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Cheapest temp sensor and output relay circuit for PC

Discussion in 'Beginner Electronics' started by James, Apr 3, 2004.

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  1. James

    James Guest

    Anyone know what the cheapest way to get two temp sensors to report to a PC,
    with a single output to power a relay.

    Years ago there seems to have been loads of low cost boards, but nothing
    around now.

    Can anyone point me in the right direction?
  2. SQLit

    SQLit Guest

    Try Black Box
  3. James

    James Guest

    Any chance of a web link? A google search for "black box" is not helpful!
  4. scada

    scada Guest

    See the DI-194RS. This is a 10 bit A to D converter. Even
    comes with software all for $25! I bought one a while ago just for kicks! It
    works fine! Interface a couple of K thermocouples for about $10 each, and
    your on your way!
  5. SQLit

    SQLit Guest

    so sorry I would have thought that everyone would know to add www. and .com
    to the words.
    Guess I was wrong.
  6. James

    James Guest

    Same here! so did a google search it case it wasnt something else but still
    couldnt find anythinG!
  7. <grin>
    At one time I would have tried this - note that I never have!

    Use thermistors as the temperature sensors (max resistance=100k) and
    connect them as x & y pots to the "game" port of a sound card (x= pins 1-3
    y= pins 1-6). You can have 2 joysticks, so that's 4 possible thermistors.

    Your software would read the analogue inputs as a value of 0-255 where
    255=5v (short circuit) and 0=0v. Obviously, you won't get these, but
    something around the middle!

    You can use an output on the printer port to drive a relay if you put a
    NPN transistor (with base resistor) in the way.

    Don't ask me about software - I haven't programmed in years!

    Follow-ups set to alt.electronics only.
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