Littelfuse Sensors Catalog

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PRODUCT
CATALOG &
DESIGN GUIDE

Proximity | Level | Speed | Flow

About This Guide
This guide provides an introduction to magnetic sensing and options for value-added
custom design packages. It also offers practical suggestions for selecting reed switches,
reed sensors and Hall effect sensors for a variety of applications.

Topic

Page

Introduction to Magnetic Sensing

2–3

Value-Added Customization

3

Reed Switches

4–5

Hall Effect Sensors

7

Reed Sensors

8–9

Reed Relays

10

Magnetic Actuators

11

Applications

12–15

WHY CHOOSE LITTELFUSE
Littelfuse, Inc. is the global leader in circuit protection solutions. Our
company offers the broadest spectrum of circuit protection technologies
along with products that can be used in any application that requires
electrical energy.
Complementing our vast portfolio of circuit protection products is
a global network of technical support and design expertise. Using
our decades of design experience, we help you address unique
application challenges and achieve regulatory compliance.

59135
(High-Temperature Flange Mount
Reed Sensor)

Your Single Source
Littelfuse offers the world’s most diverse and extensive circuit protection
product line. If we do not have an off-the-shelf product to meet your needs,
we will work with you to develop a forward-thinking solution that precisely
fits your application. Our goal is to provide the most comprehensive range
of options so that you will not have to make compromises in your designs.

Testing Support
Through our network of Global Labs located in China, Germany,
Japan, Mexico, Philippines and the U.S., we design innovative circuit
protection solutions and provide customer application support and testing.
Our unique capabilities include performance testing, material analysis and
regulatory compliance testing. The dedication of our Global Labs ensures
the outstanding performance, safety and reliability of our products
and support services for our worldwide customer base.

59010
(Ultra-Mini Firecracker)

Application Knowledge
At Littelfuse, our expertise involves applying reliable and efficient circuit
protection solutions, innovative technologies and global resources to
address circuit protection challenges in a variety of applications. We utilize
a worldwide network of research teams that focus on product development
and support, design-in programs and application testing in our Global Labs.

MDCG-4
(Reed Switch)

Global Support
Littelfuse products, application knowledge and technical support are
available around the globe. We offer a network of regional customer
support offices and hundreds of authorized distributors to assist
you with your circuit protection requirements.

WHY CHOOSE LITTELFUSE SENSORS
Hamlin, now part of Littelfuse, Inc., has a long, rich history of leading
the industry in providing magnetic sensing solutions. Our experts
are committed to delivering the best products and solutions
for your specific needs.

59050
(Overmolded Reed Switch)

Our global organization provides:
• Custom sensor designs per customer specifications
• Vertically integrated manufacturing
• In-house magnetic simulation support
• Quick turnaround for custom sensor prototypes

Quality Assurance
Our global manufacturing facilities abide by strict quality
assurance requirements and hold the following quality
management system registrations:
55140
(Flange Mount
Hall Effect Sensor)

Littelfuse electronics product portfolio includes Hamlin

hamlin.com | littelfuse.com

1

Introduction to
Magnetic Sensing
Reed Switches
A reed switch has two ferromagnetic blades (reeds) contained within a tubular glass envelope that
is hermetically sealed at each end. The contacts on each reed blade have a thin layer of precious metal
material deposited on them. There is usually nitrogen gas on the inside of the glass envelope to eliminate
the presence of oxygen and ensure that the contacts will not oxidize. Reed switches are activated
by a permanent magnet or an electromagnet. The reed switch and magnetic field combination
is commonly known as the “magnetic circuit.”

S

N

N

N

S

The relative stiffness of the
reed blades
along with the
S
N
N
small gap and overlap between
the two contacts controls the
sensitivity of the reed switch.
The sensitivity of the switch is
the amount of magnetic field
that is required to actuate the
contact an open or closed
mode. It is measured in
S
N
units of ampere-turns (AT).
Most reed switches have a
sensitivity range of 10–30 AT,
where 10 AT is more sensitive
than 30 AT.

Y
mm

S

Hold

OPEN

Hold

Close

X
mm

Y

MAGNET

N

N

MAGNET

S

-X

X

Figure 2-Two-pole linear activation,
parallel orientation

Close

O

-X
mm

OPEN

Hold

Close

O

-X
mm

Y
mm

OPEN

X
mm

Y

S

-X

X

Figure 3-Single-pole linear activation,
perpendicular orientation

Reed Sensors
S

N

S

Figure 1-Magnetic field lines
must be aligned parallel to a
reed switch’s contacts in order
to open/close the contacts

Reed sensors are reed switches that are packaged within an external housing for simplified mounting/
connecting and additional protection against environmental influences. These sensors are typically
mounted in mechanical systems. A bare reed switch can easily be mounted on circuit boards. However,
for an application such as a door security sensor, the reed switch needs a protective shell/housing
for handling and mounting. These packages offer resistance to mechanical stress by protecting
the bare glass of the reed switch.

Reed Relays
A reed relay is made by combining a reed switch with a copper coil. Like other relays, this provides
galvanic isolation between the coil input and the controlled contact(s). However, because of the small size
and magnetic efficiency of the reed switch, the power required to drive the coil is lower than most other
types of relays. Other advantages include high insulation resistance, low contact resistance and long
contact life. Reed relays are used in many applications, including automotive, test equipment, security,
medical and process control equipment.

Reed
Switch
Comparing Reed vs. Hall Effect
Although there are differences
between reed switch and
Hall effect technologies,
both platforms offer practical
advantages for various
applications. Here is a
comparison of the benefits
of each technology.

2

Littelfuse electronics product portfolio includes Hamlin

•
•
•

Hall Effect
Sensor
Noncontact sensing element

•

Zero power consumption
High-Frequency operation

•

Digital switching

•

Linear sensing

•

Integrated circuitry

•

Ultra-small package size

•

•

Electrical load capability

•

EMC/ESD immunity

Hall Effect Sensors
A Hall effect device is a semiconductor-based integrated circuit with Hall plates that respond to
magnetic fields. Additional circuitry is added for power supply and signal conditioning, temperature
compensation and EMC/ESD protection. Hall effect devices provide digital or analog output signals that
are used for proximity and continuous rotary or linear positioning. Unlike a reed switch, a Hall effect
device contains active circuitry, so it draws a small amount of current at all times. Hall effect devices
come in two- or three-wire versions. Some devices are programmable.

Magnetic Actuators
Littelfuse offers a wide range of magnetic actuators that are packaged in shapes similar to the relative
mating sensors. We also offer a limited family of bare magnets with various grades of materials,
including ferrite (ceramic), AlNiCo and neodymium iron boron (NdFeB) materials.

Value-Added Customization
Littelfuse specializes in custom design packages that meet our customers’ needs for both reed
and Hall effect sensor designs. Several of our vertically integrated processes are listed below.

