Products

Hall Generators

Hall Generator Theory

A Hall generator is a solid state sensor which provides an output voltage proportional to magnetic flux density. As implied by its name, this device relies on the Hall effect. The Hall effect is the development of a voltage across a sheet of conductor when current is flowing and the conductor is placed in a magnetic field.

Electrons (the majority carrier most often used in practice) "drift" in the conductor when under the influence of an external driving electric field. When exposed to a magnetic field, these moving charged particles experience a force perpendicular to both the velocity and magnetic field vectors. This force causes the charging of the edges of the conductor, one side positive with respect to the other. This edge charging sets up an electric field which exerts a force on the moving electrons equal and opposite to that caused by the magnetic-field-related Lorentz force. The voltage potential across the width of the conductor is called the Hall voltage. This Hall voltage can be utilized in practice by attaching two electrical contacts to the sides of the conductor. The Hall voltage can be given by the expression:

V_H = γ_B B sin θ

where:

V_H = Hall voltage (mV)
γ_B = Magnetic sensitivity (mV/kG) (at a fixed current)
B = Magnetic field flux density (kilogauss)
θ = Angle between magnetic flux vector and the plane of Hall generator.

As can be seen from the formula, above, the Hall voltage varies with the angle of the sensed magnetic field, reaching a maximum when the field is perpendicular to the plane of the Hall generator.

Hall generators come in two main configurations, axial and transverse.

Transverse Sensors

Transverse devices are generally thin and rectangular in shape. They are applied successfully in magnetic circuit gaps, surface measurements and general open field measurements.

Axial Sensors

Axial sensors are mostly cylindrical in shape. Their applications include ring magnet center bore measurements, solenoids, surface field detection and general field sensing. See the individual Hall generator illustrations for physical dimensions.

Active Area

The Hall generator assembly contains the sheet of semiconductor material to which the four contacts are made. This entity is normally called a "Hall plate." The Hall plate is, in its simplest form, a rectangular shape of fixed length, width and thickness. Due to the shorting effect of the current supply contacts, most of the sensitivity to magnetic fields is contained in an area approximated by a circle, centered in the Hall plate, whose diameter is equal to the plate width. Thus, when the active area is given, the circle as described above is the common estimation.

Using a Hall Generator

A Hall generator is a four lead device. The control current Ic leads are normally attached to a current source such as model 120 CS. The model 120 CS provides several fixed current values compatible with various Hall generators.

Caution: Do not exceed the maximum continuous control current given in the specifications.

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.

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.

Specifications

Axial Hall Generator Specifications

Axial	HGA-2010	HGA-3010	HGA-3030
Description	General purpose axial; high sensitivity	Instrumentation quality axial; low temperature coefficient; phenolic package	Instrumentation quality axial; phenolic package
Active area	0.005" x 0.005" square	0.030" dia. circle	0.030" dia. circle
Input resistance	450 to 900 ohms	1 ohm	2 ohms
Output resistance	550 to 1350 ohms	1 ohm	2 ohms
Nominal control current (ICN)	1 mA	100 mA	100 mA
Maximum continuous current (non-heat sinked)	10 mA	300 mA	300 mA
Magnetic sensitivity (IC = nominal control current)	11 to 28 mV/kG	0.56 to 1.04 mV/kG	6.0 to 10.0 mV/kG
Maximum linearity error (sensitivity versus field)	±1% RDG (-10 to +10 kG) ±2% RDG (-20 to +20 kG)	±1% RDG (-20 to +20 kG) ±1.5% RDG (-100 to +100 kG)	±0.25% RDG (-10 to +10 kG) ±1.00% RDG (-30 to +30 kG)
Zero field offset voltage (IC = nominal control current)	±2.8 mV (max.)	±50 µV (max.)	±75 µV (max.)
Operating temperature range	–20 to 75 °C	–40 to +100 °C	–40 to +100 °C
Mean temperature coefficient of magnetic sensitivity	–0.06%/°C (max.)	±0.005%/°C (max.)	–0.04%/°C (max.)
Mean temperature coefficient of offset (IC = nominal control current)	±1 µV/°C (max.)	±0.4 µV/°C (max.)	±0.3 µV/°C (max.)
Mean temperature coefficient of resistance	+0.15%/°C (approx)	±0.15%/°C (approx)	+0.18%/°C (approx)
Leads	34 AWG copper with poly-nylon insulation	34 AWG copper with poly-nylon insulation	34 AWG copper with poly-nylon insulation
Data	Uncalibrated	Room temperature, 20 kG data supplied	Room temperature, 30 kG data supplied

