how to hookup a digital panel meter

[peter g]

hi forum members, I need help hooking up a model CX102B dpm. I want to use it to read 0-200v and 0-1a. is it possible to use just one dpm and switch between volts and amps? can a member supply a diagram with appropriate resistance values and hookup.thanks.

 

[D.A.(Tony)Stewart]

CX102B is rated for 0.2V

Thus for a 200V 1A you need 3 resistors and a >200v rated 2A DPDT switch.

Voltage divider 1000:1 Choose 1M:1k
HV rated if you expect transients on line. 1/4W are rated for 500V

1Adc for 0.1V requires shunt = 0.1 Ohm 1/4W

1Aac requires a precision OpAmp full wave rectifier off 5V.

 

[peter g]

thank you for the information. i'am afraid I also need a hookup diagram. I assume using only one dpm will work. can you supply a hookup scheme?

 

[D.A.(Tony)Stewart]

Is this for AC or DC?

Why not get a 2nd DPM instead of a switch?

 

[peter g]

this is for dc. the enclosure I have for this project is too small to mount 2 dpm's. I figure why use two, when you can use one.

 

[D.A.(Tony)Stewart]

Is this some kind of Solar Panel or what?

This is one way which senses the voltage drop on a 0.1 shunt resistor on the HV side and then taps 1/1000 on the high side for voltage so that both are differential 100mV to the 200mV DPM.

Another way is to put everything on the ground side, so the wires to the DPM are low V, but since DPMs are wired on the inside, no HV is accessible to pokey fingers.



The shunt consumes 0.1W at 1A. If you expect huge surge currents for any reason, a 1W or more can be used. Higher tolerance parts can be used if you don't mind or cant find 1% or 2%. The other resistors only draw 100uA.

Insert the shunt resistor R1 in a wire cut between battery + and its destination.

The DPM is powered by a 5V and MUST be floating from battery ground, otherwise a change is required.

 

[peter g]

I want to use the meter for a simple power supply. i'am confused about the 100v battery. forgetting the dual functioning (reading volt and current with single dpm). how would you connect the dpm to read just amps,ma, etc. thanks so much for your time and PATIENCE! i'am 77 years old and regrettably, I've became quite dense.