Joining/Sealing Methods
• Ultrasonic welding
• Heat staking

Encapsulation
• Transfer overmold
• Low-pressure overmold
• Epoxy/urethane
• Meter/mix dispensing

Assembly Methods
• Automated
• Cellular
• Manual

100% End of Line Testing
• Hermetic seal test
• Magnetic actuation
• Contact resistance
Circuit Board Assembly
• Vision systems
• In-circuit test
• Pick and place
• Reflow
• Wave
• Robotic

Custom Magnet Solutions
• Magnetic simulation and modeling
for customer-specific designs
• Integral magnets within the sensor
• Magnetic circuits with tight
tolerances available

PACK

Terminations
• Injection molding
• Insert molding
• Automatic cut, strip
and crimp
• Littelfuse applies many
customer-specified
connectors

Reed Switch and Hall Effect
• Automatic switch assembly machines
• Custom reed switch forming equipment
• Automated testing
• Automatic cut and form
• Tape & reel packaging for SMD and other 		
custom design requirements

hamlin.com | littelfuse.com

3

Reed Switches

Power

Size

Terminals

Leads
Small

Switch Type

Package

P/N

Body Length
(mm)/[Inch]

Total Length
(mm)/[Inch]

A: SPST-NO

Glass

MITI-7

7.00 [.276]

40.38 [1.590]

A: SPST-NO

Glass

MDSR-10

10.16 [.400]

40.38 [1.590]

A: SPST-NO

Glass

MDSR-7

12.70 [.500]

40.38 [1.590]

A: SPST-NO

Glass

MISM-7

7.00 [.276]

13.72 [.540]

A: SPST-NO

Glass

MDSM-10

10.16 [.400]

15.62 [.615]

A: SPST-NO

Glass

FLEX-14

14.00 [.551]

44.30 [1.744]

A: SPST-NO

Glass

MDCG-4

15.24 [.600]

40.38 [1.590]

A: SPST-NO

Glass

MACD-14

14.00 [.551]

44.30 [1.744]

C: SPDT-CO

Glass

MDRR-DT

14.73 [.580]

51.66 [2.034]

A: SPST-NO

Glass

MDSM-4

15.24 [.600]

19.30 [.760]

A: SPST-NO

Glass

MASM-14

14.00 [.551]

44.30 [1.744]

C: SPDT-CO

Glass

MDSM-DT

14.73 [.580]

25.40 [1.00]

A: SPST-NO

Overmolded

59165

16.00 [.630]

20.20 [.795]

A: SPST-NO

Overmolded

59166

16.00 [.630]

19.51 [.768]

A: SPST-NO

Overmolded

59170

11.43 [.450]

16.25 [.640]

A: SPST-NO

Overmolded

59045-1

17.78 [.700]

15.24 [.600]

A: SPST-NO

Overmolded

59050-1

22.86 [.900]

20.32 [.800]

A: SPST-NO

Glass

HA15-2

15.24 [.600]

40.38 [1.590]

A: SPST-NO

Glass

MLRR-4

15.24 [.600]

40.38 [1.590]

A: SPST-NO

Glass

MLRR-3

15.24 [.600]

56.64 [2.230]

A: SPST-NO

Glass

MARR-5

19.69 [.775]

56.77 [2.235]

A: SPST-NO

Glass

MLSM-4

15.24 [.600]

19.56 [.770]

A: SPST-NO

Glass

MLSM-3

15.24 [.600]

19.56 [.770]

A: SPST-NO

Overmolded

59050-2

22.86 [.900]

20.32 [.800]

A: SPST-NO

Glass

MRPR-3

19.69 [.775]

56.64 [2.230]

A: SPST-NO

Glass

MRPR-8

20.32 [.800]

56.64 [2.230]

A: SPST-NO

Glass

DRR-129

50.80 [2.000]

82.55 [3.250]

C: SPDT-CO

Glass

DRR-DTH

39.67 [1.562]

85.73 [3.375]

C: SPDT-CO

Glass

DRT-DTH

39.67 [1.562]

85.73 [3.375]

SMD

MACD-14

Leads

Low Power

SMD

MITI-7

Medium

Both Leads
and SMD

MDSM-4
Leads

Leads

Medium
SMD

DRR-DTH

High Power
Leads

Leads
Large

4

Littelfuse electronics product portfolio includes Hamlin

Notes:
For details on electrical specifications, visit hamlin.com
A:SPST-NO - Single Pole Single Throw - Normally Open
C:SPDT-CO - Single Pole Double Throw - Changeover

Switching
Power (W)

Switching
Voltage (V)

Switching
Current (A)

Contact
Resistance (Ω)

Operating
Temperature (°C)

Magnetic
Sensitivity (AT)

10

170 Vdc, 120 Vac

0.25 Adc, 0.18 Aac

0.15

-40 to +125

6-20

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.12

-40 to +125

10-25

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.1

-40 to +125

10-25

RoHS

10

170 Vdc, 120 Vac

0.25 Adc, 0.18 Aac

0.15

-40 to +125

6-20

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.12

-40 to +125

10-25

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.1

-40 to +125

10-30

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.1

-40 to +125

12-38

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.1

-40 to +125

10-30

RoHS

5

175 Vdc, 120 Vac

0.25 Adc, 0.18 Aac

0.1

-40 to +125

15-30

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.1

-40 to +125

12-38

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.1

-40 to +125

10-30

RoHS

5

175 Vdc, 120 Vac

0.25 Adc, 0.18 Aac

0.1

-40 to +125

15-30

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.1

-40 to +125

10-25

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.1

-40 to +125

10-26

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.15

-40 to +125

10-25

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.2

-40 to +105

15-30

RoHS

10

200 Vdc, 140 Vac

0.5 Adc, 0.35 Aac

0.2

-40 to +105

12-33

RoHS

20

200 Vdc, 265 Vac

0.5 Adc, 0.35 Aac

0.1

-20 to +125

17-38

RoHS

20

200 Vdc, 140 Vac

1.0 Adc, 0.7 Aac

0.1

-40 to +125

17-38

RoHS

20

200 Vdc, 140 Vac

1.0 Adc, 0.7 Aac

0.1

-40 to +125

17-38

RoHS

10

1000 Vdc, 700 Vac

0.5 Adc, 0.35 Aac

0.1

-75 to +125

17-38

RoHS

20

200 Vdc, 140 Vac

1.0 Adc, 0.7 Aac

0.1

-40 to +125

17-38

RoHS

20

200 Vdc, 140 Vac

1.0 Adc, 0.7 Aac

0.1

-40 to +125

17-38

RoHS

20

200 Vdc, 265 Vac

0.5 Adc, 0.35 Aac

0.2

-20 to +105

17-33

RoHS

50

200 Vdc, 140 Vac

1.5 Adc, 1.1 Aac

0.1

-40 to +125

22-43

RoHS

50

250 Vdc, 265 Vac

1.0 Adc, 0.7 Aac

0.1

-20 to +125

22-43

RoHS

100

400 Vdc, 280 Vac

3.0 Adc, 2.1 Aac

0.1

-40 to +125

42-83

RoHS

30

500 Vdc, 350 Vac

0.5 Adc, 0.35 Aac

0.125

-20 to +125

50-80

RoHS

50

500 Vdc, 350 Vac

1.5 Adc, 1.0 Aac

0.5

-20 to +125

50-80

RoHS

Certification

RoHS
Compliance

MDSM-DT

59165

59045

MRPR-3

Lead Modifications
Littelfuse can cut and/or form the reed switch leads to meet your dimensional
requirements. Most lead modifications can be done by Littelfuse without
any additional tooling costs.

hamlin.com | littelfuse.com

5

Sensors,
Reed Relays
and Magnetic
Actuators
Our reed switch, Hall effect sensor and reed sensor products are ideally suited for
various sensing applications, including proximity, level, speed and flow, as shown
in the table. Customizations, including various connectors and wire lengths,
are available for all our standard products. For product specifications
and available options, refer to the individual product datasheets.

Sensor Type
Reed Switches

Application
Proximity

Level

Speed

Flow

•

•

•

•

•

•

Hall Effect Sensors
Flat Pack

•

Round Flange Mount
Flat Flange Mount

•
•

•

Threaded Barrel
Vane

•

•
•

•

Rotary/Angular

•

Reed Sensors
Firecracker

•

•

•

Threaded Barrel

•

•

•

Flange/Flat Pack

•

•

•

Float

6

•

•

Vane

•

Lever Arm

•

Seat Occupancy

•

Littelfuse electronics product portfolio includes Hamlin

•

Hall Effect Sensors
FLAT PACK
This sensor’s rectangular package is ideally suited for mounting on a flat surface.
It is designed for use in a wide range of environments.

