kelvin type Ohm Meter

[KlausST]

Hi,

The suggestions of SunnySkyguy are all correct.

Down to 1mOhm you can work with DC excitation and chopper opamps.

I doubt DC gives good results down to 1uOhm. Here i´d go for AC excitation. But that is out of question here.

****
Maybe you use a DAC to control the current source.
If output = 0..5V and known shunt resistance is 0.1ohms you could just use a voltage divider for current source input.

The FET parameters for low side current source are:
N-CH
VDS: >6, --> >12V
ID: > 1A
PTot > 6W: mind a good package for heatsink
VGSth 0.5...1.5V

Klaus

 

[Venkadesh_M]

Yeah you can follow them. but i thought you need a simple solution.

Hi KlausST

The FET parameters for low side current source are:
N-CH
VDS: >6, --> >12V
ID: > 1A
PTot > 6W: mind a good package for heatsink
VGSth 0.5...1.5V

Its about which circuit ?

 

[Ashkar]

@Klaus

I think I might want to use a Faircild "http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Components/General/FQP30N06L.pdf"
It Looks promising for our setup.

 

[Ashkar]

I am using AD707 For my Voltage gain application.
It seems to be a good choice for the application.

So I have a situation here,Actually I need to know how do I choose gain for the OP-Amp.
The above Image is right to be used with the Formula Av=1+(Rf/R1)

Now I would Be using a Input Voltage of 0.001v(0.001 Ohm DUT),Av has to be 1000 i.e Rf and R1 will be 10k and 10 Mega Ohms Respectively.

 

[KlausST]

Hi,

I looked at www.analog.com and AD707.
Tha same could you do

The first words are "obsolete product"..

Klaus

 

[Ashkar]

Klaus you are right,Its a obsoleted product ,:shock: Now I think of getting my hands on OP07,Bought some already.