MK4 Series

Magnetically operated Reed Sensor with mounting holes for screw fastening


MK4 sensors are magnetically operated Reed proximity switches designed for screw mounting. The sensor should be mounted on a fixed surface with the actuating magnet, e.g. M4, on the moving surface.  The Reed Sensor and magnet must be fixed in a definite distance to each other.  Approximation resp. removal of the magnet determines the closing and opening of the Reed Switch.  The magnetic pull-in / drop-out sensitivity is divided into five AT ranges.  A choice of switches, termination options and cable lengths is offered.


Position- and limit switch, e.g. pneumatic or hydraulic actuator position indication and end travel limit switch

Door and window contacts for security system applications

Level Sensor use with magnetic floats for water level detection e.g. coffee-makers, washing-machines, dish-washers


Tolerance +/- 0.10mm (0.004 inch)

Dimension Drawing


The standard termination is a two-wire flat cable with a cross section of 2 x 0.14mm². The standard length of the cable is 500mm, other lengths can be supplied on request. The required length has to be noted on the part number. The cable end can be supplied with the following connection styles (please note after the length in the part number).

W Cable end cut, dismantled on 30 mm, cores stripped and tinned on 5 mm (0.2inch)
X Individual crimped terminals 1mm(0.04inch) diameter
Y Individual spade terminals, 2.8 x 0.8mm(0.11 x 0.03inch)
Z  “MASCON” sleeve suitable for pcb connector with 2.54mm(0.1inch) pitch

Contact Data

Contact type 71 81 84 90
Contact form A/dry A/dry A/dry B/C/dry
Rated Power max. (W) 10 5 10 3
Switching voltage max. (VDC) 1801 90 400 175
Switching current max. (A) 0.5 0.5 0.5 0.25
Carry current (A) 1.02 1.0 1.0 1.2
Contact resistance max. mOhm 150 200 150 150
Breakdown voltage (contact/contact) min. (VDC) 2103 100 700 200
Operating time incl. bounce (ms) 0.5 0.5 0.5 0.7
Releasing time (ms) 0.1 0.1 0.1 1.0
Operating temperature (°C) -20/+85 -20/+85 -20/+85 -20/+85
Storing temperature (°C) -35/+85 -35/+85 -35/+85 -35/+85

1Range D & E: 200 VDC  2Range D & E: 1.75 A  3Range

Other switches by request.

Magnetic Sensitivity

Sensitivity class A B C D E
Pull-in AT range 5-10 10-15 15-20 20-25 25-30
Available switches 81 71 71/84/90

This data relates to unmodified Reed switches before mounting. Please refer to the respective single data sheets for sensitivity data and measurement methods for finished assemblies.

Order information

Ordering example

MK4 – 1A71 C – 500 W

MK4 Reed Sensor, 1 form A switch type 71, Sensitivity class C, Cable length 500mm, Termination W

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