Basic Electrometer
012-07124B
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Figure 1. Electrometer panel controls
Setup Procedure
1. Before turning on the electrometer, check that
the meter reads zero. If not, turn the Mechanical
Zero Adjust screw, located just below the meter
face, until it does.
Operation
The controls on the front panel of the
electrometer are explained in Figure 1.
Whether you’re using the electrometer to
measure voltage, current, or charge, the
following procedure should be followed each
time you turn on the electrometer.
More information on making accurate
measurements is provided in the sections that
follow.
Warning:
1. Never use the electrometer for
measuring potentials more than 100 volts.
2. Never connect the electrometer to an
electrostatics generator, such as a Van de
Graff generator or a Wimhurst machine.
3.
Avoid touching the input leads until you
have grounded yourself to an earth ground.
A person walking across a rug on a cool
dry day can easily acquire a potential of
several thousand volts.
2. Connect the test lead to the input connector of
the electrometer.
3. Connect the ground post of the electrometer to
an earth ground.
4. Push the power button ON. One of the range
switch LEDs will blink twice in quick
succession.
5. To zero the meter, press the ZERO button.
You’re now ready to use the electrometer to
measure charge, current or voltage.
6. Set the range switch to the desired voltage range.
The range setting refers to the voltage input
required to produce a full-scale meter deflection
(e.g., a setting of 30 means that a full scale meter
deflection indicates a voltage of 30 volts).
Important Points for General
Operations:
1. Between measurements, always press the
Zero button to discharge all excess charge from
the electrometer. Shorting the test leads together
is insufficient. There may still be stray charges
within the electrometer circuitry. Note that on
the most sensitive scale (3 volts), the meter may
not return to exactly zero when the Zero button
is pressed. This is normal and will not affect the
accuracy of the reading.
2. DO NOT use the mechanical zero adjust screw
to set the meter to zero, unless power is off.
3. For good results, it is essential that the
electrometer be connected to an earth ground (a
water pipe or the ground wire from a 120 VAC
socket). Only an earth ground provides a
sufficient drain for excess charges that may
build up during an experiment. It is also helpful
if the experimenter is grounded. Just touch one
hand to a good earth ground just before, or
during measurements.
zero button,
ground and
remove excess
charges
select voltage
range
(3,10,30,100V)
output signal
to interface
100 V
mechanical zero
adjust screw
(adjust with
power off)
connect test
lead here
connect to
earth ground
push to turn ON/OFF
meter
display
