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  1. #1
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    variable resistor tool



    members,

    I recently worked with a fella who produced out of a bag a variable resistor tool

    in short it was used for replacing/tricking thermistors on AC systems.

    he said after he found it in my pocket they were available on line, OK please give a clue where................................................................................

    I have looked at making one as parts could be sourced from maplin RS ect but this box of tricks was just right for the job, croc clips/prongs and a twist selector for ohms

    any clues on where to get one?


    Paul


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  2. #2
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    Re: variable resistor tool

    Variable resisitor tool?... is that the same as a 10k pot? If so they're available at RS, Farnells, and Maplins as you've seen. Does your mate sustitute the thermistors with a pot then trim the resisitance to match the thermistors design parameters, then measure the the setting value of the pot?
    Last edited by chilliwilly; 22-01-2011 at 11:35 PM.

  3. #3
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    Re: variable resistor tool

    Hisuperswill.
    I may have the wrong idea, but what I have is old fashioned by todays standards.
    It is known as a decade box.
    A search under that title may clarify?
    Grizzly
    Last edited by Grizzly; 23-01-2011 at 12:49 AM.

  4. #4
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    Re: variable resistor tool

    Quote Originally Posted by chilliwilly View Post
    Variable resisitor tool?... is that the same as a 10k pot? If so they're available at RS, Farnells, and Maplins as you've seen. Does your mate sustitute the thermistors with a pot then trim the resisitance to match the thermistors design parameters, then measure the the setting value of the pot?
    thats the toy
    Paul


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  5. #5
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    Re: variable resistor tool

    Quote Originally Posted by Grizzly View Post
    Hisuperswill.
    I may have the wrong idea, but what I have is old fashioned by todays standards.
    It is known as a decade box.
    A search under that title may clarify?
    Grizzly
    Grizzly,

    I will look into this
    Paul


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  6. #6
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    Re: variable resistor tool

    Hi superswill
    the resistances I have come across are 10K, 8K, 5K, 3K and 2K for space temps and something like 180ohms on an oil temp. So best bet is to get one with a trim pot similar to what chilliwilly has suggested. That way with any sensor you can have control over the dead band of the switching too.

  7. #7
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    Re: variable resistor tool

    The difference between genius and stupidity is that genius has its limits.

    Marc

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    Re: variable resistor tool

    i made one from cpc catalogue if you need any help they have a good technical line

  9. #9
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    Re: variable resistor tool

    just the ticket, ordered two, thank you marc
    Paul


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  10. #10
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    Re: variable resistor tool

    Let me know if they work will you?

    I was thinking of ordering one of them a few weeks back.
    The difference between genius and stupidity is that genius has its limits.

    Marc

  11. #11
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    Re: variable resistor tool

    Quote Originally Posted by marc5180 View Post
    Let me know if they work will you?

    I was thinking of ordering one of them a few weeks back.
    the Guinea pig will test and update
    Paul


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  12. #12
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    Re: variable resistor tool

    Go for a 10 turn pot as a single turn pot will not give you the accuracy

  13. #13
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    Re: variable resistor tool

    Quote Originally Posted by mbreward View Post
    Go for a 10 turn pot as a single turn pot will not give you the accuracy
    Thank for for the info
    Paul


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  14. #14
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    Re: variable resistor tool

    http://uk.rs-online.com/web/search/s...ubRange=Decade Boxes#breadCrumb

    Not got one myself but got a mate who swears by his..

    Ginge

  15. #15
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    Re: variable resistor tool

    Quote Originally Posted by marc5180 View Post
    Let me know if they work will you?

    I was thinking of ordering one of them a few weeks back.

    Marc,

    is working well, i went for the CPC one

    a few extra "mods" later mind

    see link:

    https://www.yousendit.com/download/M...NmMyWGMwTVE9PQ
    Paul


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