WEBVTT
Kind: captions
Language: en

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♪ Turn my motor on ♪

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We're demonstrating a
tachometer and motor diagnostics

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with a noncontact rotation sensor,

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which has digital quarature outputs,
each synchronized to rotation.

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An Arduino calculates and displays RPM
on a four-digit display.

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The analog meter shows
the variability of rotational speed,

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or instantaneous acceleration.

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This is often used for diagnostics.

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You can see occasional
large changes that peg the meter.

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Those may indicate something
intermittently catching in the motor.

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That sort of thing could be monitored
and if it worsens,

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might suggest the motor be replaced.

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Or if, for example,
friction increases,

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the variation increases
quite a bit, even though

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the RPM only drops a little.

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So this could indicate a problem.

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The sensor provides direction information.

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These two LEDs indicate

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clockwise and counterclockwise.

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We're using an inexpensive
diametrically-magnetized magnet

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on the end of the motor shaft.

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There's an NVE Web application
to check the sensor position,

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but it has a very wide tolerance

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because of the sensor's
wide magnetic range.

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We can also use the sensor
off-axis with a ring magnet.

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There's another Web app
to determine the best

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sensor position for that configuration.

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Here's the demo schematic.

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The sensor is connected to
two interrupt-capable inputs

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of the Arduino;

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the seven-segment display
is driven by a serial line;

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two LEDs indicate direction;

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and the PWM output goes to the meter.

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Here's the Arduino sketch code:

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The sensor generates an interrupt
at a precise angle every revolution.

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The interrupt service routine
calculates RPM.

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Direction is determined
by the phase of the sensor's

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cosine output
at the sine-output edge interrupt.

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We track the RPM change here.

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These are the main things
we used in the demo:

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And here are some of our
design support resources.

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ADT Sensor features include:

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precision;

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wide airgap tolerance;

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low power;

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full temperature range;

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and ultramniature.

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Click, e-mail, or call us
for more information,

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or to order sensors and accessories.