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supply voltage for the sensor

Discussion in 'Sensors and Actuators' started by vamsee, Jan 10, 2013.

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  1. vamsee

    vamsee

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    Jan 10, 2013
    Hi!!

    i am using HBM Data acquisition, with which i calibrate the hall voltage. The hall sensor needs supply voltage to activate which we can not get from this DAQ. Only output pin of the hall sensor is connected to DAQ and the +ve and gnd connection must be connected to the external power supply.

    which power supply suits better.

    thanq
     
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    I don't understand the question.

    We need a lot more information.

    What Hall sensor?

    Post links to the data acquisition system and the Hall sensor.

    Post a schematic diagram of what you have so far.

    What power supplies are you considering?
     
  3. vamsee

    vamsee

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    Jan 10, 2013
    Hall sensor: http://docs-europe.electrocomponents.com/webdocs/0d88/0900766b80d88153.pdf

    HBM MGC plus ML01 amplifier DAQ: http://www.hbm.com/fileadmin/mediapool/hbmdoc/technical/b0554.pdf
    check pg 8

    With this DAQ I cannot get activate my hall sensor, where as with National Instruments 6008 DAQ, there is port for +5V and gnd, at which we can activate the sensor. I contacted HBM service center and they said, I cannot directly connect the hall sensor to the DAQ, only output of the hall sensor can be connected, but to activate the sensor i need external supply. So what supply shud i use.. Is TRACOPOWER good? suggest some cheaper supply voltages..

    thanq
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

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    I guess any good 5V supply will do. Just make sure it has a quiet and stabel output voltage. So probably a supply using a linear regulator is better than one using a switch mode regulator. You may need to insert an LC-filter between the supply and the sensor to further reduce noise.
     
  5. BobK

    BobK

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    And don't forget to connect the ground of the 5V supply to that of the DAQ board.

    Bob
     
  6. tedstruk

    tedstruk

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    Jan 7, 2012
    I didn't know that sensors could be connected to power sources. I thought sensors were impelled, initiated within a circuit, and that if you charge them, they would fail. Could it be that your test worked, but in the creation you put power to the sensor and blew it out? don't know, but i did that once too.
     
  7. davenn

    davenn Moderator

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    depends on the type of sensor
    some are passive, dont require power --
    some are active, do require power -- eg IR sensors in a TV, DVD etc

    Dave
     
  8. vamsee

    vamsee

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    Jan 10, 2013
    Hi everyone!! Thanx all for helping :)

    Pls help me in this as well,

    http://docs-europe.electrocomponents.com/webdocs/0e18/0900766b80e182ee.pdf

    the above link shows the power supply for my hall sensor..

    My question is that is that possible to connect the neutral and live wires of the tracopower to the electrical socket directly?
    and other 2 wires with +ve to the hall sensor +ve and -ve to the hall sensor gnd..

    Thanx in advance
     
  9. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Those are cute little power supplies. The output ripple is pretty high though.

    Harald addressed this earlier in this thread, in post #4. These are switching converters and they produce a lot of output ripple. You'll need a filter - either inductor-capacitor or resistor-capacitor - between the power supply and the transducer. Also the power supplies will probably generate quite a lot of common-mode noise, which may cause measurement errors. Linear power supplies would be better, as suggested by Harald.

    Also they're probably way over-rated for your application. The Hall effect transducer only needs 8 milliamps maximum.

    It's a shame you can't get a +5V feed from the DAQ unit itself. It probably has a +5V rail inside it, which could probably tolerate a small extra load.
     
  10. Harald Kapp

    Harald Kapp Moderator Moderator

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    At 8mA you could use a 9V batttery block plus a 5V linear regulator with some decoupling capacitors to supply the sensor with a stable low noise operating voltage.

    And it's safe, no messing around with mains power.

    Harald
     
    Last edited: Jan 11, 2013
  11. vamsee

    vamsee

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    Jan 10, 2013

    Hi thanx for the reply..

    if u dont mind, can u recommend me the power supply with the link provided..
     
  12. vamsee

    vamsee

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    Jan 10, 2013
    Thanq,

    i understood, but i dont want to use batteries(temporary supply)

    tats y i want to use power supply which can be fixed to the socket, so tat we get constant supply.

    Pls help me if i am wrong..
     
  13. Harald Kapp

    Harald Kapp Moderator Moderator

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    Get a decent lab bench power supply then.
     
  14. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    It might also be feasible to use a solar cell to power the transducer, with a light bulb to supply the light energy to the solar cell. This will give a very clean supply voltage with no common-mode noise. You would need a regulator on the solar cell output; use a low-dropout (LDO) 5V regulator. (Older regulators like the 78L05 draw significant quiescent current.)
     
  15. BobK

    BobK

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    Do you understand the difference between a switching and linear power supply, and why noise in the power supply is bad when powering a sensor?

    Bob
     
  16. vamsee

    vamsee

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    Jan 10, 2013
    HI!! Thanq all once again..

    I need a clarification,
    is that possible to add USB jack in the PCB panel (solder it) then 5V voltage regulator and then to hall sensor?

    My idea is to get the power from my laptop

    Any changes in my idea is welcomed..
     
  17. Harald Kapp

    Harald Kapp Moderator Moderator

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    No. The USB supply is already at 5V. YOu can't regulate that to 5V. Any linear regulator (as recommended for this application) will need a higher input voltage than its output voltage. This input-output differential can be a few 100 mV up to a few volts, depending on the type of regulator.
    You could use this method if the sensor operates at less than 5V (e.g. 3.3V). You can regulate 3.3V from % V using a linear regulator. But don't assume that the 5V from the PC/Laptop are accurate and clean. They are probably rather noisy. This would make the volate not well ssuited for calibrating sensors unless you carefully filter the noise.

    Google "Benchtop Power Supplies" for off-the-shelf power supplies.
     
  18. vamsee

    vamsee

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    0
    Jan 10, 2013
    Thanq Harald :)

    My DAQ has inbuilt filter and amplifier..I guess it takes care of the noise filtering..

    So now i should fix USB jack and Hall Sensor and then to the DAQ.. is that correct?
     
    Last edited: Jan 14, 2013
  19. Harald Kapp

    Harald Kapp Moderator Moderator

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    Try it. I can't tell you whether the DAQ's filtering is sufficient.
     
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