Shop OBEX P1 Docs P2 Docs Learn Events
Instrumentation amps — Parallax Forums

Instrumentation amps

ArchiverArchiver Posts: 46,084
edited 2001-10-11 17:19 in General Discussion
There are some precision, low-noise chips and modules designed specifically
for instrumentation amps, but I can't remember the numbers. We used
Burr-Brown modules on the oilfield stuff I used to work on.

Do a search in Yahoo for PRECISION OP-AMP and you should get quite a few web
matches.

Original Message

> If I wanted to measure pressure using several pressure sensors, then I
would need an instrumentation amp for each sensor. What would be the easiest
way to connect them to my a/d converters using the least amount of hardware?
The last one I made used several op amps which consisted of two chips and
some pots and a bunch of perfect resistors. Do they have this in an IC
package?

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2001-10-09 17:52
    I think you're looking for the Burr Brown INA105 . They are precision op
    amps with 4 precision resistors configured to make a unity gain difference
    amplifier. The resistors are 25K ( if I remember correctly ). If you need
    higher input impedance or gain, try an INA121. I've had good luck with them.
    Mike

    At 10:25 AM 10/9/2001 -0500, you wrote:
    >There are some precision, low-noise chips and modules designed specifically
    >for instrumentation amps, but I can't remember the numbers. We used
    >Burr-Brown modules on the oilfield stuff I used to work on.
    >
    >Do a search in Yahoo for PRECISION OP-AMP and you should get quite a few web
    >matches.
    >
    >
    Original Message
    >
    > > If I wanted to measure pressure using several pressure sensors, then I
    >would need an instrumentation amp for each sensor. What would be the easiest
    >way to connect them to my a/d converters using the least amount of hardware?
    >The last one I made used several op amps which consisted of two chips and
    >some pots and a bunch of perfect resistors. Do they have this in an IC
    >package?
    >
    >
    >
    >
    >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/

    _________________________________
    Mike Walsh
    walsh@i...


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2001-10-09 17:57
    If I wanted to measure pressure using several pressure sensors, then I would
    need an instrumentation amp for each sensor. What would be the easiest way to
    connect them to my a/d converters using the least amount of hardware? The last
    one I made used several op amps which consisted of two chips and some pots and a
    bunch of perfect resistors. Do they have this in an IC package?


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2001-10-09 21:08
    Added to Mike's and Rodent's suggestions is that the INA121 has
    differential FET inputs which means that you can use large input
    resistors. I use them with 1 Mohm input resistors. You can also include
    components for low-pass filtering at the input, as shown in the BB ap
    notes. If you don't need the large input impedance of FET inputs,
    Burr-Brown has a series of INA1-- chips with lower input impedance.

    Dennis

    On Tue, 9 Oct 2001, Mike Walsh wrote:

    > I think you're looking for the Burr Brown INA105 . They are precision op
    > amps with 4 precision resistors configured to make a unity gain difference
    > amplifier. The resistors are 25K ( if I remember correctly ). If you need
    > higher input impedance or gain, try an INA121. I've had good luck with them.
    > Mike
    >
    > At 10:25 AM 10/9/2001 -0500, you wrote:
    > >There are some precision, low-noise chips and modules designed specifically
    > >for instrumentation amps, but I can't remember the numbers. We used
    > >Burr-Brown modules on the oilfield stuff I used to work on.
    > >
    > >Do a search in Yahoo for PRECISION OP-AMP and you should get quite a few web
    > >matches.
    > >
    > >
    Original Message
    > >
    > > > If I wanted to measure pressure using several pressure sensors, then I
    > >would need an instrumentation amp for each sensor. What would be the easiest
    > >way to connect them to my a/d converters using the least amount of hardware?
    > >The last one I made used several op amps which consisted of two chips and
    > >some pots and a bunch of perfect resistors. Do they have this in an IC
    > >package?
    > >
    > >
    > >
    > >
    > >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/
    >
    > _________________________________
    > Mike Walsh
    > walsh@i...
    >
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
    >
    >
    > 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 2001-10-11 17:19
    A LM-11 or OP-07 are really clean op amps that work great with
    differential (piezo resistive bridge) type transducers. Parts count
    is very low. LM11 may be hard to find, OP-07's are everywhere.

    regards
    rich

    --- In basicstamps@y..., "Ricky Konvicka" <ricky@m...> wrote:
    > If I wanted to measure pressure using several pressure sensors,
    then I would need an instrumentation amp for each sensor. What would
    be the easiest way to connect them to my a/d converters using the
    least amount of hardware? The last one I made used several op amps
    which consisted of two chips and some pots and a bunch of perfect
    resistors. Do they have this in an IC package?
    >
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
Sign In or Register to comment.