Product
Series

55140

Operating
Supply
Voltage

Operating
Supply
Current
mA

LxWxH

Vdc

Max.

Flange Mount Hall, 2-Wire

23.00 (0.906) x 14.00 (0.551) x 6.00 (0.236)

3.75 to 24

N/A

Overall Dimensions
Description

mm (inch)

Output
Type
Current

Flange Mount Hall, 3-Wire

23.00 (0.906) x 14.00 (0.551) x 6.00 (0.236)

3.8 to 24

N/A

Voltage

Flange Mount Hall, Analog

23.00 (0.906) x 14.00 (0.551) x 6.00 (0.236)

4.5 to 5.5

N/A

55300

Flat Pack Rotary Hall

28.50 (1.122) x 20.40 (0.803) x 6.35 (0.250)

4.5 to 5.5

16

55310

Flat Pack Digital Hall

28.50 (1.122) x 20.40 (0.803) x 6.35 (0.250)

4.75 to 24

6

55320

Flat Pack Linear Hall

28.50 (1.122) x 20.40 (0.803) x 6.35 (0.250)

4.5 to 5.5

16

Analog Voltage
Analog Voltage
or PWM
Current
Analog Voltage
or PWM

Output
High

Output
Low

Temperature Rating
˚C

Max.

Operating

Storage

N/A
Sinking/Open
Collector
4.65 V

2.2 - 5.6 mA

-40 to +100

-65 to +105

0.4 V @ 20 mA

-40 to +100

-65 to +105

0.35 V

-40 to +100

-65 to +105

4.5 V

0.5 V

-40 to +105

-65 to +105

N/A

20 mA
-8 to +8 mA
0.5 to 4.5 V

-40 to +105

-65 to +105

-40 to +105

-65 to +125

N/A

ROUND FLANGE MOUNT
Its cylindrical package has a flat flange to accommodate mounting on a flat surface.
This sensor is ideally suited for sensing a rotating ferrous metal target.
Overall Dimensions

Product
Series

Description

55505

Flange Mount Geartooth Hall

mm (inch)
LxWxH
17.86 (0.703) x 36.75 (1.447) x 41.40
(0.551)

Operating
Supply
Voltage
Vdc

Operating
Supply
Current
mA

Output
Type

Output
High

4.75 to 24

N/A

Digital

Vdd-2

Output
Low
Max.
0.6 V @ 20
mA

Temperature Rating
˚C
Operating

Storage

-40 to +125

-65 to +125

FLAT FLANGE MOUNT
The low-profile, rectangular package is designed for installation in small-gap spaces.

LxWxH

Operating
Supply
Voltage
Vdc

Operating
Supply
Current
mA

Output
Type

Output
High

Miniature Flange Mount Hall, 2-Wire

25.50 (1.004) x 11.00 (0.433) x 3.00 (0.118)

3.75 to 24

N/A

Current

N/A
Sinking/Open
Collector
4.65 V

Overall Dimensions
Product
Series

55100
55110

mm (inch)

Description

Miniature Flange Mount Hall, 3-Wire

25.50 (1.004) x 11.00 (0.433) x 3.00 (0.118)

3.8 to 24

N/A

Voltage

Miniature Flange Mount Hall, Analog

25.50 (1.004) x 11.00 (0.433) x 3.00 (0.118)

4.5 to 5.5

N/A

Analog Voltage

LED Flange Mount Hall

34.00 (1.399) x 14.00 (0.551) x 10.00 (0.394)

3.8 to 24

N/A

Voltage

Output
Low

Temperature Rating
˚C

Max.

Operating

Storage

N/A

-40 to +100

-65 to +105

0.4 V @ 10 mA

-40 to +100

-65 to +105

0.35 V

-40 to +100

-65 to +105

-40 to +85

-65 to +85

Vdd-2 @ 0.1 mA 0.4 V @ 20 mA

VANE
This sensor is packaged with a magnet and a Hall effect sensing element.
It is typically used in applications with a moving ferrous metal part.

LxWxH

Operating
Supply
Voltage
Vdc

Operating
Supply
Current
mA

Out put
Type

Output
High

28.00 (1.102) x 13.50 (0.531) x 9.00 (0.354)

3.8 to 24

N/A

Voltage

Sinking/Open
Collector

Overall Dimensions
Product
Series

Description

55085

Miniature Vane, PCB Mount, Hall

mm (inch)

Output
Low

Temperature Rating
˚C

Max.

Operating

Storage

0.4 V @ 20 mA

-40 to +100

-65 to +105

THREADED BARREL
Designed for harsh environments, this sensor may easily be mounted and adjusted
using the supplied retaining nuts. Its cylindrical package is available with metric threads.

Thread Pitch x L

Operating
Supply
Voltage
Vdc

Operating
Supply
Current
mA

Output
Type

Output
High

M12 x 1 Pitch x 46.00 (1.811)

4.75 to 25.2

N/A

Digital

Vdd - 2

Overall Dimensions
Product
Series

Description

55075

Stainless Steel M12 Geartooth Hall

mm (inch)

Output
Low

Temperature Rating
˚C

Max.

Operating

Storage

0.6 V @ 20 mA

-40 to +85

-65 to +85

ROTARY/ANGULAR
This sensor is packaged with a magnet and a Hall effect sensing element.
It provides instantaneous angular position measurement.
Overall Dimensions
Product
Series
55250

Description

mm (inch)
LxWxH

Rotary Hall

50.00 (1.968) x 37.30 (1.469) x 28.25 (1.112)

Operating
Supply
Voltage
Vdc
4.5 to 5.5

Operating
Supply
Current
mA

Output
Type

Output
High

16

Analog Voltage
or PWM

4.5 V

Output
Low

Temperature Rating
˚C

Max.

Operating

Storage

0.5 V

-40 to +125

-65 to +125

hamlin.com | littelfuse.com

7

Sensors, Reed Relays and Magnetic Actuators (continued)

Reed Sensors
FIRECRACKER
This sensor offers a slim, cylindrical package that is suitable for mounting on a frame.

Product
Series

Description

mm (inch)

Contact
Rating
W

Switching
Voltage
Vdc

Breakdown
Voltage
Vdc

Switching
Current
A

Contact
Resistance, Initial
Ohms

ØxL

Max.

Max.

Min.

Max.

Max.

59010

Ultra-Mini Firecracker

3.13 (0.123) x 9.00 (0.354)

10

170

175

0.25

0.25

57020

59020

Mini Firecracker

5.10 (0.201) x 15.24 (0.600)

10

170

175

0.25

0.25

57020

59021

Aluminum Mini Firecracker

5.10 (0.201) x 15.24 (0.600)

10

170

175

0.25

0.25

57020

Firecracker, Normally Open

6.22 (0.245) x 25.40 (1.000)

10

200

250

0.5

0.2

Firecracker, Normally Open High Voltage

6.22 (0.245) x 25.40 (1.000)

10

300

450

0.5

0.2

Firecracker, Changeover

6.22 (0.245) x 25.40 (1.000)

5

175

200

0.25

0.2

Firecracker, Normally Closed

6.22 (0.245) x 25.40 (1.000)

5

175

200

0.25

0.2

Firecracker, Normally Open

6.22 (0.245) x 38.10 (1.500)

10

200

250

0.5

0.2

Firecracker, Normally Open High Voltage

6.22 (0.245) x 38.10 (1.500)

10

300

450

0.5

0.2

Firecracker, Changeover

6.22 (0.245) x 38.10 (1.500)

5

175

200

0.25

0.2

Firecracker, Normally Closed

6.22 (0.245) x 38.10 (1.500)

5

175

200

0.25

0.2

59025

59030

Overall Dimensions

Mating
Actuator

57025

57030

FLOAT
Designed for liquid-level sensing applications, this sensor has an integral float
magnet and a reed switch.

