Magnetic, Reed Switches

Part Number	Description / PDF	Quantity
MDCG-4-12-18 Wickmann / Littelfuse	SWITCH REED SPST-NO 350MA 140V	34625
MLRR-3-17-28 Wickmann / Littelfuse	SWITCH REED SPST-NO 700MA 140V	0
ORD 213/20-30 AT Standex Electronics	SWITCH REED SPST-NO 100MA 24V	1210
MDCG-4-12-33 Wickmann / Littelfuse	SWITCH REED SPST-NO 350MA 140V	1801
KSK-1A85-3040 Standex Electronics	SWITCH REED SPST-NO 1A 1000V	0
59166-1-T-00-C Wickmann / Littelfuse	SWITCH REED SPST-NO 350MA 140V	0
MLRR-3-22-33 Wickmann / Littelfuse	SWITCH REED SPST-NO 700MA 140V	0
SW GP560/20-25 AT Standex Electronics	SWITCH REED SPST-NO 1A 125V	3720
ORD 311/10-15 AT Standex Electronics	SWITCH REED SPST-NO 1A 100V	1987
59050-030 Wickmann / Littelfuse	SWITCH REED SPDT 250MA 175V	475
MS-108-5-4 PIC GmbH	MAINS SWITCHING REED SENSOR PITC	170
MDSR-4-17-23 Wickmann / Littelfuse	SWITCH REED SPST-NO 500MA 200V	0
59045-1-T-00-0 Wickmann / Littelfuse	SWITCH REED SPST-NO 350MA 140V	1351
SW PR560/30-35 AT Standex Electronics	SWITCH REED SPST-NO 1A 250V	0
59166-1-S-00-D Wickmann / Littelfuse	SWITCH REED SPST-NO 350MA 140V	0
MDCG-4-12-28 Wickmann / Littelfuse	SWITCH REED SPST-NO 350MA 140V	0
MK23-35-B-1 Standex Electronics	SWITCH REED SPST-NO 1A 200V	0
MISM-7B-15-20 Wickmann / Littelfuse	SWITCH REED 7MM 15-20AT 10W SMD	0
MLRR-3-17-23 Wickmann / Littelfuse	SWITCH REED SPST-NO 700MA 140V	0
MK02/6-0 Standex Electronics	SWITCH REED SPST-NO 500MA 170V	0

Magnetic, Reed Switches

1. Overview

Magnetic reed switches are electromechanical switching devices operated by an applied magnetic field. Comprising ferromagnetic contacts sealed in a glass envelope, they enable contact closure (or opening) without physical actuation. Their hermetically sealed design ensures reliability in harsh environments, making them critical components in modern automation, security systems, and industrial equipment.

2. Main Types & Functional Classification

Type	Function	Application Example
Normally Open (NO)	Contacts open without magnetic field	Door/window sensors in alarm systems
Normally Closed (NC)	Contacts close without magnetic field	Emergency shut-off systems
Change-over (CO)	Three-contact configuration with common terminal	Industrial process control systems
High-Voltage Reed Switch	Rated for >1kV applications	Medical imaging equipment

3. Structure & Composition

Typical structure includes:

Hermetically sealed borosilicate glass capsule
Electroplated ferromagnetic nickel-iron contacts (0.1-0.2mm thickness)
Inert gas atmosphere (usually nitrogen or argon)
External magnetic actuation source (permanent magnet or electromagnet)

Advanced variants feature sputtered ruthenium/tungsten coatings for improved contact durability.

4. Key Technical Parameters

Parameter	Typical Range	Significance
Contact Rating	10VA - 200VA	Determines switching capacity
Operate Time	0.2 - 2.0ms	Response speed for fast-switching applications
Dielectric Strength	100V - 10kV	Electrical insulation capability
Operational Life	10⁶ - 10⁹ operations	Long-term reliability indicator
Actuation Distance	1 - 50mm	Design flexibility for mechanical systems

5. Application Fields

Consumer Electronics: Smart home sensors, wearable devices
Automotive: Transmission position sensors, anti-theft systems
Industrial: Flow meters, valve position monitoring
Medical: MRI machine interlocks, infusion pump controls
Security Systems: Window/door intrusion detection

6. Leading Manufacturers & Products

Manufacturer	Product Series	Key Features
TE Connectivity	KB Series	10⁹ operations life, aerospace qualified
Omron	Reed Relays G6K	Subminiature size (10.5mm), 24VDC rating
Honeywell	919H Series	High-voltage (3000VAC), medical-grade insulation
Hamlin	Hermetic Reed Switches	IP68 rating, -55 C to +125 C operating range

7. Selection Guidelines

Key considerations:

Contact configuration (NO/NC/CO) matching control circuit requirements
Environmental factors: Temperature (-40 C to +150 C typical), vibration resistance
Electrical parameters: Must exceed 20% of application requirements
Actuation method: Fixed magnet position vs. movable magnet systems
Mounting orientation: Axial vs. radial mounting constraints

Case Study: Smart meter applications require reed switches with >10⁸ operations life and anti-tamper certification.

Industry Trends

Emerging developments include:

Micro-scale reed switches for IoT devices (under 3mm size)
Integrated Hall effect sensor combinations
Graphene-coated contacts for ultra-low resistance (0.01 typical)
Wireless reed switch modules with BLE connectivity
Increased adoption in renewable energy systems for contactor control