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permanent magnets

Magnetic Reed Switches

A Reed Switch requires either a permanent magnet or magnetic field in order to activate the switch, thus it is commonly called a Magnetic Reed Switch.  Permanent magnets are available in a variety of different sizes, magnetic materials, and shapes such as cylindrical, rectangular, disk or ring form. 

The interaction between the Reed Sensor/Switch and Magnet is influenced by the magnet's mounting position, environment and the presence of another magnetic field.

Ideally, the magnet should be mounted in the moving part of the application. Professional tuning of the magnet and Reed Switch can improve the overall functionality of the whole sensor-magnet system.

Download Activation Distance Chart for 13 Sensor Product Series

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Stock Check

Item no. Distributor Region Quantity Cart RFQ Inventory Date
4003003040Relay Specialties, IncUSA14RFQ7/27/2014 6:06:00 AM
4003003040TTI Inc Global HeadquartersUSA500RFQ7/27/2014 12:14:00 AM
4003004003DIGI-KEYUSA825RFQ7/29/2014 12:23:00 AM
4003004006DIGI-KEYUSA2878RFQ7/29/2014 12:23:00 AM
4003004006TTI Inc Global HeadquartersUSA750RFQ7/27/2014 12:14:00 AM
4003004015DIGI-KEYUSA679RFQ7/29/2014 12:23:00 AM
4003004017DIGI-KEYUSA1074RFQ7/29/2014 12:23:00 AM
4003004018DIGI-KEYUSA163RFQ7/29/2014 12:23:00 AM
4003004025ONLINECOMPONENTS.COMUSA1968RFQ7/29/2014 1:58:00 AM
4003004025DIGI-KEYUSA4531RFQ7/29/2014 12:23:00 AM
4003004025Master ElectronicsUSA1968RFQ7/29/2014 12:03:00 AM
4003004026ONLINECOMPONENTS.COMUSA217RFQ7/29/2014 1:58:00 AM
4003004026DIGI-KEYUSA653RFQ7/29/2014 12:23:00 AM
4003004026Master ElectronicsUSA217RFQ7/29/2014 12:03:00 AM
4003004030ONLINECOMPONENTS.COMUSA100RFQ7/29/2014 1:58:00 AM
4003004030DIGI-KEYUSA228RFQ7/29/2014 12:23:00 AM
4003004030Master ElectronicsUSA90RFQ7/29/2014 12:03:00 AM
4003004032DIGI-KEYUSA791RFQ7/29/2014 12:23:00 AM
NDFEB 10X5X1.9MMPUI Projections Unlimited, Inc.USA100RFQ7/29/2014 1:19:00 AM
NDFEB 10X5X1.9MMDIGI-KEYUSA791RFQ7/29/2014 12:40:00 AM
NDFEB 10X5X1.9MMMouser ElectronicsUSA284RFQ7/26/2014 2:07:00 AM
NDFEB 10X5X1.9MMFarnell element14UK2791RFQ7/28/2014 3:08:00 AM
NDFEB 10X5X1.9MMelement14Singapore1697RFQ7/28/2014 1:20:00 AM
NDFEB 6X10MMDIGI-KEYUSA228RFQ7/29/2014 12:40:00 AM
NDFEB 6X10MMMouser ElectronicsUSA205RFQ7/26/2014 2:07:00 AM
NDFEB 8X15MMFarnell element14UK272RFQ7/28/2014 3:08:00 AM
NDFEB 8X15MMelement14Singapore269RFQ7/28/2014 1:20:00 AM
NDFEB6X10MMONLINECOMPONENTS.COMUSA100RFQ7/29/2014 2:08:00 AM
NDFEB6X10MMMaster ElectronicsUSA100RFQ7/29/2014 12:12:00 AM
ALNICO500 19X3.2X3.2Mouser ElectronicsUSA635RFQ7/26/2014 2:07:00 AM
ALNICO500 19X3.2X3.2MMDIGI-KEYUSA163RFQ7/29/2014 12:26:00 AM
ALNICO500 2.5X12.7MMDIGI-KEYUSA212RFQ7/29/2014 12:26:00 AM
ALNICO500 2.5X12.7MMMouser ElectronicsUSA141RFQ7/26/2014 2:07:00 AM
ALNICO500 3X12MMFarnell element14UK876RFQ7/28/2014 3:08:00 AM
ALNICO500 3X12MMelement14Singapore458RFQ7/28/2014 1:20:00 AM
ALNICO500 4X19MMDIGI-KEYUSA825RFQ7/29/2014 12:26:00 AM
ALNICO500 4X19MMMouser ElectronicsUSA175RFQ7/26/2014 2:07:00 AM
ALNICO500 4X19MMFarnell element14UK1396RFQ7/28/2014 3:08:00 AM
ALNICO500 4X19MMelement14Singapore1370RFQ7/28/2014 1:20:00 AM
ALNICO500 5X22MMFarnell element14UK142RFQ7/28/2014 3:08:00 AM
ALNICO500 5X22MMelement14Singapore68RFQ7/28/2014 1:20:00 AM
ALNICO500 7.5X27MMDIGI-KEYUSA2878RFQ7/29/2014 12:26:00 AM
ALNICO500 7.5X27MMMouser ElectronicsUSA54RFQ7/26/2014 2:07:00 AM
ALNICO500 7.5X27MMFarnell element14UK282RFQ7/28/2014 3:08:00 AM
ALNICO500 7.5X27MMelement14Singapore256RFQ7/28/2014 1:20:00 AM
SMCO5 1.9X3MMDIGI-KEYUSA1074RFQ7/29/2014 12:43:00 AM
SMCO5 1.9X3MMMouser ElectronicsUSA256RFQ7/26/2014 2:07:00 AM
SMCO5 3X4MMDIGI-KEYUSA4531RFQ7/29/2014 12:43:00 AM
SMCO5 3X4MMMouser ElectronicsUSA164RFQ7/26/2014 2:07:00 AM
SMCO5 3X4MMFarnell element14UK2189RFQ7/28/2014 3:08:00 AM
SMCO5 3X4MMelement14Singapore1517RFQ7/28/2014 1:20:00 AM
SMCO5 5X4MMDIGI-KEYUSA653RFQ7/29/2014 12:43:00 AM
SMCO5 5X4MMMouser ElectronicsUSA201RFQ7/26/2014 2:07:00 AM
SMCO5 5X4MMFarnell element14UK1000RFQ7/28/2014 3:08:00 AM
SMCO5 5X4MMelement14Singapore606RFQ7/28/2014 1:20:00 AM
SMCO53X4MMONLINECOMPONENTS.COMUSA1968RFQ7/29/2014 2:11:00 AM
SMCO53X4MMMaster ElectronicsUSA1771RFQ7/29/2014 12:14:00 AM
SMCO55X4MMONLINECOMPONENTS.COMUSA217RFQ7/29/2014 2:11:00 AM
SMCO55X4MMMaster ElectronicsUSA195RFQ7/29/2014 12:14:00 AM


