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A g r e At e r m e A s u r e o f c o n f i d e n c e
Making Precision Low Voltage
and Low Resistance Measurements
introduction ............................................................................ 2 Low Resistance Measurements ........................................... 9 Applications
Low Voltage Measurements ................................................ 2 Lead resistance and four-Wire method .......................... 9 Low-V: Hall effect measurements ................................... 14
effects of error sources on Voltage measurements ....... 2 thermoelectric emfs & offset compensation methods ..... 9 Low-r: superconductor resistance measurements ..... 17
noise .................................................................................... 5 non-ohmic contacts .........................................................11 Selector Guide...................................................................... 18
common-mode current and reversal errors .................. 8 device Heating .................................................................. 12 Glossary ................................................................................ 19
dry circuit testing ............................................................ 12 Contact Us ........................................................................... 22
testing inductive devices ................................................ 13
begin
introduction | LoW VoLtAge meAsurements | LoW resistAnce meAsurements | LoW-V AppLicAtion: HALL effect meAsurements | LoW-r AppLicAtion: superconductor resistAnce meAsurements | seLector guide | gLossAry | contAct us
Low Voltage measurements
introduction effects of error sources on Voltage A B A
Low voltage and low resistance measurements are measurements T1 T2
HI
often made on devices and materials with low source ideally, when a voltmeter is connected to a relatively
impedance. This e-handbook discusses several potential low impedance circuit in which no voltages are present, EAB
LO
sources of error in low voltage measurements and how it should read zero. However, a number of error sources Nanovoltmeter
FeATured reSourceS
to minimize their impact on measurement accuracy, in the circuit may be seen as a non-zero voltage offset. n Troubleshooting
as well as potential error sources for low resistance These sources include thermoelectric eMFs, offsets low Voltage
The thermoelectric voltage developed by dissimilar
measurements, including lead resistance, thermoelectric generated by rectification of rFi (radio frequency metals A and B in a series circuit is: measurement
eMFs, non-ohmic contacts, device heating, dry circuit interference), and offsets in the voltmeter input circuit. Problems
EAB = QAB ( T1