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handling, and fingers often carry small amounts of charge at high potential
that can easily leak through the insulator and affect your reading. The best
way to minimize this is by grounding your fingers, or wearing a grounding
strap on your wrist, to remove any charge before releasing the positive (red)
wire from its ground connection. Start recording data before removing the
lead from ground so you will be aware if any stray charge accumulates
before making your connection. When connecting to static sources (not a
fixed voltage like a battery), the Reset button can be used while connected
to a passive charge receptor. Make sure the output reads zero after reset. If it
does not, re-connect the clips to a common conductor and re-zero the sensor.
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The sensor is not differential; therefore the negative (black) side is always at
ground potential. The supplied cable is shielded and has a low leakage
dielectric. When using other cables, the unit should be tested to make sure
the cable does not allow excessive leakage currents.
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The negative (black) wire is the ground connection. The effects of stray
static charges will be minimized by connecting the black lead to a metal
ground plane below your experiment, such as a sheet of aluminum foil or a
baking pan.
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Synthetic clothing can carry significant charge, as can the experimenter’s
body. Grounding the experimenter by using a ground strap on one wrist will
help. Wearing all cotton clothing can also help.
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When not using a Faraday Pail and ground plane, it helps to connect a metal
cup to the positive (red) wire. This cup adds negligible capacitance to the
system, but makes it easy to see induced or deposited charges. Insulate the
cup from the ground plane using a glass jar or beaker. Plastic does not work
well because it will accumulate stray charge quickly.
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Complete all experiments quickly. Due to leakage currents in the cable and
apparatus, the reading will rarely be reliable after 15 seconds.
Tips for Use with a Faraday Pail and Ground Plane
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Use of this sensor is simplified with the aid of a Faraday pail and ground
plane such as found in the Vernier Electrostatics Kit (ESK-CRG).
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Since the sensor is capable of measuring very small amounts of charge, it is
important to begin experiments by zeroing (resetting) the sensor. Simply
press the Reset (Q=0) button on the sensor for a few seconds to zero the
equipment. (Pressing the Reset button internally shorts the wires, shorts the
internal input capacitor, and the internal integrator capacitor.)
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The sensor should be zeroed after initial power up and before collecting
data.
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During data collection, monitor the sensor reading. If an excess charge
develops on the sensor, zero the sensor prior to a new data-collection run.
Connecting the Sensor
See the following link for up-to-date connection information:
Connecting via Bluetooth
Ready to connect
Red LED next to the Bluetooth icon flashes
when sensor is awake and ready to connect.
Connected
Green LED next to the Bluetooth icon flashes
when sensor is connected via Bluetooth.
Connecting via USB
Connected and charging
Orange LED next to the battery icon is solid
when the sensor is connected to Graphical Ana-
lysis via USB and the unit is charging. LED next
to Bluetooth icon is off.
Connected, fully charged
Green LED next to the battery icon is solid
when the sensor is connected to Graphical Ana-
lysis via USB and fully charged. LED next to
Bluetooth icon is off.
Charging via USB,
connected via Bluetooth
Orange LED next to the battery icon is solid
when the sensor is charging. Green LED next to
the Bluetooth icon flashes.
Identifying the Sensor
When two or more sensors are connected, the sensors can be identified by
tapping or clicking Identify in Sensor Information.
Using the Product
Connect the low leakage BNC/alligator clip cable to the BNC connector on the
sensor body. Prepare the sensor for data collection following the steps in the
Getting Started section of this user manual.
General Tips
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When the sensor is stored, it is a good idea to clip together the wires in
order to protect the sensor from high static potential that could damage the
unit. Press the Reset button (Q = 0) with the red and black wires connected
to a common conductor for a few seconds to zero the sensor.
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Pressing and releasing the Reset button with the clips connected to a voltage
source, such as a power supply or battery, will cause an error in the reading
and is not recommended, because it will short the power supply as well.
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Since the sensor is capable of measuring very small amounts of charge, it is
essential to begin experiments by zeroing the sensor.
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You must be careful when handling the leads or you may alter the readings
with stray charge. The insulator on the clip lead quickly becomes oily from