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Airpax A175: Difference between revisions
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The '''Airpax A175''' is an SPDT break-before-make chopper with a coil designed for approximately | The '''Airpax A175''' is an SPDT break-before-make chopper with a coil designed for approximately | ||
6.3 V<sub>AC</sub> at 60 Hz. It is used in the [[067-0596-00]], [[067-0543-99]], and the [[067-0502-01]]. | 6.3 V<sub>AC</sub> at 60 Hz. It is used in the [[067-0596-00]], [[067-0543-99]], and the [[067-0502-00]], and [[067-0502-01]]. | ||
The use of a chopper to make precise DC measurements is a well known and trusted technique, | |||
using instruments that are sensitive to AC, but not capable of drift-free DC performance. | |||
The chopping technique can be used for calibration, comparing a device under test with a reference. | |||
In this case, the result of chopping is viewed on an oscilloscope, possibly | |||
with a preamplifier between the output of the chopper and the input of the oscilloscope. The operator adjusts the device under test to minimize the amplitude observed on the | |||
oscilloscope. The vertical sensitivity, DC accuracy, and DC drift performance of the | |||
oscilloscope and preamplifier are not critical if the goal is simply to calibrate the device | |||
under test for optimal match with reference. However, if the objective of the calibration | |||
is to provide assurance that the error is less than some specific value, then the gain of the | |||
preamplifier and oscilloscope matters. Still, the gain of the preamp and oscilloscope only | |||
affect the accuracy of the tolerance, which is typically around 10%, (e.g., +/- 0.01% or +/- 0.3%). | |||
[[Image:Airpax 175 ad.jpg|700px]] | [[Image:Airpax 175 ad.jpg|700px]] | ||