Making the Right Ammeter Selection

摘要

Nondestructive testing often involves small electrical currents to avoid damage to the device or material under test. As the scale of devices shrinks, so does test current. Today, nanoampere (10~(-9) A) measurements and lower are common. Measurement of such low level currents requires careful ammeter selection and use. An ammeter is an instrument for the measurement of electric current flow, calibrated in amperes. There are basically two types of ammeter architectures, shunt ammeters and feedback ammeters. Shunt ammeters are the most common and work in many applications; feedback ammeters are more appropriate when measuring small currents and their use is growing as test currents decrease in magnitude. However, the correct choice depends not only on the magnitude of the current, but also on the characteristics of the signal source.