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Low DC voltage measurements

Posted: October 30th, 2014, 3:46 am
by RebTor
Hie everyone!

I have to develop a DCPD (direct current potential drop) and would like to measure DC voltage from 0.5 to 5mV.The resolution of multimeter
should be 100nV and accuracy +- (50ppm of reading + 1.23uV).
Is it possible to get something like that?
Other task i DC current source which should power 0-20A. I have to measure this current as well.

Best regards

Re: Low DC voltage measurements

Posted: October 31st, 2014, 7:22 am
by Dale C
The Model 2182A nanovoltmeter would be able to handle the voltage measurement with no problem.
It is has a 10mV range with 1nA sensitivity and about 40nV of accuracy.
The Model 2260B-30-36 power supply from Keithley would be able to source up to 20A with no trouble.
It is a voltage supply that has a constant current mode. It can actually output up to 36A up to 30V.
These two units should satisfy your requirements.

Re: Low DC voltage measurements

Posted: November 2nd, 2014, 11:30 pm
by RebTor
Thank a lot.
Other problem I might meet is current-reversal method.
Could you recommend any switch for current-reversal method?

Best regards

Re: Low DC voltage measurements

Posted: November 4th, 2014, 8:38 am
by Dale C
I understand about needing the current reversal method.
That helps eliminate the thermal EMFs in the measurement.
The Keithley 6221 and 2182A are perfect for this. But maximum current is 100mA.
The 2400 series is also good for this but limited to 5A (model 2440).
But the 2260B-30-36 is only positive voltage or current so you would need a switch for the reversal.
Sorry, Keithley does not have any switches of that magnitude (30A).
The maximum switch current from Keithley is the Model 7053 at 5A. it also requires a Model 7001 switch mainframe.