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How To Read LVDT? — Parallax Forums

How To Read LVDT?

ArchiverArchiver Posts: 46,084
edited 2002-12-28 18:05 in General Discussion
Anyone ever interface a stamp to an LVDT? I have one mounted inside
a hydraulic cylinder that I need to read the position of. Anyone
know of any off the shelf products or circuits to do this?

Thanks,
Ron

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2002-12-27 16:16
    If memory serves me correctly, the LVFT has a pot that changes resistance
    with the linear position???


    Depending on how fast you need your feedback information, you have some
    options.

    If you do not need quick feedback, the POT command will work.

    If you need quick feedback, probably will need a BS2 SX and an A/D converter.


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2002-12-27 19:00
    A real nice visual of it's operation can be found at:

    http://ak-industries.com/lvdt.htm

    A google search will give even more data;;

    Sincerely,

    Leroy Hall
    http://home.fuse.net/leroy
    Original Message
    From: <ronjeremy912@h...>
    To: <basicstamps@yahoogroups.com>
    Sent: Friday, December 27, 2002 3:29 AM
    Subject: [noparse][[/noparse]basicstamps] How To Read LVDT?


    : Anyone ever interface a stamp to an LVDT? I have one mounted inside
    : a hydraulic cylinder that I need to read the position of. Anyone
    : know of any off the shelf products or circuits to do this?
    :
    : Thanks,
    : Ron
    :
    :
    : 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 2002-12-27 20:02
    Nice visual.

    if you paste the link into google, and search on that, you will be
    offered a 'translate this page'

    For some reason, I thought that a wheatstone bridge was the needed
    ampliphier for this.

    It appears that the curcuit is similar to the one used for a spring
    load cell. I think Beau has a simple schematic on his site. I know
    there are references in the archives.

    So much of what I see is Greek that French throws me for a loop.


    Dave



    --- In basicstamps@yahoogroups.com, "Leroy Hall" <leroy@f...> wrote:
    > A real nice visual of it's operation can be found at:
    >
    > http://ak-industries.com/lvdt.htm
    >
    > A google search will give even more data;;
    >
    > Sincerely,
    >
    > Leroy Hall
    > http://home.fuse.net/leroy
    >
    Original Message
    > From: <ronjeremy912@h...>
    > To: <basicstamps@yahoogroups.com>
    > Sent: Friday, December 27, 2002 3:29 AM
    > Subject: [noparse][[/noparse]basicstamps] How To Read LVDT?
    >
    >
    > : Anyone ever interface a stamp to an LVDT? I have one mounted
    inside
    > : a hydraulic cylinder that I need to read the position of. Anyone
    > : know of any off the shelf products or circuits to do this?
    > :
    > : Thanks,
    > : Ron
    > :
    > :
    > : 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 2002-12-28 02:19
    Sometimes a good visual can speak many words. I have often heard of an LVDT,
    but how
    does a transformer measure some thing? This visual answers that question nicely
    and the
    good part is you don't even have to ask the question to understand the answer.
    Thanks
    for asking your question, it has brought this subject into the light, where I am
    sure it
    will get good exposure..


    Sincerely,

    Leroy Hall
    http://home.fuse.net/leroy
    Original Message
    From: <davemucha@j...>
    To: <basicstamps@yahoogroups.com>
    Sent: Friday, December 27, 2002 3:02 PM
    Subject: [noparse][[/noparse]basicstamps] Re: How To Read LVDT?