Magnetics


Reed Switch & Magnet Actuation
Click to AnimateActuator Type
PositionMovementActuation(s)Contact Form / Mode
Magnet Actuation 1

Bar Magnet

Parallel

Perpendicular

Single

Form A (Normally Open)


Magnet Actuation 2

Bar Magnet

Parallel

Parallel

Single

Form A (Normally Open)

Magnet Actuation 3

Bar Magnet

Parallel

Parallel

Multiple

Form A (Normally Open)

Magnet Actuation 4

Bar Magnet

Parallel

Parallel

Single

Form A (Normally Open)

Magnet Actuation 5

Bar Magnet

Adjacent

Rotary

Multiple

Form A (Normally Open)

Magnet Actuation 6

Ring Magnet

Adjacent

Rotary

Multiple

Form A (Normally Open)

Magnet Actuation 7

Ring Magnet

Adjacent

Rotary

Multiple

Form A (Normally Open)

Magnet Actuation 8

Bar Magnet

Above

Rotary

Multiple

Form A (Normally Open)

Magnet Actuation 9

Bar Magnet

Perpendicular

Perpendicular

Single

Form A (Normally Open)

Magnet Actuation 10

Bar Magnet

Perpendicular

Parallel

Multiple

Form A (Normally Open)

Magnet Actuation 11

Bar Magnet

Parallel

Parallel

Single

Form A (Normally Open)

Magnet Actuation 12

Bar Magnet

Parallel

Perpendicular

Single

Form B (Normally Closed)