Product
Series

59630

59300

mm (inch)

Contact
Rating
W

Switching
Voltage
Vdc

Breakdown
Voltage
Vdc

Switching
Current
A

Contact
Resistance, Initial
Ohms

ØxL

Max.

Max.

Min.

Max.

Max.

23.70 (0.930) x 43.70 (1.720)

10

200

250

0.5

0.2

23.70 (0.930) x 43.70 (1.720)

10

300

450

0.5

0.2

Float Sensor, Changeover

23.70 (0.930) x 43.70 (1.720)

5

175

200

0.25

0.2

Float Sensor, Normally Closed

23.70 (0.930) x 43.70 (1.720)

5

175

200

0.25

0.2

Level Sensor, Normally Open (Float Not Included)

19.90 (0.783) x 67.55 (2.660)

10

200

250

0.5

0.2

Overall Dimensions
Description
Float Sensor, Normally Open
Float Sensor, Normally Open High Voltage

VANE
Packaged with a magnet and a reed switch, this sensor is typically used in applications
with a moving ferrous metal part.

Product
Series

59085

59090

mm (inch)

Contact
Rating
W

Switching
Voltage
Vdc

Breakdown
Voltage
Vdc

Switching
Current
A

Contact
Resistance, Initial
Ohms

LxWxH

Max.

Max.

Min.

Max.

Max.

25.40 (1.000) x 19.05 (0.750) x 6.35 (0.250)

5

175

200

0.25

0.2

25.40 (1.000) x 19.05 (0.750) x 6.35 (0.250)

5

175

200

0.25

0.2

Vane Sensor, Normally Closed

25.40 (1.000) x 19.05 (0.750) x 6.35 (0.250)

10

200

250

0.5

0.2

Vane Sensor, Normally Closed High Voltage

25.40 (1.000) x 19.05 (0.750) x 6.35 (0.250)

10

300

450

0.5

0.2

Heavy Duty Vane Sensor, Normally Closed

32.50 (1.280) x 32.25 (1.271) x 23.25 (0.915)

10

200

250

0.5

0.2

Heavy Duty Vane Sensor, Normally Closed High Voltage

32.50 (1.280) x 32.25 (1.271) x 23.25 (0.915)

10

300

450

0.5

0.2

Heavy Duty Vane Sensor, Changeover

32.50 (1.280) x 32.25 (1.271) x 23.25 (0.915)

5

175

200

0.25

0.2

Overall Dimensions
Description
Vane Sensor, Normally Open
Vane Sensor, Changeover

SEAT OCCUPANCY
Packaged with an integral magnet and a reed switch, this sensor is available in
a push-button configuration or a dome configuration for weight/load distribution.

mm (inch)

Contact
Rating
W

Switching
Voltage
Vdc

Breakdown
Voltage
Vdc

Switching
Current
A

Contact
Resistance, Initial
Ohms

LxWxH

Max.

Max.

Min.

Max.

Max.

32.51 (1.280) x 26.67 (1.050) x 37.34 (1.470)

10

200

250

0.5

0.2

10

200

250

0.5

0.2

Overall Dimensions

Product
Series

Description

59250

Push-button Seat Sensor (Reed)

59251

Seat Sensor with Dome (Reed)

108.20 (4.260) x 69.85 (2.750) x 39.88 (1.570)

8

Littelfuse electronics product portfolio includes Hamlin

THREADED BARREL
Designed with a cylindrical package, this sensor is available with English and metric threads.
It may easily be mounted and adjusted using the supplied retaining nuts.

Product
Series

59060

59065

59070

59075

Description

mm (inch)

Contact
Rating
W

Thread Pitch x L

Max.

Max.

Min.

Max.

Max.

Stainless Steel Threaded Barrel Sensor, Normally Open

M8 x 1.25 Pitch x 36.00 (1.420)

10

200

250

0.5

0.2

Stainless Steel Threaded Barrel Sensor, Normally Open High Voltage

M8 x 1.25 Pitch x 36.00 (1.420)

10

300

450

0.5

0.2

Stainless Steel Threaded Barrel Sensor, Changeover

M8 x 1.25 Pitch x 36.00 (1.420)

5

175

200

0.25

0.2

Stainless Steel Threaded Barrel Sensor, Normally Closed

M8 x 1.25 Pitch x 36.00 (1.420)

5

175

200

0.25

0.2

Overall Dimensions

Switching
Voltage
Vdc

Breakdown
Voltage
Vdc

Switching
Current
A

Contact
Resistance, Initial
Ohms

Threaded Barrel Sensor (Standard), Normally Open

(5/16 x 24) Pitch x 38.10 (1.500)

10

200

250

0.5

0.2

Threaded Barrel Sensor (Standard), Normally Open High Voltage

(5/16 x 24) Pitch x 38.10 (1.500)

10

300

450

0.5

0.2

Threaded Barrel Sensor (Standard), Changeover

(5/16 x 24) Pitch x 38.10 (1.500)

5

175

200

0.25

0.2

Threaded Barrel Sensor (Standard), Normally Closed

(5/16 x 24) Pitch x 38.10 (1.500)

5

175

200

0.25

0.2

Threaded Barrel Sensor (Metric), Normally Open

M8 x 1.25mm Pitch x 38.10 (1.500)

10

200

250

0.5

0.2

Threaded Barrel Sensor (Metric), Normally Open High Voltage

M8 x 1.25mm Pitch x 38.10 (1.500)

10

300

450

0.5

0.2

Threaded Barrel Sensor (Metric), Changeover

M8 x 1.25mm Pitch x 38.10 (1.500)

5

175

200

0.25

0.2

Threaded Barrel Sensor (Metric), Normally Closed

M8 x 1.25mm Pitch x 38.10 (1.500)

5

175

200

0.25

0.2

Heavy Duty Threaded Barrel, Normally Open

M12 x 1mm Pitch x 46.00 (1.810)

10

200

250

0.5

0.2

Heavy Duty Threaded Barrel, Normally Open High Voltage

M12 x 1mm Pitch x 46.00 (1.810)

10

300

450

0.5

0.2

Heavy Duty Threaded Barrel, Changeover

M12 x 1mm Pitch x 46.00 (1.810)

5

175

200

0.25

0.2

Heavy Duty Threaded Barrel, Normally Closed

M12 x 1mm Pitch x 46.00 (1.810)

5

175

200

0.25

0.2

Mating
Actuator

57060

57065

57070

57075

FLANGE/FLAT PACK
This sensor offers a rectangular package that is designed for mounting on a flat surface.
It is suitable for use in a wide range of environments, including high-temperature applications.

Product
Series

59105

59125

59135

59140

59141

59145

59150

Description

mm (inch)

Contact
Rating
W

LXWXH

Max.

Max.

Min.

Max.

Max.

