Development of a Degausser

(System for erasuring magnetic recorded data)

Degaussers are devices with a strong magnetic field for erasuring magnetic stored data in hard disc drives and magnetic tapes.
The requirements to the strength and spatial dimension of this field are derminated by

  • the properties of the hard magnetic storage layers and
  • the geometric dimensions of the data media (hard discs drive, magnetic tape cassettes)

In general magnetic air-fields are generated

  • in air coils by current pulses from capacitor discharges or
  • in the air gap of yokes

A powerful degausser with a magnetic field in the air gap of a yoke with electromagnetic excitation was developed by Magnettechnik Kleine. 
A flux density of B ≥ 1.2T is achieved within a rectangular volume

  • over a width (perpendicular to the field direction) of 100mm and
  • a length (along the field direction) of 30mm

The value of B is determined with HALL sensors on several tracks during the transport of the data-media through the field.
The degausser is operated by a touchscreen. As power supply a 230V-net (16A) is sufficient. 

The developed degausser can be converted  to a system for other tasks by a few changes / additions, such as for 

  • the determination of the specific saturation magnetisation σS according to IEC 60404-14
  • to magnetising hard magnetic ferrites

(see passage “own solution”).

The field strength can be clearly increased for these applications by reduction of the air gap size.