Magnet Actuation 13

Bar Magnet

Parallel

Pivot

Single

Form A (Normally Open)

Magnet Actuation 14

Bar Magnet

Magnetic Shield

Fixed

Parallel

Single

Form A (Normally Open)

Magnet Actuation 15

Bar Magnet

Magnetic Shield

Fixed

Perpendicular

Single

Form A (Normally Open)

Magnet Actuation 16

Bar Magnet

Magnetic Shield

Fixed

Parallel

Single

Form A (Normally Open)

Associated Parts

Reed Sensors

Pair any of these reed sensor(s) with the above corresponding magnet for a complete sensor system solution.  Other package styles may also be used, please consult the factory for more options.


Rectangular Screw Mount Sensors

MK02 Reed Sensor MK04 Reed Sensor MK05 Reed Sensor MK09 Reed Sensor MK12 Reed Sensor MK13 Reed Sensor MK21 Reed Sensor MK26 Reed Sensor MK27 Reed Sensor

Cylindrical & Threaded Panel Mount Sensors

MK03 Reed Sensor MK07 Reed Sensor MK11 Plastic Reed Sensor MK11 Stainless Reed Sensor MK11 Brass Reed Sensor MK14 Reed Sensor MK18 Reed Sensor MK20 Reed Sensor MK20/1 Reed Sensor

       

PCB Through Hole Sensors

M02/6 & MK02/7 Reed Sensors MK06 Reed Sensors

FAQ

Magnets & Magnetics

Why would magnetic mapping be done?

Why would magnetic mapping be done?

In reed sensor applications it is important to understand the exact pull-in and drop-out fields.  This information then allows one to properly position the magnet and sensor well within appropriate guard bands and avoid any tolerance issues.  Most users have no idea what the actual magnetic field looks like. Presenting the fields in a three dimensional view gives the user a better chance to have an optimized design.  This will help define adequate operate and deactivate points. Additionally, this will insure operation takes place well within the magnetic envelopes to avoid tolerance issues.  We can insure acceptable hysteresis between the operate and deactivate points.  We can optmize the sensor and magnet costs.

What is magnetically mapping?

What is magnetically mapping?

Magnetic mapping is the method of incrementally measuring the pull-in and drop-out points by either holding the sensor stationary while moving the magnet or vice versa.  The movement must be carried out in all three dimensions.  Software is then used to bridge all the points allowing the magnetic field to be visualized in three dimensions.

What is annealing?

What is annealing?

When metal is subjected to a very high temperature bath, that process is called annealing.  The temperature is slowly increased to a max temperature where it is stabilized for a period of time, and then the temperature is slowly reduced back to room temperature.  This process will leave the metal in its softest state.  For a reed switch this is very important because this point is also where the nickel/iron leads have near zero magnetic retentivity.  This means when the reed switch contacts are subjected to a magnetic field and then the magnetic field is removed, there will be no residual magnetism on the leads.

Is there any net effect if a reed switch is subjected to an extremely high magnetic field?

Is there any net effect if a reed switch is subjected to an extremely high magnetic field?

No.  There is no net effect on the reed switch, once the magnetic field saturates the reed switch contacts it no longer has any effect.

What is an electromagnet?

What is an electromagnet?

An electromagnet is a magnetic field generated when a coil of wire is formed in a cylindrical shape.  The magnetic field will be uniform through the entire length of its inner opening.

What does ferromagnetic mean?

What does ferromagnetic mean?

Ferromagnetic is the property of a material that allows it to become magnetized permanently or temporarily when in the influence of a magnetic field generated by a permanent magnet or an electromagnet. 

Will the magnetic properties of a magnet change if the magnet is dropped on a hard surface?

Will the magnetic properties of a magnet change if the magnet is dropped on a hard surface?

No nothing will happen.  There were rumors abound which indicated that the magnetic strength would be affected, but this is just not true.

Can a magnet packaged with a reed switch be turned into a temperature sensor?

Can a magnet packaged with a reed switch be turned into a temperature sensor?

A magnet and reed switch can be turned into a temperature sensor by using a magnet that has a certain curie temperature for the temperature you want to sense.  When that curie temperature is reached the magnet loses its magnetic properties whereby the reed switch contacts open.  When the temperature drops below the curie temperature, the reed contacts will close.