Terminal Flange Mount Sensor, Normally Open

40.17 (1.582) x 19.05 (0.750) x 6.60 (0.260)

10

200

250

0.5

0.2

Terminal Flange Mount Sensor, Normally Open High Voltage

40.17 (1.582) x 19.05 (0.750) x 6.60 (0.260)

10

300

450

0.5

0.2

Terminal Flange Mount Sensor, Normally Closed

40.17 (1.582) x 19.05 (0.750) x 6.60 (0.260)

5

175

200

0.25

0.2

Overall Dimensions

Switching
Voltage
Vdc

Breakdown
Voltage
Vdc

Switching
Current
A

Contact
Resistance, Initial
Ohms

Pinned Flange Mount Sensor, Normally Open

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

10

200

250

0.5

0.2

Pinned Flange Mount Sensor, Normally Open High Voltage

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

10

300

450

0.5

0.2

Pinned Flange Mount Sensor, Normally Closed

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

5

175

200

0.25

0.2

High-Temp Flange Mount Sensor, Normally Open

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

10

200

250

0.5

0.2

High-Temp Flange Mount Sensor, Normally Open High Voltage

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

10

300

450

0.5

0.2

High-Temp Flange Mount Sensor, Changeover

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

5

175

200

0.25

0.2

High-Temp Flange Mount Sensor, Normally Closed

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

5

175

200

0.25

0.2

Mini Flange Mount Sensor, Normally Open

23.0 (0.906) x 14.00 (0.551) x 6.00 (0.236)

10

200

250

0.5

0.2

Mini Flange Mount Sensor, Normally Open High Voltage

23.0 (0.906) x 14.00 (0.551) x 6.00 (0.236)

10

300

450

0.5

0.2

Mini Flange Mount Sensor, Changeover

23.0 (0.906) x 14.00 (0.551) x 6.00 (0.236)

5

175

200

0.25

0.2

Mini Flange Mount Sensor, Normally Closed

23.0 (0.906) x 14.00 (0.551) x 6.00 (0.236)

5

175

200

0.25

0.2

Mini Flange Mount Sensor, Normally Open

23.0 (0.906) x 14.00 (0.551) x 6.00 (0.236)

10

200

250

0.5

0.2

Mini Flange Mount Sensor, Normally Open High Voltage

23.0 (0.906) x 14.00 (0.551) x 6.00 (0.236)

10

300

450

0.5

0.2

Mini Flange Mount Sensor, Changeover

23.0 (0.906) x 14.00 (0.551) x 6.00 (0.236)

5

175

200

0.25

0.2

Mini Flange Mount Sensor, Normally Closed

23.0 (0.906) x 14.00 (0.551) x 6.00 (0.236)

5

175

200

0.25

0.2

Flange Mount Sensor, Normally Open

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

10

200

250

0.5

0.2

Flange Mount Sensor, Normally Open High Voltage

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

10

300

450

0.5

0.2

Flange Mount Sensor, Changeover

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

5

175

200

0.25

0.2

Flange Mount Sensor, Normally Closed

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

5

175

200

0.25

0.2

Flange Mount Sensor, Normally Open

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

10

200

250

0.5

0.2

Flange Mount Sensor, Normally Open High Voltage

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

10

300

450

0.5

0.2

Flange Mount Sensor, Changeover

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

5

175

200

0.25

0.2

Flange Mount Sensor, Normally Closed

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

5

175

200

0.25

0.2

Mating
Actuator

57105

57125

57135

57140

57140

57145

57150

LEVER ARM
This clip frame sensor with a lever arm is ideally suited for paper-path sensing
and security system applications.

mm (inch)

Contact
Rating
W

Switching
Voltage
Vdc

Breakdown
Voltage
Vdc

Switching
Current
A

Contact
Resistance, Initial
Ohms

LxWxH

Max.

Max.

Min.

Max.

Max.

24 (0.945) x 23 (0.906) x 10 (0.394)

10

200

250

0.5

0.2

Overall Dimensions

Product
Series

Description

59210

Lever Arm Sensor

hamlin.com | littelfuse.com

9

Sensors, Reed Relays and Magnetic Actuators (continued)

Reed Relays

DUAL-IN-LINE (DIL)
Reed relay products are available in standard dual-in-line packages for mounting
on a printed circuit board or socket.
Overall Dimensions
Product
Series

Description

Reed Relay, DIL, SPST-NO

mm (inch)

Vdc

Vdc

Ohms

Vdc

A

W

LxWxH

LxWxH

Nominal

Max.

Nominal

Max.

Max.

Max.

5

12

500

12

31

1000

200

0.5

10

Form A

24

46

2150
200

0.5

10

Form B

175

0.25

5

Form C

175

0.25

5

Form C

175

0.25

5

Form C

200

0.5

10

Form A

300

0.5

10

Form A

39.50 (0.768) x 7.22 (0.284) x 5.50 (0.217)

20.14 (0.793) x 7.62 (0.300) x 5.82 (0.229)

HE721B0500
Reed Relay, DIL, SPST-NC

39.50 (0.768) x 7.22 (0.284) x 5.50 (0.217)

20.14 (0.793) x 7.62 (0.300) x 5.82 (0.229)

HE721B2400
HE721C0500
HE721C1200

Reed Relay, DIL, SPDT-CO

39.50 (0.768) x 7.22 (0.284) x 5.50 (0.217)

20.14 (0.793) x 7.62 (0.300) x 5.82 (0.229)

HE721C2400
HE721E0500
HE721E1200

Reed Relay, DIL, SPDT-CO

39.50 (0.768) x 7.22 (0.284) x 5.50 (0.217)

20.14 (0.793) x 7.62 (0.300) x 5.82 (0.229)

HE721E2400
HE721R0500
HE721R1200

Reed Relay, DIL, SPDT-CO

39.50 (0.768) x 7.22 (0.284) x 5.50 (0.217)

20.14 (0.793) x 7.62 (0.300) x 5.82 (0.229)

HE721R2400
HE722A0500
HE722A1200

Reed Relay, DIL, DPST-NO

39.50 (0.768) x 7.22 (0.284) x 5.50 (0.217)

20.14 (0.793) x 7.62 (0.300) x 5.82 (0.229)

HE722A2400
HE751A0500
HE751A1200
HE751A2400

Reed Relay, DIL, SPST-NO,
High Voltage

Contact Ratings, Switching

mm (inch)

HE721A2400
HE721B1200

Coil
Resistance

External Shield Body

HE721A0500
HE721A1200

Coil Voltage

Transfer Molded Body

39.50 (0.768) x 7.22 (0.284) x 5.50 (0.217)

20.14 (0.793) x 7.62 (0.300) x 5.82 (0.229)

5

6.5

500

12

14

1000

24

28

2150
200

5

14

12

22

500

24

44

2000
200

5

14

12

22

500

24

44

2000
200

5

14

12

22

500

24

44

2000
200

5

12

12

22

500

24

46

2000

5

12

500

12

21

1000

24

46

2150

Contact
Form

SINGLE-IN-LINE (SIL)
Reed relay products are available in standard single-in-line packages for mounting
on a printed circuit board or socket.
Overall Dimensions
Product
Series

Description

Reed Relay, SIL, SPST-NO

mm (inch)

Vdc

Vdc

Ohms

Vdc

A

W

LxWxH

LxWxH

Nominal

Max.

Nominal

Max.

Max.

Max.

5

22

500

12

22

500

200

0.5

10

Form A

24

44

2000
125
175

0.25

5

Form C

300

0.5

10

Form A

24.13 (0.950) x 7.00 (0.276) x 7.40 (0.291)

24.90 (0.980) x 7.60 (0.299) x 7.80 (0.307)

HE3321C0500
Reed Relay, SIL, SPDT-CO

24.13 (0.950) x 7.00 (0.276) x 7.40 (0.291)

24.90 (0.980) x 7.60 (0.299) x 7.80 (0.307)

HE3321C2400
HE3351A0500
HE3351A1200
HE3351A2400

Reed Relay, SIL, SPST-NO,
High Voltage

Contact Ratings, Switching

mm (inch)

HE3321A2400
HE3321C1200

Coil
Resistance

External Shield Body

HE3321A0400
HE3321A1200

Coil Voltage

Transfer Molded Body

24.13 (0.950) x 7.00 (0.276) x 7.40 (0.291)

24.90 (0.980) x 7.60 (0.299) x 7.80 (0.307)

5

11

12

22

500

24

44

2000
125

5

14

12

22

500

24

44

2000

Contact
Form

MINIATURE SINGLE-IN-LINE (SIL)
Reed relay products are available in smaller profile single-in-line packages
for mounting on a printed circuit board or socket.
Overall Dimensions
Product
Series

Description

Reed Relay, SIL, SPST-NO

HE3671A1200
HE3671A2400

10

Reed Relay, SIL, SPST-NO,
Data Switching

Contact Ratings, Switching

mm (inch)

mm (inch)

Vdc

Vdc

Ohms

Vdc

A

W

LxWxH

LxWxH

Nominal

Max.

