Do magnetic control keys still function and have value in access control systems – are they the same as magnetic slugs?
A: Magnetic keys aren’t the same as magnetic slugs. With magnetic keys, rare earth magnets are permanently embedded in a coded pattern into a shaped blank made of a very tough nylon material. The readers use Hall effect devices to read the bit pattern (position of the magnets) in the key. Magnetic keys are an Australian design used by both Mil and DKS since 1972 and 1974 respectively.
Comparatively, magnetic slugs or metal pieces are embedded or layered in a card and are read by magnetic sensing devices. Also known as a shim card and generally limited to single code stand-alone applications. The reader required no power, and the output was a microswitch. These were very primitive, and it would be most unlikely that there are many still in service. Corkey was one brand sold in Australia in the late 70s*.
There are magnetic key readers still in operation, though they are becoming quite rare now, and in certain applications they remain functional. The monitoring and reporting functions of legacy systems like these are where they fall very far behind the latest solutions.
* Thanks to Roger Pearce for these technical descriptions…