    : Nice visual.
    :
    : if you paste the link into google, and search on that, you will be
    : offered a 'translate this page'
    :
    : For some reason, I thought that a wheatstone bridge was the needed
    : ampliphier for this.
    :
    : It appears that the curcuit is similar to the one used for a spring
    : load cell. I think Beau has a simple schematic on his site. I know
    : there are references in the archives.
    :
    : So much of what I see is Greek that French throws me for a loop.
    :
    :
    : Dave
    :
    :
    :
    : --- In basicstamps@yahoogroups.com, "Leroy Hall" <leroy@f...> wrote:
    : > A real nice visual of it's operation can be found at:
    : >
    : > http://ak-industries.com/lvdt.htm
    : >
    : > A google search will give even more data;;
    : >
    : > Sincerely,
    : >
    : > Leroy Hall
    : > http://home.fuse.net/leroy
    : >
    Original Message
    : > From: <ronjeremy912@h...>
    : > To: <basicstamps@yahoogroups.com>
    : > Sent: Friday, December 27, 2002 3:29 AM
    : > Subject: [noparse][[/noparse]basicstamps] How To Read LVDT?
    : >
    : >
    : > : Anyone ever interface a stamp to an LVDT? I have one mounted
    : inside
    : > : a hydraulic cylinder that I need to read the position of. Anyone
    : > : know of any off the shelf products or circuits to do this?
    : > :
    : > : Thanks,
    : > : Ron
    : > :
    : > :
    : > : 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/
    : > :
    : > :
    :
    :
    : 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 2002-12-28 16:53
    Leroy,

    Thanks for the link. There is also some good information and an
    illustration at:

    http://www.rdpelectrosense.com/displacement/lvdt/lvdt-principles.htm

    Site is also in english. After looking at how it worked, I was
    wondering if anyone had done this with a stamp. Looks like you have
    to measure phase angle of output waveform and compare it to the
    input. I'm not exactly sure how to go about doing that. Seems like
    you'd have to digitize the waveform and perform some trig functions
    on it - a task that could prove impossible with a stamp. Thought
    maybe someone knew of a chip or something that could do all this for
    you and then just give counts relating to position.

    Ron

    --- In basicstamps@yahoogroups.com, "Leroy Hall" <leroy@f...> wrote:
    > Sometimes a good visual can speak many words. I have often heard
    of an LVDT, but how
    > does a transformer measure some thing? This visual answers that
    question nicely and the
    > good part is you don't even have to ask the question to understand
    the answer. Thanks
    > for asking your question, it has brought this subject into the
    light, where I am sure it
    > will get good exposure..
    >
    >
    > Sincerely,
    >
    > Leroy Hall
    > http://home.fuse.net/leroy
  • ArchiverArchiver Posts: 46,084
    edited 2002-12-28 18:05
    The primary of the LVDT is fed with a signal that is coupled more or less to
    either
    secondary depending on the core's relative position. The amplitude of the
    signal
    appearing at either secondary would be dependent on the core's position. A
    simple diode
    bridge on the output of both end coils and a A/D converter from the bridge would
    give
    numbers relative to position. These numbers could easy be dealt with, with the
    stamp.
    This is how I would attack the problem anyway.


    Sincerely,

    Leroy Hall
    http://home.fuse.net/leroy
    Original Message
    From: <ronjeremy912@h...>
    To: <basicstamps@yahoogroups.com>
    Sent: Saturday, December 28, 2002 11:53 AM
    Subject: [noparse][[/noparse]basicstamps] Re: How To Read LVDT?


    : Leroy,
    :
    : Thanks for the link. There is also some good information and an
    : illustration at:
    :
    : http://www.rdpelectrosense.com/displacement/lvdt/lvdt-principles.htm
    :
    : Site is also in english. After looking at how it worked, I was
    : wondering if anyone had done this with a stamp. Looks like you have
    : to measure phase angle of output waveform and compare it to the
    : input. I'm not exactly sure how to go about doing that. Seems like
    : you'd have to digitize the waveform and perform some trig functions
    : on it - a task that could prove impossible with a stamp. Thought
    : maybe someone knew of a chip or something that could do all this for
    : you and then just give counts relating to position.
    :
    : Ron
    :
    : --- In basicstamps@yahoogroups.com, "Leroy Hall" <leroy@f...> wrote:
    : > Sometimes a good visual can speak many words. I have often heard
    : of an LVDT, but how
    : > does a transformer measure some thing? This visual answers that
    : question nicely and the
    : > good part is you don't even have to ask the question to understand
    : the answer. Thanks
    : > for asking your question, it has brought this subject into the
    : light, where I am sure it
    : > will get good exposure..
    : >
    : >
    : > Sincerely,
    : >
    : > Leroy Hall
    : > http://home.fuse.net/leroy
    :
    :
    : 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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