Nominal

Max.

Max.

Max.

5

14

500

12

22

1000

200

0.5

10

Form A

24

31

2150
200

0.5

10

Form A

19.05 (0.750) x 5.08 (0.200) x 7.45 (0.293)

19.70 (0.776) x 5.65 (0.222) x 7.87 (0.310)

HE3621A2400
HE3671A0500

Coil
Resistance

External Shield Body

HE3621A0500
HE3621A1200

Coil Voltage

Transfer Molded Body

19.05 (0.750) x 5.08 (0.200) x 7.45 (0.293)

19.70 (0.776) x 5.65 (0.222) x 7.87 (0.310)

Littelfuse electronics product portfolio includes Hamlin

5

14

500

12

22

1000

24

31

2150

Contact
Form

Magnetic Actuators
RECTANGULAR
These rectangular bare magnets and packaged actuators are ideally suited for mounting
on a flat surface. They are suitable for use in a wide range of environments, including
high-temperature applications.
Overall Dimensions

Recommended Operating Temp.

Product
Series

Description

H-31

AlNiCo Magnet

12.70 (0.500) x 1.60 (0.062) x 1.60 (0.062)

AlNiCo-5

300

H-32

AlNiCo Magnet

25.40 (1.000) x 4.80 (0.190) x 4.80 (0.190)

AlNiCo-5

300

H-33

AlNiCo Magnet

19.10 (0.750) x 3.20 (0.120) x 3.20 (0.120)

AlNiCo-5

300

H-34

AlNiCo Magnet

25.40 (1.000) x 6.35 (0.250) x 6.35 (0.250)

AlNiCo-5

300

H-40

Neodymium Magnet

7.62 (0.300) x 3.18 (0.125) x 3.18 (0.125)

NdFeB 45H

120

H-41

Neodymium Magnet

19.05 (0.750) x 3.18 (0.125) x 3.18 (0.125)

NdFeB 35H

120

H-58

Neodymium Magnet

21.00 (0.827) x 7.00 (0.276) x 4.70 (0.185)

NdFeB 35H

120

57105

Actuator for Terminal Flange Mount Sensor

40.17 (1.582) x 19.05 (0.750) x 6.35 (0.250)

AlNiCo-5

105

57125

Actuator for Pinned Flange Mount Sensor

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

AlNiCo-5

300

57135

Actuator for High-Temp Flange Mount Sensor

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

AlNiCo-5

150

57140

Actuator for Mini Flange Mount Sensor

23.00 (0.906) x 14.00 (0.551) x 6.00 (0.236)

AlNiCo-5

105

57141

Actuator for Mini Flange Mount Sensor

23.00 (0.906) x 14.00 (0.551) x 6.00 (0.236)

NdFeB 35H

105

57145

Actuator for Flange Mount Sensor

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

AlNiCo-5

105

57150

Actuator for Flange Mount Sensor

28.57 (1.125) x 19.05 (0.750) x 6.35 (0.250)

AlNiCo-5

105

57045

Actuator for Mini PCB Mount Overmolded

17.78 (0.700) x 3.30 (0.130) x 4.32 (0.170)

AlNiCo-5

105

57050

Actuator for PCB Mount Overmolded

22.86 (0.900) x 4.57 (0.180) x 4.57 (0.180)

AlNiCo-5

105

mm (inch)

Material

˚C

LxWxH

Max.

CYLINDRICAL
Designed for mounting on a frame, these cylindrical bare magnets and packaged actuators are
appropriate for use in a wide range of environments, including high-temperature applications.
Overall Dimensions

Recommended Operating Temp.

Product
Series

Description

H-35

Neodymium Magnet

6.35 (0.250) x 6.35 (0.250)

NdFeB 35H

120

H-48

Neodymium Magnet

4.40 (0.173) x 6.00 (0.236)

NdFeB 35SH

120

CM-1

Ceramic Magnet

12.70 (0.500) x 5.08 (0.200)

Ceramic-5

125

H-36

AlNiCo Magnet

4.60 (0.182) x 25.40 (1.000)

AlNiCo-5

300

H-315

AlNiCo Magnet

3.00 (0.118) x 15.00 (0.590)

AlNiCo-5

300

H-420

AlNiCo Magnet

4.00 (0.157) x 20.0 (0.787)

AlNiCo-5

300

H-625

AlNiCo Magnet

6.00 (0.236) x 25.0 (0.984)

AlNiCo-5

300

57020

Actuator for Mini Firecracker

5.10 (0.201) x 15.24 (0.600)

AlNiCo-5

105

57022

Actuator for Firecracker

5.80 (0.228) x 25.40 (1.000)

AlNiCo-5

105

57025

Actuator for Firecracker

6.22 (0.245) x 25.40 (1.000)

AlNiCo-5

105

57030

Actuator for Long Firecracker

6.22 (0.245) x 38.10 (1.500)

AlNiCo-5

105

mm (inch)

Material

ØxL

˚C
Max.

57060

Actuator for Stainless Threaded Barrel Sensor

M8 x 1.25 Pitch x 36.00 (1.420)

AlNiCo-5

105

57065

Actuator for Threaded Barrel Sensor (Standard)

(5/16 x 24) Pitch x 38.10 (1.500)

AlNiCo-5

105

57070

Actuator for Threaded Barrel Sensor (Metric)

M8 x 1.25 Pitch x 38.10 (1.500)

AlNiCo-5

105

57075

Actuator for Heavy Duty Threaded Barrel

M12 x 1.00 Pitch x 46.00 (1.810)

Ceramic-2

125

hamlin.com | littelfuse.com

11

Applications
Proximity Sensing Using Reed Sensors—
Refrigerator Door
Features and Benefits:

Appliances like refrigerators, freezers and wine coolers are used to keep food/
beverages cold and extend their useful life. These appliances contain lights to
illuminate the inside compartments when the doors are open. However, the
lights only need to turn on when a door is open. To accomplish this, a proximity
sensor is needed to detect if the appliance door is open or closed.

• No physical contact required
to operate the switch

A reed sensor can be used to detect the position of the door. In refrigerators, a
reed sensor is mounted to the frame of the appliance and a permanent magnet
is mounted to each door. Each reed sensor and magnet pair is positioned so
that the reed switch contacts close only when the door is completely closed.
The position of the reed sensor’s contacts can be monitored by an electronic
control unit (ECU) within the refrigerator’s electronics assembly to turn
the interior lights on and off as needed.

• Electrical contacts are within
a hermetically sealed capsule
that is immune to moisture,
dust and dirt

Reed sensors are ideal for a variety of position- and proximity-sensing
applications where there is a need to detect the presence of a moving part
in relation to a sensor in a fixed location.
LED Light

S

User Interface

• Overmolded sensors provide
additional protection against
mechanical stresses and
vibration
• Low-cost alternative
to mechanical switch

Suggested Products:
• FLEX-14 (14 mm reed switch)

• 59025 (Firecracker reed sensor)

• MDCG-4 (15 mm reed switch)

• 59140 (Flange mount
reed sensor)

• MDSR-10 (10 mm reed switch)

Similar Applications:

Reed Sensor

N

Magnet

• Zero power required for switch
actuation

• Wide operating temperature
range adequate for use in cold
temperatures

Frost Sensing

Electronic Control Unit

Refrigerators/freezers, dish washers, washing machines, rice cookers,
coffee makers, vacuum cleaners and vending machines

Temp Sensing

Ice Dispenser

Figure 1-Reed sensors detect the opening of refrigerator doors

Proximity Sensing Using Hall Effect Sensors—
Garage Door
Hall effect sensors can be used to detect the movement of a garage door to
stop the motor once the door has reached its open or closed position. Typically,
a system of two Hall effect sensors, each associated with its own permanent
magnet, is used to determine whether the door is completely open, completely
closed or somewhere in between.
One of the magnets is mounted on the chain drive of the garage door opener so
that it is positioned directly next to the Hall effect sensor used to detect a closed
door. The other magnet is positioned so that it moves with the chain and is located
directly next to the other Hall effect sensor when the door is completely open.
Similar to reed sensors, Hall effect sensors are ideal for position or proximity sensing
where there is a need to detect the presence of a moving part in relation to one or
more sensors in fixed locations. They offer extended life and reliability over reed
sensors since there are no electrical contacts that are opened and closed. Common
examples include door- and lid-position sensing in the similar applications listed.

