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Help i want to make a 10 amp pannel meter

Discussion in 'General Electronics Chat' started by Bartx7000, Dec 3, 2002.

  1. Bartx7000

    Bartx7000 New Member

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    Hello i am trying to make a 10 amp pannel meter for a power supply that i have made. I plan on using a digital meter that i bought form Jameco Electronic. I know it is possible i am just not sure off the externel scmatics.

    The pannel meter that i am using is 175951. Here is the link to the data sheet on it.
    http://www.electro-tech-online.com/custompdfs/2002/12/175951.pdf

    Thanks in advance for your help.
     
  2. kinjalgp

    kinjalgp Active Member

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    I saw the datasheet of your DPM. It can accept a max. 200mV DC. So to measure 10A DC you should pass your current through a shunt resistor such that it will drop 200mV across it when 10A current is passed through it. Here 200mV is the full scale. But you can also choose any other value say 10mV or 100mV(Easy to read) and calculate your resistor value as shown.
    So the value of resistor will be
    R=V/I
    R=10mV/10A
    R=0.001 Ohms

    The power dissipated will be I*I*R=10*10*0.001=0.1 Watts
    The power dissipating capacity of resistor should be more than 0.1W for safety. 0.5W is ok.

    Use this resistor in series with your power supply's positive rail and the two ends of the resistor will be your input lines to DPM.

    If the resistor value is difficult to get use full scale range of 100mV and calculate the resistor value accordingly. I have chosen 10mV as fullscale because the LCD reading will be directly in amperes and you'll not need to do any calculations.

    Hint: You can also use resistors in parallel to get the desired value.
     
  3. Bartx7000

    Bartx7000 New Member

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    Current Shunt

    Where do I get a Current Shunt?
     
  4. dave

    Dave New Member

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  5. kinjalgp

    kinjalgp Active Member

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    Its available in the market. Actually it doesn't look like a resistor but its a small piece of thick metal wire. The easiest way to get such a piece is from old non functional digital multimeters. These use this shunt for 10A range. So if you have one open it and desolder the shunt. Or now a days very cheap China make digital multimeters are available in the market (around $5 in my country). So if you don't find shunt anywhere spending $5 will be worth it if this project is very important.

    Or the other crude method is to connect hundred 1 Ohm (1%) precision resistors in parallel. 8)
     
  6. Bartx7000

    Bartx7000 New Member

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    Thanks Do you knoww off any place's such as websites that carry theise.
    I really dont want to put 100 1 ohm resistors in series.
    Thanks Jason
     
  7. kinjalgp

    kinjalgp Active Member

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    No I don't know any place on the net where you can buy these because I never buy electronic components from the net.
    The easiest way to get it is as I told you from Non-functional Digital multimeters.
     
  8. hantto

    hantto Member

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    I have an idea. You could take a 59mm long copper wire, with 1mm² and put in the circuit instad of 100resistors. It will give a 0.001 ohm resistance. :D
     
  9. Bartx7000

    Bartx7000 New Member

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    Thanks what gauge is that wire.
     
  10. hantto

    hantto Member

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    Well as i said a 1mm² wire, it is the same as 1.13mm Ø (according to my calculations) and that would be the same as standard wire gauge 6 (i think).

    Hope you got some help :D
     

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