NI 9209 - Resolution of Voltage Measurement

[linu95k]

What if I use a 5V 2.4A SMPS and connect all my know shunt resistors of known value say 1Ohm and the use the same principle to measure the voltage drop across the resistors using NI 9209 will that work?

So the positive terminal of the SMPS is connected one end of the 1Ohm resistor (Qty: 56) across each of the resistors an AI channel is connected, there are 56 unknown resistances connected in series with the 1Ohm resistors, AI channels are connected across each of the Unknown Resistances.

Doubts:

1. What should be the Rating of the 1Ohm shunt Resistance so that it withstand the current?

2. Will 2.4A current be sufficient for calculation?

3. What will be the accuracy that we can expect with this setup?

[GerdW]

Hi linu,

---

@linu95k wrote:

1. What should be the Rating of the 1Ohm shunt Resistance so that it withstand the current?

2. Will 2.4A current be sufficient for calculation?

3. What will be the accuracy that we can expect with this setup?

---

1+2: Apply Ohm's law with Kirchhoff's rules! This is pretty basic electronics stuff, I even learned that in school…

3. Accuracy depends on accuracy of all items in your system, from power supply to used resistors to DAQ accuracy. You need to account all of them in your accuracy calculation…

It really would help when you would supply an electronics schematic next to the whole paragraph of words. An image is worth a 1000s words…