Tech Notes
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Title: What is the thermistor excitation current for the 1529 and how does it switch?
Created: 1 Feb 2013
Last Revised:
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Applies To: 1529
Problem Description: What is the resistance value that the 1529 switches from on to the other? Is there any way of forcing the 1529 to a single current?
Resolution/Work Around: The current switches from 10 uA to 2 uA when the resistance exceeds 47 kohms and switches from 2 uA to 10 uA when the resistance falls below 43 kohms. The current setting is automatic, and there is no way to override the automatic current control in this product. If the current was forced to a higher current, the voltage could be too high and exceed the range of the ADC, giving a false reading. Or self-heating could be excessive. If the current was forced to a smaller current at low resistances the noise would be much greater.
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Other Information: The 1529 uses current reversal even when measuring thermistors, unless it is in fast sample mode.