Author Topic: beginners question about smu  (Read 246 times)

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Offline jude_elec

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beginners question about smu
« on: April 15, 2019, 06:00:41 pm »
I am trying to understand about keithley 2450 smu and smu in general and write a python driver for it
In order to see how it works im connecting it once to a dmm and once to a source meter
The source meter im using is b2902a agilent smu, when im sourcing for example 1.5 v with a limit of 0.8 amper, the voltage that appears on the screen of the source much smaller(less than 1 mv) than what ive set, but on the keithley smu that im measuring with the voltage is 1.5v, what is the voltage that appears on the source?

Ive read that it measures and source at the same time what does it mean? Does it mean that it switches between measure and source ?
Ive done some reading but still don’t fully understand, because I have a few option on the instrument-voltmeter, ammeter, and 4 other measure and source options.


Offline HighVoltage

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Re: beginners question about smu
« Reply #1 on: April 15, 2019, 09:18:29 pm »
You really should read the manuals !!!

You have set both the Keysight B2902A and the Keithley 2450 to source voltage and current.
And then hook one up to the other? How?
This is not a good setup !

To start, just hook up a resistor (may be 1 Ohm) to the B2902A and apply the same voltage and current limit,
to get a feeling for the instrument.

Then do the same on the 2450 to get a feeling for this instrument.

There are 3 kinds of people in this world, those who can count and those who can not.

Offline Brad O

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Re: beginners question about smu
« Reply #2 on: May 10, 2019, 05:16:53 am »
Did you figure this out? (you needed to press "Auto" on the B2902) I agree with HighVoltage's recommendation though, SMUs are very powerful but as a result they can seem more confusing than other instruments.  Start with something simple before attaching instruments to each other.

A point about hooking SMUs into each other.  SMUs are generally designed to handle their own power envelope (look at the IV charts in the datasheets, see how they're symmetric?), so hooking two SMUs of the same type into each other is almost always fine.  You have to be careful when connecting SMUs of different types to be sure one doesn't over-power and damage the other.  In this case, the B2902A has the same max power output as the 2450 so the 2450 should be able to handle even any mistakes you make, but I would still avoid trying to force over 1A into the 2450. 

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