Honeywell Hall Effect
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|Honeywell Micro Switch|
Hall Effect Switch
Everett A. Vorthmann|
Joeseph T. Maupin
|Contact mechanism||Hall effect|
|Peak force||45 cN? to 140 cN?|
Introduced sometime in the early 1980s or late 1970s, Micro Switch (a division of Honeywell) adapted their hall effect switch technology to work in keyboards. These switches are among the highest quality ever produced by any keyboard switch company, with reliability being paramount to their design. For increased reliability, there are both 3 pin and 4 pin designs of the switch, the later with dual sense lines for redundancy. The patent itself originates from 1969, but the design is aesthetically very different from the produced switches.
The Honeywell Hall Effect switch is most famous on some Symbolics keyboards, as well as the Space-cadet keyboard.
Features (as per Honeywell)
Details for switch Model 4A3A which should be consistent across all models, except for operating force:
- Total Travel - 0.160 in (4.1 mm) nom.
- Force at operating point - 2.8 oz. (78 g) nom.
- Pretravel - 0.090 in. (2.3 mm) nom.
- Release point at 5 VDC and 75°F (24°C) (With respect to free position) - 0.040 in. (1.0 mm) min.
Smooth linear switch, makes Cherry MX Black switches feel like they have sand paper on the stems.
Honeywell Hall Effect keycaps are known to be exclusively double-shot, using very thick plastic in all cases.
Some keycaps have some odd properties such as this Caps Lock LED keycap (Switch Model 12B3S):
Honeywell hasn't been making these switches since the early 1990's and has been out of the keyboard business since then, so it's probably impossible to source them. Keyboards with the switches do show up occasionally on auction sites like Ebay, but this isn't always obvious, and they most certainly don't work with modern computers without a converter. The last known keyboard with these switches was made in mid 1996 for Sun Microsystems.
While the switch isn't in production anymore, there were many variants of the switch, with a specific naming scheme to the models.
In almost all standard variants of the switch, there is a spot for a LED add-on part as seen in the Convergent 64-00164 keyboard.
As a regular expression, the models can be shown as such (not yet confirmed from Honeywell datasheets): ([0-9]+)([A-Z])([0-9])([A-Z])
- ([0-9]+) Switch variant
- 1 - White stem
- 4 - Black stem
- 5 - Black stem, locking mechanism
- 6 - Short black stem
- 12 - LED keycap stem
- 16 - Alternate keyboard mount (Link)
- ([A-Z]) Stem type
- A - Straight stem
- B - Angled stem
- T - Angled stem, ridged housing
- ([0-9]) Switch weighting
- 1 - Light (45cn?)
- 3 - Normal (78cn)
- 8 - Heavy (140cn?)
- ([A-Z]) Switch type
- A - 4 pins, 2 [redundant] sense lines (Unknown difference from S)
- D - Dummy (no pins)
- E - 3 pins, 1 sense line
- S - 4 pins, 2 [redundant] sense lines (Unknown difference from A)
Confirmed variants of the switch:
- 1A3S - TI Telex 58SD17-2-B
- 1A8S - TI Telex 58SD17-2-B
- 4A1E - Burroughs TP130
- 4A3A - Bud Keypad 83959
- R4A3E - Burroughs TP130 (Meaning of the R is unknown)
- 4A8E - Burroughs TP130
- 4B1D - Convergent 64-00164
- 4B1E - Space-cadet
- 4B1S - Convergent 64-00164
- 4B3E - Symbolics 3600 Rev D, Space-cadet
- 4T3S - Convergent 64-00164
- 5A3E - Burroughs TP130
- 6A1D - Convergent 64-00164, Burroughs TP130
- 6B1D - Convergent 64-00164, Space-cadet
- 12B3S - Convergent 64-00164
- 16B3E - Sun 32SD38-4-E