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Max 1270 & ADC 0838 — Parallax Forums

Max 1270 & ADC 0838

Sutton MurraySutton Murray Posts: 88
edited 2007-10-01 17:01 in BASIC Stamp
Greetings all.

I am battling to find a good example to read all 8 channels from the Max 1270.
Please can someone help me with an example.

Question: Will the max 1270 have a better stability reading if compared against the ADC 0838? I have experimented with the 0838 and have a lot of problems with readings. Adding volts to one or more channels sometimes have effects on another channel. This is nun-sequential or what i refer to as nun stable.

Have any one used an 0838 in a large circuit, sampling all 8 channels with success. I would like to see such a circuit.

Comments

  • Sutton MurraySutton Murray Posts: 88
    edited 2007-09-26 14:50
    No reply on my post.

    The max is also sold by Parallax and are recommended for the Parallax PLC.

    Any help!!!
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-09-27 14:28
    have you looked at the following N7V article?

    http://www.parallax.com/dl/docs/cols/nv/vol5/col/nv105.pdf


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    Chris Savage
    Parallax Tech Support


    Post Edited (Chris Savage (Parallax)) : 9/27/2007 2:34:08 PM GMT
  • Sutton MurraySutton Murray Posts: 88
    edited 2007-09-29 08:52
    Chris, have seen this one before. Will have a better look at this, thanks
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-10-01 16:03
    the base material is there. You need only build off from that. I haven't yet had a need for such a chip so I have no example code for you. Sorry. =)

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    Chris Savage
    Parallax Tech Support
  • Sutton MurraySutton Murray Posts: 88
    edited 2007-10-01 16:42
    Chris

    Thanks for the link.

    In my last effort to solve my problem i have redesigned my board fitting a LTC1298. I had problems with this IC as well. All 3 chips 0838,1270 and the 1298 all gave me problems with unstable fluctuations on the channels. From your link i have found a added small diagram to reduce noise. My board still fitted with the LTC1298 i have added this noise filtering diagram and it helped, this stopped the fluctuations. My guess is that this will solve my problem on the 0838 and 1270 chips, am i correct? My problem seems to be noise interference. Can one work from a few basic rules when designing boards? Are added noise filters always needed on A to D converters?

    I do not have the necessary knowledge to understand what is wrong in my board designs when it comes to A to D converters.

    Please can you give me a few tips?

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    For in much wisdom is much grief, and he who increases knowledge increases sorrow." ~Ecclesiastes 1:18
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-10-01 17:01
    There are whole books written on how to avoid noise in PCB layouts and other board designs. Fact is there are a lot of variables involved here. I start at the power supply and work my way up. Ripple in the P/S is the first suspect in noise. Next to that are the way the inputs are wired and/or run on the PCB. Then there are always other component placement issues. But you will definitely need to do some research on the subject. Take care.

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    Chris Savage
    Parallax Tech Support
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