WEBVTT

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♪ Sensitivity ♪

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Today we're demonstrating the 
extraordinary sensitivity

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of our ALT021 TMR magnetometers

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...using pendulums.

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We set an evaluation board powered by a 
AAA battery next to a Newton's Cradle.

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The sensor is sensitive enough to detect the 
stray magnetic field from the steel balls.

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This is at 5 mV/division...

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2 mV/division...

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...and 1 millivolt,
or about 0.3 µT/division.

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We can still detect a signal 
when the balls are barely moving,

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and the amplitude
is less than 100 nanotesla.

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Here's a closer look at the 
sensor evaluation board.

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It has a sensor
plus a simple differential amplifier.

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We can detect a small magnet
even farther away.

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Here we replace the steel balls 
with a spherical neodymium magnet.

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A tray of water damps the motion,
so we can see what happens

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when the amplitude decreases.

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Without the water,
this demonstration would take a long time.

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The magnet is up to a foot away
from the sensor.

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As you can see, there's still a clear 
signal with the magnet barely moving.

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The amplifier has a gain of five 
for a sensitivity of 2.5 V/V/mT.

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It uses a single op amp.

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The board can be powered
by a 1.5 V battery.

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We added an RC low-pass filter
between the board and the oscilloscope.

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The sensor is extremely sensitive 
even without amplification,

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and can detect fields
as small as 0.1 microtesla.

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It comes in a small package,

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and has a high device resistance to 
draw just 75 microamps at 1.5 volts.

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Use this QR code for more information.