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Making a temperature regulator

Discussion in 'Electronic Basics' started by [email protected], Oct 12, 2005.

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  1. Guest

    I've got several things I'd like to regulate. A heat treating oven
    we have so that would need to go to at least 1800 degrees with
    regulation of plus or minus 25 degrees.
    Then an incubator for hatching duck eggs. This needs to be plus or
    minus 1 degree.
    What I don't know is what devices to use for the sensing. I really
    need some article or book on the subject. I took electronics for 2
    years about 10 years ago buy have almost no experience since then in
    it.
     
  2. w2aew

    w2aew Guest

    There are a lot of options for temperature sensing - everything from PN
    junctions (diode voltage), to various IC sensors, to thermocouples,
    RTDs, thermistors, etc. What you choose will highly depend on the
    application.

    There's a pretty good technical reference on Omega Engineering's
    website:
    http://www.omega.com/techref/
     
  3. Chris

    Chris Guest

    For sensing high temperatures, you'll need a thermocouple. Depending
    on the peak expected temperature, you could either use a K-type
    thermocouple, or one of the more esoteric higher temp ones, like an
    R-type T/C. These are good for fairly precise sensing of temperatures
    in this range.

    For very precise sensing of low temperatures (30-40C) your best bet is
    an RTD (Resistive Temperature Device). This will give you accuracy of
    within a couple of tenths of a degree.

    For either of the two applications, you'll need something called a
    temperature controller. This is a programmable device which accepts
    the sensor input, and has an output which controls the heat treating
    furnace or the incubator.

    Also, your heat treating furnace will probably need a ramp-soak
    feature, which makes the furnace temp rise at a timed, set rate to go
    from one temp to a second higher one (ramp), then maintains that temp
    for another set period of time (soak).

    A good one-stop source of information on temperature control is the
    Omega Engineering Temperature Handbook. Not only is there a lot of
    technical information, but also a wide variety of products available
    which will do the job for you. Best of all, the Temperature catalog is
    free. That's free, as in beer. Don't believe it, take a look:

    http://www.omega.com/

    Click "Free Literature" on the menu bar at the top of the webpage, then
    select Omega Product Handbooks (the Temperature handbook is the thick
    red one).

    A lot of the technical information is available in abbreviated form on
    the website. Just click around and have fun.

    Good luck
    Chris
     
  4. Jasen Betts

    Jasen Betts Guest

    for the kiln a thermocouple is probably the way to go
    for temps below boiling point there are semiconductor sensors like LM335
    that give a nice simple voltage output.
    feed the output into a comparator that also sees a correclty adjusted
    reference volttage and then into whhatever control device you want to use...
    (optocoupler to a triac, or a transistor to drive a relay.)

    you'll probably be wanting a fan in that incubator to keep the temperature
    even.


    Bye.
    Jasen
     
  5. Guest

    I've sent off for that free info from Omega and it should be a start
    to this. I liked that idea for the heat treat oven of having it so
    goes from one temp to another. That would really help
    Ken
     
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