Shunt resistor value query

Thread Starter


Joined Oct 31, 2009
Hi folks,

I have a dc circuit and wish to monitor current under a variety of situations - its got switching converters with outputs of 5V and 15V and a smaller LDO outputting 3.3v - the switchers are putting no more than 1A out and the LDO circa 150mA - also I want to measure efficiency so need to monitor the input current, this will be < 2A @ 24V

I am thinking of using a NI DAQ unit to read current values, but not sure about sizing them up -- I can use a divider to reduce the 15V & 24V range to manage the DAQ AI input limit, 10V.

I think the DAQ is better than using an op amp or dvms etc as they have high impedance and should give more accurate results, plus a single breadboard can be used to access all 4 signals

How can I best size up sense resistors? or does it even matter that much as you can specify them in the labview VI