Editing Keystroke sensing (section)

===Hall effect===
{{Main|Hall effect keyboard}}

Hall effect keyboards use a solid state sensor (in a microchip found inside each switch) to detect the movement of a magnet by the potential difference (voltage) that the magnet creates across a wire. A typical implementation of a Hall effect switch consists of a linear switch which has a magnet attached to the slider, whose movement when the key is pressed actuates the switch. They are extraordinarily reliable, with an expected lifetime measured in billions of key presses. However, they are too expensive for general use, and are usually reserved for military and aerospace applications.

Hall effect keyboards use discrete switches just as with most metal contact keyboards, but the switch modules typically have four legs instead of the two or three in metal contact switches. Four-leg switches are good indication of either Hall effect or magnetic valve.

[[Honeywell]] is by far the best known manufacturer of Hall effect keyboard switches and switches through their Micro Switch division. Similar switches were also made in Eastern Europe during the Soviet era, often copies of Honeywell's switches. [[RAFI]] in Germany still manufacture their long-standing [[RAFI RS 76 C|RS 76 C]] series of Hall effect keyboard switches.

<gallery widths=250 heights=187>
File:Micro Switch 15SD15-1-E top view.JPG     | [[Micro Switch SD Series]] switches
File:RAFI-RS76C-disassembled.jpg              | RAFI RS 76 C switch disassembled, showing the Hall sensor IC; the magnet is inside the slider
</gallery>

See: [[:Category:Hall effect switches|List of Hall effect switches]]