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4 - 20mA output — Parallax Forums

4 - 20mA output

ArchiverArchiver Posts: 46,084
edited 2003-02-27 07:45 in General Discussion
Hello, I have an auto engine hooked up to a dynamometer to measure
torque. The i/p to the stamp will be from a prox. on the flywheel.
The o/p needed from the stamp is 4 - 20ma, to control a
proportional valve which in turn controls the water flow to
a 'turbine' mounted on the engine drive shaft. So the
faster the engine goes, the water valve opens more and more load is
applied to the engine. I have
looked at a 0 -10v o/p from a digital pot but wondered if a 4 -
20mA output s possible? I have not bought a valve yet so not sure on
what tyoe of control signal it requires. I wonder if anyone has
ideas on this type of application? I also may need a pot. on the
valve as feed back so the stamp knows the position of the valve.

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-02-24 01:18
    Let's say the car engine will turn between 600 & 6000 RPM with the sensor
    outputting a pulse every rev. Could you then count the number of rev's with the
    stamp and output to a serial D/A converter this number that could be turned into
    a voltage and then a 4-20 ma current? Sounds like a neat project.


    Leroy Hall
    http://home.fuse.net/leroy

    Original Message
    From: <andy@p...>
    To: <basicstamps@yahoogroups.com>
    Sent: Sunday, February 23, 2003 5:32 AM
    Subject: [noparse][[/noparse]basicstamps] 4 - 20mA output


    : Hello, I have an auto engine hooked up to a dynamometer to measure
    : torque. The i/p to the stamp will be from a prox. on the flywheel.
    : The o/p needed from the stamp is 4 - 20ma, to control a
    : proportional valve which in turn controls the water flow to
    : a 'turbine' mounted on the engine drive shaft. So the
    : faster the engine goes, the water valve opens more and more load is
    : applied to the engine. I have
    : looked at a 0 -10v o/p from a digital pot but wondered if a 4 -
    : 20mA output s possible? I have not bought a valve yet so not sure on
    : what tyoe of control signal it requires. I wonder if anyone has
    : ideas on this type of application? I also may need a pot. on the
    : valve as feed back so the stamp knows the position of the valve.
    :
    :
    : 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 2003-02-27 07:45
    I don't know if you have decided on a specific type or manufacture of valves but
    Belimo has a very good line of valves that can accept either voltage and or
    current. In addition they have feed back options available. Sorry I can't help
    with your main question, I too would be interested with any information you
    receive on the 4-20mA output from a stamp.
    Good luck,
    Troy S
    "andyfree86 <andy@p...>" <andy@p...>
    wrote:Hello, I have an auto engine hooked up to a dynamometer to measure
    torque. The i/p to the stamp will be from a prox. on the flywheel.
    The o/p needed from the stamp is 4 - 20ma, to control a
    proportional valve which in turn controls the water flow to
    a 'turbine' mounted on the engine drive shaft. So the
    faster the engine goes, the water valve opens more and more load is
    applied to the engine. I have
    looked at a 0 -10v o/p from a digital pot but wondered if a 4 -
    20mA output s possible? I have not bought a valve yet so not sure on
    what tyoe of control signal it requires. I wonder if anyone has
    ideas on this type of application? I also may need a pot. on the
    valve as feed back so the stamp knows the position of the valve.


    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.


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