Why use different types of magnets?

Why use different types of magnets?

Using different magnets allows you to select the characteristic which best fits the application:

  • Ferrites are low cost
  • Alnicos are the most stable over a wide temperature range
  • Rare earth offer the strongest magnetic fields

How do you make a uniform magnetic field and why would you?

How do you make a uniform magnetic field and why would you?

A uniform magnetic field can be made by making a relatively long cylindrical coil. Once current is flowing through the coil a uniform magnetic field will exist all along the inside of the coil. This is not true at the very ends of the coil.  Helmholtz coils can be bought for the very reason of supplying a uniform magnetic field.  In either case, the uniform magnetic fields allow for calibration.

Is there such a thing as an ideal size magnet?

Is there such a thing as an ideal size magnet?

Yes there is and it clearly depends on the type of magnet.  The length to diameter is the key ratio.

  • Alnico 5 is 5:1
  • Alnico 8 is 3:1
  • Ferrites are 1:1 
  • Rare earth is 1:1

Why use a Helmholtz coil?

Why use a Helmholtz coil?

Using a Helmholtz coil makes it very easy to calibrate magnetic fields in either ampere turns (AT) or milliTesla (mT).

What is a Helmholtz coil?

What is a Helmholtz coil?

A Helmholtz coil is actually two concentric coils mounted parallel to each other and when energized by passing a current through them they will produce a uniform magnetic field between the two coils.

What is the Curie effect?

What is the Curie effect?

The Curie effect is when a magnet reaches a certain temperature, its magnetic properties will be eliminated.  Once the temperature drops below the Curie temperature the magnetic effects of the material will return.

How is a magnetic field produced?

How is a magnetic field produced?

Generally winding fine copper wire in a cylindrical configuration will create a magnetic field internal to the cylinder, when a current is passed through the copper wire.

How is an artificial magnet made?

How is an artificial magnet made?

Artificial magnets can be created by doping iron, nickel, and/or cobalt with other elements.  Doping with rare earth materials has been particularly successful, producing very strong magnets.

Where does magnetic energy come from?

Where does magnetic energy come from?

The magnetic force is generated at the subatomic level and the energy comes from heat.  Any temperature above absolute 0 (-273°C)

What is a dipole?

What is a dipole?

A dipole is the basic building block of a magnetic field.  A dipole is the magnetic effect from a single atom.  When taken many million times over, one has a magnetic field being generated from a magnet.

What are the different types of magnets?

What are the different types of magnets?

There are mainly three different types of permanent magnets:

  1. Alnico -most stable and best temperature effects
  2. Rare earth -strongest magnets
  3. Ferrite -lowest cost

What is a magnet?

What is a magnet?

A magnet is composed of ferromagnetic material which means it must contain at least one of the following: nickel, iron or cobalt. It must also be able to sustain magnetism.

What is magnetic and where does it come from?

What is magnetic and where does it come from?

Magnetic is a force produced at the subatomic level.  It is caused by electrons spinning and also rotating around the nucleus of the atom.

Go to FAQs about Reed Switches

Go to FAQs about Reed Sensors

Go to FAQs about Reed Relays

Go to FAQs about Level Sensors

Go to FAQs about Test & Operate Characteristics

Go to FAQs about Quality & Reliability

Can't find the answer for your question in our FAQ's? Please use our  contact form to submit a new question.




New Catalog - 2014

Tutorials - Audio Version

3-D Magnetic Mapping
Magnet Interactions
Magnet Technology & Uses
Latching Sensors & Relays
Liquid Level Sensing
Reed, Hall & EM Overview
Reed Switch Technology
Reed Relay as RF Switch Part 1
Reed Relay as RF Switch Part 2

Mini-Glossary

Form A = normally open contact (N. O.)
Form B = normally closed contact (N.C.)
Form C = change over contact (S.P.D.T.)
Form E = Bistable / Latching
AT = Ampere Turns; Parameter that describes magnetic sensitivity.

Magnet Resources

Magnetization Guide
Magnet guide of magnetization and magnet applications.

Magnet Specifications
Magnet characteristics: shape, dimmension, flux density, magnetic material.

Magnet Handling
Proper magnet handling techniques.