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HELP Control Varying Resistances — Parallax Forums

HELP Control Varying Resistances

ArchiverArchiver Posts: 46,084
edited 2001-11-27 20:11 in General Discussion
I need to be able to somehow change the resistance between two
outputs. For example with P0 and P1 set as outputs, I need an
external device to see 100k between them and then with a changes of
code, make it 50k or 0. Any ideas would be greatly appreciated
because I have been scratching my head for awhile on this. Thanks.

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2001-11-27 18:33
    In a message dated 11/27/01 12:31:49 PM Central Standard Time,
    consigli@p... writes:


    > I need to be able to somehow change the resistance between two
    > outputs. For example with P0 and P1 set as outputs, I need an
    > external device to see 100k between them and then with a changes of
    > code, make it 50k or 0. Any ideas would be greatly appreciated
    > because I have been scratching my head for awhile on this.

    Dallas Semiconductor makes a variety of digital pots that you can control
    very easily with SHIFTOUT.

    -- Jon Williams
    -- Parallax


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2001-11-27 18:41
    Perhaps there is a better solution, but off the top of
    my head I believe that an "audio volume knob" would do
    the trick, as on a home stero. Basically I believe
    that it is just a precision potentiometer with a
    stepper motor attatched to it for the fine control up
    and down the scale. You could build your own, but I
    believe I have seen surplus for sale at Jameco or
    maybe Electronic Goldmine. Going this route would
    just be a matter of controlling the stepper to vary
    the resistance of the pot. [noparse]:)[/noparse]
    ross

    --- consigli@p... wrote:
    > I need to be able to somehow change the resistance
    > between two
    > outputs. For example with P0 and P1 set as outputs,
    > I need an
    > external device to see 100k between them and then
    > with a changes of
    > code, make it 50k or 0. Any ideas would be greatly
    > appreciated
    > because I have been scratching my head for awhile on
    > this. Thanks.
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
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    > Text in the Subject and Body of the message will be
    > ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to
    > http://docs.yahoo.com/info/terms/
    >
    >


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  • ArchiverArchiver Posts: 46,084
    edited 2001-11-27 18:50
    How about a digital potentiometer? You can send it a serial value from
    your Stamp and it will change the output resistance accordingly. Plus,
    you only need to use one Stamp pin. Digital pots are available through
    Maxim <http://www.maxim-ic.com/>www.maxim-ic<http://www.maxim-ic.com/>.com
    and others in several values. Maxim will also provide free samples for you
    to try.

    Tim


    At 06:27 PM 11/27/2001 +0000, you wrote:
    >I need to be able to somehow change the resistance between two
    >outputs. For example with P0 and P1 set as outputs, I need an
    >external device to see 100k between them and then with a changes of
    >code, make it 50k or 0. Any ideas would be greatly appreciated
    >because I have been scratching my head for awhile on this. Thanks.
    >
    >
    >To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    >from the same email address that you subscribed. Text in the Subject and
    >Body of the message will be ignored.
    >
    >
    >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
  • ArchiverArchiver Posts: 46,084
    edited 2001-11-27 19:43
    How about using a SPDT relay (solid state?) to control whether a path is
    through a 0 ohm or 50K ohm resistor? Do it twice and you have a solution.

    There's also something like a digital volume control which can step up and
    down based on control pulses.


    On Tue, 27 Nov 2001, Klutch wrote:

    > Perhaps there is a better solution, but off the top of
    > my head I believe that an "audio volume knob" would do
    > the trick, as on a home stero. Basically I believe
    > that it is just a precision potentiometer with a
    > stepper motor attatched to it for the fine control up
    > and down the scale. You could build your own, but I
    > believe I have seen surplus for sale at Jameco or
    > maybe Electronic Goldmine. Going this route would
    > just be a matter of controlling the stepper to vary
    > the resistance of the pot. [noparse]:)[/noparse]
    > ross
    >
    > --- consigli@p... wrote:
    > > I need to be able to somehow change the resistance
    > > between two
    > > outputs. For example with P0 and P1 set as outputs,
    > > I need an
    > > external device to see 100k between them and then
    > > with a changes of
    > > code, make it 50k or 0. Any ideas would be greatly
    > > appreciated
    > > because I have been scratching my head for awhile on
    > > this. Thanks.
    > >
    > >
    > > To UNSUBSCRIBE, just send mail to:
    > > basicstamps-unsubscribe@yahoogroups.com
    > > from the same email address that you subscribed.
    > > Text in the Subject and Body of the message will be
    > > ignored.
    > >
    > >
    > > Your use of Yahoo! Groups is subject to
    > > http://docs.yahoo.com/info/terms/
    > >
    > >
    >
    >
    > __________________________________________________
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    >
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    >
    >

    Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
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  • ArchiverArchiver Posts: 46,084
    edited 2001-11-27 20:11
    I have a DS1267 here, but I think you need 3 Stamp pins ... one for
    reset, one for the clock, and one for the data. This may work though.

    --- In basicstamps@y..., Timothy Medema <timm@c...> wrote:
    >
    > How about a digital potentiometer? You can send it a serial value
    from
    > your Stamp and it will change the output resistance accordingly.
    Plus,
    > you only need to use one Stamp pin. Digital pots are available
    through
    > Maxim <http://www.maxim-ic.com/>www.maxim-ic<http://www.maxim-
    ic.com/>.com
    > and others in several values. Maxim will also provide free samples
    for you
    > to try.
    >
    > Tim
    >
    >
    > At 06:27 PM 11/27/2001 +0000, you wrote:
    > >I need to be able to somehow change the resistance between two
    > >outputs. For example with P0 and P1 set as outputs, I need an
    > >external device to see 100k between them and then with a changes of
    > >code, make it 50k or 0. Any ideas would be greatly appreciated
    > >because I have been scratching my head for awhile on this. Thanks.
    > >
    > >
    > >To UNSUBSCRIBE, just send mail to:
    > > basicstamps-unsubscribe@y...
    > >from the same email address that you subscribed. Text in the
    Subject and
    > >Body of the message will be ignored.
    > >
    > >
    > >Your use of Yahoo! Groups is subject to
    http://docs.yahoo.com/info/terms/
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