Lake Shore Model 421 Gaussmeter User’s Manual
Hall Generator
C-3
C2.3 HANDLING
CAUTION:
Care must be exercised when handling the Hall generator. The Hall generator is
very fragile. Stressing the Hall generator can alter its output. Any excess force
can easily break the Hall generator. Broken Hall generators are not repairable.
Hall Generators are very fragile and require delicate handling. The ceramic substrate used to produce
the Hall Generator is very brittle. Use the leads to move the Hall generator. Do not handle the
substrate. The strength of the lead-to-substrate bond is about 7 ounces, so avoid tension on the leads
and especially avoid bending them close to the substrate. The Hall Generator is also susceptible to
bending and thermal stresses.
C2.4 POLARITY
If the control current enters the red lead (with +I
C
connected to the positive terminal of the current
supply), and the magnetic field direction is as shown in Figure C-2, a positive Hall voltage will be
generated at the blue lead (+V
H
). Reversing either the current or the magnetic field will reverse the
output voltage.
C2.5 LEAD
CONFIGURATIONS
All Hall generators (except Models HGCA-3020 and HGCT-3020) have 34 AWG solid copper with
poly-nylon insulation and have the same lead configuration as follows:
Red = +I
C
Green = I
C
Blue = +V
H
Clear = V
H
Input (Control Current)
}
}
Output (Hall Voltage)
The Model HGCA-3020 and HGCT-3020 Hall generators have 34 AWG stranded copper with Teflon
®
insulation and have the following lead configuration:
Red = +I
C
Black = I
C
Blue = +V
H
Yellow = V
H
Input (Control Current)
}
}
Output (Hall Voltage)
C3.0
HALL GENERATOR GENERIC HOOKUP
The Hall voltage leads may also be connected directly to a readout instrument, such as a high
impedance voltmeter, or can be attached to electronic circuitry for amplification or conditioning.
Device signal levels will be in the range of microvolts to hundreds of millivolts. In this case, a separate
precision current source (Lake Shore Model 120CS or equivalent) is necessary. See Figure C-3.
CAUTION:
The four Hall generator leads connect to four points on a sheet of semiconductor
material having different potentials. No two leads can be connected together
without adversely affecting operation. Therefore, the current source and the output
indicator cannot have a common connection, but must be isolated from each other.
One, the other, but not both, may be grounded.
CAUTION:
Do not exceed the maximum continuous control current given in the specifications.
The Hall generator input is not isolated from its output. In fact, impedance levels on the order of the
input resistance are all that generally exist between the two ports. To prevent erroneous current
paths, which can cause large error voltages, the current supply must be isolated from the output
display or the down stream electronics.
