usb 6008 current measurement

[Mohammed.Ashraf]

i just bought a current converter board that costed me 185 dollars !

can i simply replace it with a 250 ohms resistor ?!

 although what you are saying is logic , but i'm surprised from how much components and resistors i see in the current converter board 

Thanks in advance 

[timoteo]

Hello,

Is true that you can use that resistor or even configure the USB board with the internal resistor and no need or that external resistor...

But remember that the corrent you can measure are between 0 and 20mA if you need to measure higher current you need that convert.

Timóteo

[EEsRULEtheWORLD]

Hi, Mohammed.

Basically, the difference between the $185 current converter board and the 250 ohm resistor is the difference between an active and passive voltage-to-current converter, respectively.  The current converter board has more components to compensate for eventual external losses.

[Mohammed.Ashraf]

Thanks sara

so it's better to use a current converter when the accuracy and stability are strictly required ?

[EEsRULEtheWORLD]

Hi, Mohammed.

The current converter board may seem to be better for accuracy and stability, but it is only suitable for low-current applications.  The reason is that the op-amp and power source in the current converter board need to be able to withstand the input current supply.  Check the specifications of your current converter board to determine the current limitations.

[Mohammed.Ashraf]

Sarah

Right now i have a small problem , which is that the pressure sensor as well as the flow meter does not return any signal, maybe it needs to be supplied with voltage , but i don't know how to make this in case i'm using a 250 ohms precision resistor.

i'd appreciate it if it is possible to sketch me the right connection including the 2 conductor pressure transmitter , Resistor and supply 

attached to this message my connection to the current converter board , but it didn't work since the current converter board doesn't supply power to the sensor

 

Message Edited by Mohammed.Ashraf on 09-11-2009 10:46 AM

[AnalogKid2DigitalMan]

Mohammed:

Can you give the exact model number of your sensor and a link to the specifications or manual? The sensor does need a power source, with more info we can assist.

-AK2DM

EDIT: I missed the model number on your image (4446-a), I'll look into it.

Message Edited by AnalogKid2DigitalMan on 09-11-2009 10:36 AM

[Mohammed.Ashraf]

attached is the datasheet for the pressure sensor and the flow meter 

Thanks alot for your help , i really appretiate it 

[AnalogKid2DigitalMan]

Mohammed:

Can you supply the make and model of the converter box? Attached is the wiring method for direct connect to a DAQ card using the power supply and a resistor.

-AK2DM