Keithley 2566 Drift in Lo Res free download

File name 2566 Drift in Lo Res.pdf

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 Problem: Reading Drift in Low Resistance Measurements Probable Cause: ity. Apply the test current and measure the circuit temperature during the meas- Thermoelectric Voltages the voltage. Then reverse the polarity of urement cycle will cause changes in the Thermoelectric voltages are the most the test current and measure the voltage thermal EMFs that will not be completely common cause of reading drift in low re- again. Add the two voltage measure- cancelled, and some error will result. sistance measurements. They are caused by ments and divide the result by two. This differences in temperature between different completely cancels the thermal EMF in B. Offset Compensation Technique--Make parts of the measurement circuit. the measurement. two voltage measurements, one with the test current enabled, the other with the Remedies This method requires a low noise voltme- test current disabled. Subtract the results A. Current