Vernier ACC-BTA Quick Start Manual

25-g Accelerometer
(Order Code ACC-BTA)
The 25-g Accelerometer can be used for a
wide variety of experiments and
demonstrations, both inside the lab and
outside.
Note: Vernier products are designed for
educational use. Our products are not designed nor are they recommended for
any industrial, medical, or commercial process such as life support, patient
diagnosis, control of a manufacturing process, or industrial testing of any kind.

Compatible Software

See
www.vernier.com/manuals/acc-bta
25-g Accelerometer.

Getting Started

1. Connect the sensor to the interface (LabQuest Mini, LabQuest 2, etc.).
2. Start the appropriate data-collection software (Logger Pro, Logger Lite,
LabQuest App, or Graphical Analysis 4) if not already running, and choose
New from File menu. The software will identify the sensor and load a
default data-collection setup. You are now ready to collect data.
If you are collecting data using a Chromebook™, mobile device such as iPad
or Android™ tablet, or a Vernier wireless interface, please see the following
link for up-to-date connection information:
www.vernier.com/start/acc-bta

Calibrating the Sensor

Optional Calibration Procedure

You do not need to calibrate this sensor. Each sensor is calibrated prior to being
shipped to you. The measurement being made by this sensor is complex and can
be difficult to analyze, so be sure to read the Frequently Asked Questions
section below. In most experiments you can simply use the default calibration,
but then use the software's zeroing option and zero the sensor in the appropriate
orientation.
Most accelerometers, including this one, sense gravity as well as acceleration.
This can make results more difficult to understand, but it provides an easy
calibration method. Calibration may be done using the acceleration due to
gravity. To calibrate the sensor for measuring acceleration in the horizontal
direction, position the accelerometer with the arrow pointing down for the first
calibration point. Define this as –9.8 m/s
the arrow points up and use the reading for the second calibration point. Define
2
this as +9.8 m/s or +1g. The accelerometer will then read 0 with no
acceleration when held horizontally. If you want to calibrate for measuring
for a list of software compatible with the
2
or –1g. Rotate the accelerometer so
acceleration in the vertical direction, follow the procedure above, but define the
first calibration point as 0g or 0 m/s

Specifications

Power
Range
Accuracy
Frequency response
12-Bit resolution
Stored calibrations for the 25-g
Accelerometer

Care and Maintenance

Do not wrap the cable tightly around the sensor for storage. Repeatedly doing
so can irreparably damage the wires and is not covered under warranty.

How the Sensor Works

The accelerometer senses acceleration using an integrated circuit (IC) originally
designed to control the release of air bags in an automobile. This IC is micro-
machined with very thin "fingers" carved in silicon. These fingers flex when
®
accelerated. They are arranged and connected like the plates of a capacitor. As
the fingers flex, the capacitance changes, and a circuit included in the IC
monitors the capacitance, converting it into a voltage. The op-amp circuit on
our circuit board amplifies and filters this signal.
The accelerometer measures acceleration along the line marked by the arrow on
the sensor. Accelerations are normally measured in either meters per second per
2
second (m/s ) or g. One g is the acceleration due to gravity at the Earth's
2
surface, or 9.8 m/s
2
of –25g (–250 m/s
acceleration, it is easy to produce accelerations larger than this in collisions. In
fact, dropping the accelerometer on a hard surface from even a few centimeters
can produce accelerations of 100g. The accelerometer will not be damaged by
accelerations up to 1000g.
There is inherent noise in the sensing device inside the accelerometer. This
limits the use in low acceleration environments. The noise is typically on the
2
order of 2.5 m/s peak to peak. Therefore, best results are achieved if the
experiments are designed around magnitudes or changes exceeding 9.8 m/s
The zero will drift with temperature.
1
2
and the second point as 2g or 19.6 m/s
30 mA @ 5 VDC
± 245 m/s
±2.45 m/s
0–100 Hz
0.16 m/s
slope: 127.9 m/s
intercept: –287.9 m/s
. This accelerometer will measure accelerations in the range
2
) to +25g (250 m/s ). Even though this is a fairly large
2
.
2
(±25g)
2
(±0.25g)
2
2
/V
2
2
.