Transverse Hall Generator Specifications

Transverse	HGT-1010	HGT-2010	HGT-2100	HGT-3010	HGT-3030
Description	General purpose transverse; 0.020" thick	General purpose transverse; high sensitivity	Low cost; high sensitivity; surface mount	Instrumentation quality transverse; low temperature coefficient; ceramic package	Instrumentation quality transverse ceramic package
Active area	0.040" dia. circle	0.005" x 0.005" square	0.005" x 0.005" square	0.040" dia. circle	0.040" dia. circle
Input resistance	2 ohms	450 to 900 ohms	450 to 900 ohms	1 ohm	2 ohms
Output resistance	2 ohms	550 to 1350 ohms	550 to 1350 ohms	1 ohm	2 ohms
Nominal control current (ICN)	100 mA	1 mA	5 mA	100 mA	100 mA
Maximum continuous current (non-heat sinked)	300 mA	10 mA	10 mA	300 mA	300 mA
Magnetic sensitivity (IC = nominal control current)	7.7 to 12.5 mV/kG	11 to 28 mV/kG	55 to 140 mV/kG	0.56 to 1.04 mV/kG	6.0 to 10.0 mV
Maximum linearity error (sensitivity versus field)	±1.0% RDG (-10 to 10 kG)	±1% RDG (-10 to 10 kG) ±2% RDG (-20 to 20 kG)	±1% RDG (-10 to 10 kG) ±2% RDG (-20 to 20 kG)	±1% RDG (-20 to 20 kG) ±1.5% RDG (-100 to 100 kG)	±0.25% RDG (-10 to 10 kG) ±1.00% RDG (-30 to 30 kG)
Zero field offset voltage (IC = nominal control current)	±100 µV (max.)	±2.8 mV (max.)	±14 mV (max.)	±50 µV (max.)	±75 µV (max.)
Operating temperature range	–40 to +100 °C	–20 to +75 °C	–55 to +125 °C	–40 to +100 °C	–40 to +100 °C
Mean temperature coefficient of magnetic sensitivity	–0.08%/°C (max.)	–0.06%/°C (max.)	–0.06%/°C (max.)	±0.005%/°C (max.)	–0.04%/°C (max.)
Mean temperature coefficient of offset (IC = nominal control current)	±1 µV/°C (max.)	±1 µV/°C (max.)	±5 µV/°C (max.)	±0.4 µV/°C (max.)	±0.3 µV/°C
Mean temperature coefficient of resistance	±0.18%/°C (approx)	+0.15%/°C (approx)	+0.15%/°C (approx)	±0.15%/°C (approx)	±0.18%/°C (approx)
Leads	34 AWG copper with poly-nylon insulation	34 AWG copper with poly-nylon insulation	Not applicable	34 AWG copper with poly-nylon insulation	34 AWG copper with poly-nylon insulation
Data	Uncalibrated	Uncalibrated	Uncalibrated	Room temperature, 20 kG data supplied	Room temperature, 30 kG data supplied

Cryogenic Hall Generator Specifications

Cryogenic	HGCA-3020	HGCT-3020
Description	Cryogenic axial; phenolic package	Cryogenic transverse; ceramic package
Active area	0.030" diameter circle	0.040" diameter circle
Input resistance	1 ohms	1 ohms
Output resistance	1 ohms	1 ohms
Nominal control current (ICN)	100 mA	100 mA
Maximum continuous current (non-heat sinked)	300 mA	300 mA
Magnetic sensitivity (IC = nominal control current)	0.56 to 1.04 mV/kG	0.56 to 1.04 mV/kG
Maximum linearity error (sensitivity versus field)	±1.0% RDG (-30 to ±30 kG) ±2.0% RDG (-150 to ±150 kG)	±1.0% RDG (-30 to ±30 kG) ±2.0% RDG (-150 to ±150 kG)
Zero field offset voltage (IC = nominal control current)	±200 µV (max.)	±100 µV (max.)
Operating temperature range	4.2 K to 375 K	–20 to ±75 °C
Mean temperature coefficient of magnetic sensitivity	±0.01%/K (approx)	±0.01%/K (approx)
Mean temperature coefficient of offset (IC = nominal control current)	±0.4 µV/K (max.)	±0.4 µV/K (max.)
Mean temperature coefficient of resistance	±0.6%/K (max.)	±0.6%/K (max.)
Leads	34 AWG copper with teflon insulation	34 AWG copper with teflon insulation
Data	Room temperature, 30 kG data supplied	Room temperature, 30 kG data supplied

Various further models are available. Contact us.