1. Anthony Mogavero

    Thread Starter New Member

    Mar 24, 2012
    2
    0
    I puchased this meter, (CX101A), to monitor both voltage, as well as current. I've been informed by the seller that I can do both by using a selector switch, to toggle between the two. I was already aware of that point. My input and measured voltage is 12-14vdc and have followed the schematic wiring diagram, that came with the meter, with the applicable resisters shown in the chart for 0-20vdc. (see attachment)
    Someone posted that this meter cannot share the same v- point, for input and measured voltage, nor can the measured voltage be the same as the souce voltage. However this is not true, as I have done so sucessfully.
    My real question about this meter is what terminals, on the meter, do I place the shunt, in order to measure dc current of about 20 amps? I already have the shunt, it is rated at 100amps , however it is only 100mv instead of 200mv. Does the shunt go across (GND & VIN) to measure current, with the same resisters in the circuit as are used to measure the voltage, or are the resisters only used in the circuit to measure the voltage?
    Because the meter is 200mv full scale deflection can I still use the 100mv shunt directly, or will I have to add more resisters to accomodate the circuitry?
    I've made several attemps to retreive this information from the seller, with unsatisfying results. Can someone help me on this one?
     
  2. #12

    Expert

    Nov 30, 2010
    16,284
    6,797
    You are going to have to set up the resistors for both the 200mv scale and the 20 volt scale. Use the 20V resistors to measure the 12-14 volts you mentioned and use the 200 mv setup to measure the voltage across the current shunt.

    and ps, your current shunt is awkward. I'd sure rather see 200 mv for 20 amps. It's just easier to not make mistakes that way!
     
  3. Anthony Mogavero

    Thread Starter New Member

    Mar 24, 2012
    2
    0
    I agree about the 200mv shunt. However nobody offers one, they're only availiable in 50 or 100mv, and eventhough I've had some electrical and electronics knowledge and experience, I'm not savvy enough to figure out how to calculate the resistance values, or where to place them in the circuit. Thanks anyway for the response.