Hall Effect
Sensor

Features and Benefits:
• No physical contact required
to operate the switch
• Wide operating temperature range
adequate for use in hot and cold
temperatures
• Hall effect sensor is an integrated
circuit with no mechanical moving
components

• Encapsulated sensors provide
additional protection against
environmental/mechanical stresses
and vibration
• Reliable operation for millions
of cycles
• Low-cost alternative to mechanical
switches or infrared/optical sensors

Suggested Products:
• 55100 (Miniature flange mount
Hall effect sensor)

• 55310 (Flat pack digital Hall
effect sensor)

• 55140 (Flange mount Hall
effect sensor)

Receiver
N
S

Similar Applications:
Electronic Control Board

Motor Drive

S
N

Power Supply

Figure 2-Garage door, Hall effect sensors mounted above garage door opener

12

Littelfuse electronics product portfolio includes Hamlin

Dishwashers, washing machines, vacuum cleaners, security locks
on doors and vending machines

Speed Sensing Using Reed Sensors—
Treadmill Pulley
Reed switch-based sensors are used as highly effective speed sensors in low-cyclerate applications with rates up to a few thousand revolutions per minute (RPM).
For example, in treadmills, a reed sensor is used to detect the speed of the moving
belt. Two permanent magnets are placed on diametrically opposite ends of the belt
pulley, and a reed sensor is mounted to the treadmill frame perpendicular to one
end of the pulley. As the treadmill pulley rotates, the reed sensor detects when
each of the magnets is close to the sensor. The time interval between the detection
of each magnet is used to compute the speed at which the pulley is rotating.
Reed sensors are highly accurate in speed-sensing applications where there
is a rotating part. They are commonly used in fitness equipment where there
is a rotating part with a variable speed.

Display Board

Features and Benefits:
• Effective, noncontact solution
used to switch the sensor

• Low-cost alternative to infrared/
optical sensors

• Digital output signal is used to
compute speed with high accuracy

• Overmolded sensors provide
additional protection against
mechanical stresses and vibration

• Long lifetime and reliable sensing
for millions of operations

Suggested Products:
• 59025 (Firecracker)

• 59140 (Miniature flange mount)

• 59065 (Threaded barrel)

• 59150 (Flange mount)

User Interface

Similar Applications:
Main Motor Board

Reed Sensor

Motor Drive

Fitness equipment, including treadmill, stationary bicycle and elliptical
cross-trainer

Power Supply

Figure 3-Treadmill pulley

Speed Sensing Using Hall Effect Sensors—
Washing Machine Drum Speed
Hall effect sensors make very effective rotary speed sensors. The strengths of
these sensors are their reliability, repeatability, accuracy and high speed. For
example, in a clothes washing machine, a digital or latching Hall effect sensor
can be used to detect a rotating ring magnet to determine the rotating speed
of the drum. Multipole magnets (e.g., 8–40 poles) are typically used as the ring
magnets in these designs. The frequency and resolution of speed are affected
by the number of magnet poles.
Direction, as well as speed, can be measured. The direction signal can be
provided by either quadrature signaling or with the direction encoded in the
pulse width. Quadrature signaling involves two square wave speed signals
where the direction of rotation is determined by the lead vs. lag phase
relationship between the two signals.
Another popular method of detecting speed is to use Hall effect speed sensors
to detect rotating ferrous gear teeth such as in an automotive transmission
speed sensor application. The Hall effect sensor has a back-bias magnet
and detects the variation in magnetic flux density between the gear
tooth and the Hall effect sensor.

Display Board

Flux Concentration-Tooth Position
Single Low

S

Flux Concentration-Valley Position
Single High

S

N

N

Figure 5-Geartooth sensing

Features and Benefits:
• Digital output signal is used to
compute speed with high accuracy

• Effective for high-speed
applications

• Long lifetime and reliable sensing
for millions of operations

User Interface

Suggested Products:
Hall Effect Sensor
Main Motor Board

Main Motor

• 55140 (Flange mount)

• 55075 (Geartooth sensor)

• 55310 (Flat pack digital)

• Custom-designed sensor

• 55505 (Geartooth sensor)

Power Supply

Figure 4-Washing machine drum speed sensor with ring magnet

Similar Applications:
DC motors, vacuum cleaners and wheel speed

hamlin.com | littelfuse.com

13

Applications (continued)

Security and Alarm Systems—
Door and Window Alarms
Many types of security alarm systems use a reed switch/sensor attached to the frame
of the door or window. The actuating magnet is attached to the moving door or
window so that when it is opened, the reed sensor detects the moving magnet
and opens/closes its electrical contacts—sending a signal to the alarm system.

Features and Benefits:

Similarly, reed switches can easily be mounted to circuit boards used in smoke
or gas alarm systems. In portable systems, such as gas detectors, the reed switch
is used to activate the system when the handheld detector or reader is placed
in the docking station. In systems with smoke/gas detectors in fixed positions,
the reed switch can be activated with a handheld magnetic wand to put the
detector in test mode.

• Zero power required for
switch actuation

Reed switches and reed sensors are effective solutions for many types of
security and alarm sensor applications. Examples include detecting the door
and window position, measuring the sump pump water level or activating the
test mode of a smoke detector. Reed relays can be used to activate the alarm
loop in active sensors like motion sensors and smoke detectors.

• No physical contact is required
to operate the switch

• Wide operating temperature range
adequate for use in hot and cold
temperatures

S
N

Alarm Driver

Reed
Sensor

• Overmolded sensors provide
additional protection against
mechanical stresses
• Low-cost alternative to mechanical
switches

Suggested Products:
• MDSM-10 (10 mm reed switch)
• 59020 (Miniature firecracker)
• 59140 (Miniature flange mount)

Magnet

• Electrical contacts are within a
hermetically sealed capsule that is
immune to moisture, dust and dirt

• 59170 (11 mm overmolded
reed switch)
• HE3621A0510 (Miniature SIL
reed relay)

Similar Applications:
Burglar systems, smoke alarms and gas detection systems

Electronic Control Unit

Power Circuit

Figure 6-Door alarm system using a reed sensor

Continuous Level Sensing—
Industrial Tank Water Level
Resistive reed ladder networks are used to measure the liquid level in a tank,
which allows for a continuous output signal rather than discrete signals from
single-point level sensors. This continuous level sensor produces a variable
resistance or continuous current/voltage that is related to the position of the
float/magnet assembly. As the liquid level changes, the relative float position
follows, activating the reeds sequentially and producing the associated output
voltage or resistance value. The typical spacing between reed switches is
usually provided in 6.35 mm or 12.7 mm steps.
Littelfuse supplies full assemblies that include stainless steel or plastic
housings. Bare reed switches are also available.
Level sensors incorporating reed switch and resistance technology are
commonly used for measuring continuous liquid levels in the automotive,
marine and industrial markets. The float, which contains a magnet, moves
up or down over the sealed stem containing the reed switches/resistors.

