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HOW TO SHORT THE OP-AMP'S INPUTS TOGETHER ?

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Minh Thanh

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This is first time that I heard " Short Inputs " .It 's terrible to me . I dont know how to short it . Could you help me about this, ?. Please you illustrate by picture so that I can understand it clearly . I attached a photo below . Thank you !
 

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AnalogKid

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Depends on the context. Why are you being instructed to short the inputs together? Shorting the inputs together will not damage anything, but it usually is not a good idea. If this is for some kind of performance/noise test, what is the test?

Also, are you sure they don't mean to short the input to ground?

ak
 

Minh Thanh

New Member
Depends on the context. Why are you being instructed to short the inputs together? Shorting the inputs together will not damage anything, but it usually is not a good idea. If this is for some kind of performance/noise test, what is the test?

Also, are you sure they don't mean to short the input to ground?

ak
Just to calibrate the circuit, first short the inputs together and adjust the offset potentiometer to obtain 0-mV output from the LM351.
 

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KeepItSimpleStupid

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PS: It's stupid design. Shorting the input may not even work in this case.

PH probe basics: https://www.omega.com/Green/pdf/pHbasics_REF.pdf
and http://www.ti.com/lit/an/snoa529a/snoa529a.pdf

I'd actually use any resistor > 10 meg ohms for the PH input. Shorting can conceivable make the OP amp go full scale.

LM351 Datasheet: http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00000453.pdf

PH is just one of those applications that a typical OP-amp won;t work well. It's also where guarding should be used at the inputs. Ib (Input bias current) is temperature sensitive. It's also a board where the board should be cleaned thoroughly and not touched afterwards.

The reference electrode is your best calibration. You should have a second reference too,
 
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