    There are 10 kinds of people in the world,

    those that know binary and those that don't.
    Formerly bugg.
    www.goldmine-elec.com
    www.parallax.com
    www.expresspcb.com
    www.startrek.com
    ·
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-24 22:19
    OFF-TOPIC, but in response to an earlier request...

    The car battery voltage monitor can be found at the following link:
    http://genki.home.ionet.net/BattMon/BattMonArticle.html

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2005-10-24 22:20
    You may need to do some emperical testing; you could use an ice-bath (add salt to the water to lower the temperature), room temperature, and then boiling water (if your sensor will tolerate that). From there you should be able to derive direct calculations for C or F.

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    Jon Williams
    Applications Engineer, Parallax
  • MacGeek117MacGeek117 Posts: 747
    edited 2005-10-25 12:39
    Thanks, Jon. I was hoping that there would be some earlier tread that asked the same question, but search doesn't help either. BTW, what happened?

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    There are 10 kinds of people in the world,

    those that know binary and those that don't.
    Formerly bugg.
    www.goldmine-elec.com
    www.parallax.com
    www.expresspcb.com
    www.startrek.com
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    bmp
    untitled2.bmp
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  • KenMKenM Posts: 657
    edited 2005-10-25 14:11
    RoboGeek said...
    ·BTW, what happened?
    Halloween is approaching.....that is Jon's costume I am sure.· Probably had one of his "makeup artists" paint him. Looks good !

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    Ken
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2005-10-25 22:58
    Actually, I did that make-up myself (another one of my interests) for a Halloween convention that the Parallax EFX team attended. The "zombie bite" on the cheek is created with Wolf Brothers silicone and all the rest good ol' Ben Nye make-up -- with a little Bloody Mary blood.

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    Jon Williams
    Applications Engineer, Parallax
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