Features and Benefits:
• Continuous level output signal,
not like a single-point level sensor
• Electrical contacts are within a
hermetically sealed capsule that is
immune to moisture, dust and dirt

• Wide operating temperature range
adequate for use in hot and cold
temperatures

• Sensor housing provides protection
against mechanical stresses
and vibration

Suggested Products:
• MDSM-10 (10 mm reed switch)
• MDSM-4 (15 mm reed switch)

+ DC24V

• Reliable switching for millions
of open/close operations

• Custom-designed level sensor
assemblies

Similar Applications:

Load
R5
R2

Fluid-level sensing for: urea in diesel trucks, fuel tanks, HVAC refrigerator
tanks and condensate water tanks

R1

R4

R3

Converter
Sensor

N

N

S

S

Float
with
Magnet

Empty
White
(Level Signal)

Black
(Ground)

S1

S0

R0

S2

R3

S4

S3

R2

R3

S11

R4

R11

S12

R12

S13

S14

R13

R14

S15

R15

Full
S16

R16

Blue
(Thermistor Single)

Figure 7-Resistive reed ladder network for level sensing

14

Littelfuse electronics product portfolio includes Hamlin

Level Sensing—
Dishwasher Water Level
When provided with a float magnet, reed sensors can function as fluid-level
sensors. For example, in a dishwasher, a float-type level sensor is used to detect
if the water level inside of the water collection pan has reached the fill limit. The
float sensor consists of a reed switch mounted within a shaft and a permanent
magnet provided within a float housing. The shaft is vertically mounted within
the water collection pan so that the reed switch is positioned at the water fill
limit of the pan. As the water level rises, the magnet within the float travels up
the shaft to the point where it comes into the proximity of the reed switch. The
reed switch senses the presence of the magnet and signals the dishwasher’s
ECU that the water level has reached its fill limit.
Level sensors incorporating reed switch technology are low-cost solutions
for any application where there is a need to detect the amount of liquid in
a tank or pan. They are commonly used in white goods and appliances.

User Interface

Reed Sensor

• Zero power required for switch
actuation
• Electrical contacts are within a
hermetically sealed capsule that is
immune to moisture, dust and dirt

adequate for use in hot and cold
temperatures
• Sensor housing provides protection
against mechanical stresses
and vibration
• Reliable switching for millions
of open/close operations

• Wide operating temperature range

Suggested Products:
• 59630 (Float sensor)

• MACD-14 (14 mm reed switch)

• FLEX-14 (14 mm reed switch)

• 59300 (Level sensor)

Similar Applications:

ECU

Dish washers, washing machines, air conditioners, dehumidifiers and
coffee brewers

S
N

Pump Control

• No physical contact required
to operate the switch

• MDSR-10 (10 mm reed switch)

Floating Magnet

Cold Water Valve

Features and Benefits:

Hot Water Valve

Temp Sensor

Figure 8-Float sensor detecting water level in a dishwasher

Flow Switch—
Tankless Water Heater
A flow switch utilizes a reed switch to detect the motion of a valve, paddle
wheel or piston that is fitted with a permanent magnet. For example, in some
tankless water heater units, the flow sensor contains a permanent magnet that
is fixed to a piston that moves when there is water pressure present in the
system. As the water pressure increases, the piston movement brings
the magnet into the proximity of the reed switch. This causes the reed switch
to close and signals the presence of water flow.
A flow sensor utilizes a turbine with an attached magnet that rotates by a fixed
reed switch or Hall effect sensor. The speed at which the turbine rotates is
proportional to the flow rate of the fluid.
Reed sensors are highly effective solutions for flow-sensing applications
where there is a need to detect the presence of liquid or gas flow in a system.
Common uses include water or gas flow in the similar applications listed.

User Interface

N

S

• Zero power required for switch
actuation
• Wide operating temperature range
adequate for use in hot and cold
temperatures

• Electrical contacts are within a
hermetically sealed capsule that is
immune to moisture, dust and dirt
• Overmolded sensors provide
additional protection against
mechanical stresses
• Reliable switching for millions
of open/close operations

Suggested Products:
• MDSM-4 (15 mm reed switch)

• MDSR-10 (10 mm reed switch)

• MLSM-4 (15 mm reed switch)

• 59165 (16 mm overmolded reed switch)

• MDCG-4 (15 mm reed switch)

• 59170 (11 mm overmolded reed switch)

Similar Applications:
Water Flow

S

• No physical contact is required
to operate the switch

Ignition Circuit

Outlet

N

Features and Benefits:

Inlet

ECU

Dish washers, washing machines, hot tubs and utility gas meters

Reed Sensor
Power Circuit

Figure 9-Flow detection in a tankless water heater

hamlin.com | littelfuse.com

15

Beyond Sensing...
Littelfuse offers circuit protection…
Littelfuse circuit protection products can be used with Hamlin reed switch and sensor products to enhance safety and reliability in various
load-switching applications. We recommend using circuit protection for the following examples of load switching:
Inductive Load Switching – Arc suppression is recommended to maximize the operating life of inductive loads. For DC loads, a diode should
be used. For AC loads, a transient voltage suppression (TVS) diode, a metal oxide varistor (MOV) or a resistor-capacitor (RC) suppression
device may be used. MOV and RC suppression devices should not have too much capacitive inrush current as described below.
Capacitive Load Switching – Capacitance in the load circuit or long cables may cause permanent or intermittent contact sticking.
Contact protection is recommended if the energy stored in the capacitor (E = ½CV2) is greater than 1 µJ. Use a small value resistor
in series with the reed switch for contact protection.

A BROAD & DEEP PORTFOLIO
Littelfuse offers the world’s broadest and deepest portfolio of circuit protection
solutions. Our extensive knowledge and experience in circuit protection
technologies are accessible to our customers around the globe. If you have a
unique circuit protection problem, we have the expertise and resources needed
to develop a solution that delivers exceptional safety and reliability. Our global
research and development teams are constantly working on innovative circuit
protection technologies designed to safeguard the latest products on the market.

Fuse Blocks

Over-Current Protection
• Fuses
• Resettable positive temperature coefficient (PTC) devices

Fuse Clips

Over-Voltage Suppression
• Gas discharge tubes (GDTs)		

• TVS diode arrays

• PLED Series open LED protectors

• SIDACtor® devices

• PulseGuard ESD Suppressors 		

• Switching thyristors

®

• TVS diodes			 • Varistors

Fuse Holders

Varistors

Fuses
SIDACtor®
Devices

TVS
Diode Arrays
PLED
LED Protectors

Switching
Thyristors

16

LF-Hamline-V23.indd 18

1/28/15 1:49 PM

Global Footprint…
At Littelfuse, our mission is to develop innovative circuit protection, power
control and sensing solutions that meet our customers’ unique needs.
This customer-focused philosophy has helped us become the top circuit
protection brand in the world.
Our industry-leading product portfolio includes reliable circuit protection, power
control and sensing products that are designed for a variety of applications. We have
assembled unparalleled expertise and developed a global footprint that puts our
facilities close to our customers and target markets. As our global manufacturing
and R&D teams objectively recommend the best circuit protection, power control or
sensing solution for each customer application, they form partnerships that will lead
to the development of the next generation of advanced products.

Gas Discharge
Tubes

PulseGuard®
ESD Suppressors

TVS Diodes

Resettable
PTC Devices
©2015 Littelfuse, Inc. Specifications, descriptions and illustrative material in this
literature are as accurate as known at the time of publication, but are subject to
change without notice. Visit www.littelfuse.com for more information.

LF-Hamline-V23.indd 19

1/28/15 1:49 PM

Littelfuse electronics product portfolio includes:

littelfuse.com
hamlin.com

EC133Nv0115



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