Folks,
I've been experimenting with Four-terminal (Kevin) measurement to measure some low
resistance. I was trying to recreate what this guy did on a breadborad:
I've been experimenting with Four-terminal (Kevin) measurement to measure some low
resistance. I was trying to recreate what this guy did on a breadborad:
http://www.kerrywong.com/2011/08/14/...m-measurement/
Unfortunately in my tests the Device Under Test has a resistance value of under 1 milli ohm (while the 18 gauge copper wires are typically 10milli ohm per two inches roughly, which I use to connect the DUT to the breadboard)
I guess this is causing troubles for me.
On the two inner voltage sensing wires, I measure a voltage drop across the wire (which connects the DUT to the breadboard--I'm sticking the probes of my voltage meter onto the breadboard too )
Does anyone know whether this is because my DUT resistance is too low compared to the wires, that the Four-terminal sensing method just become not applicable for me?? or I'm missing something?
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Update: Ok.. i was measuring this because the measured value for the DUT is higher than what I got with a standalone Keithley instrument. So i was trying to see whether I'm picking up/accidentally measuring the wires or some other contact resistance other than that on the DUT.
I guess this is causing troubles for me.
On the two inner voltage sensing wires, I measure a voltage drop across the wire (which connects the DUT to the breadboard--I'm sticking the probes of my voltage meter onto the breadboard too )
Does anyone know whether this is because my DUT resistance is too low compared to the wires, that the Four-terminal sensing method just become not applicable for me?? or I'm missing something?
+++++++++++++++++++++++++++++++
Update: Ok.. i was measuring this because the measured value for the DUT is higher than what I got with a standalone Keithley instrument. So i was trying to see whether I'm picking up/accidentally measuring the wires or some other contact resistance other than that on the DUT.
In theory there should be negligible currents on the voltge sensing wires.
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