Micro Switch SD Series

This article requires restructuring — the content relating to SW and SN series needs moving to the respective pages; also, this page is chaotic; also, use of a regular expression for model numbering is pretty brutal (now we have two problems ......)

This article requires additional photographic illustration — family portrait for infobox; dedicated variants table images

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Warning Please be aware that the material on this page is unverified and may not be correct: known variants list is almost entirely redlinks!

Micro Switch SD Series

Manufacturer	Micro Switch
Inventor	Everett A. Vorthmann Joeseph T. Maupin
Supersedes	Micro Switch SW Series
Switch type	Linear, Tactile
Sense method	Hall effect
Rated lifetime	Tested up to 30 billion (extremely long)
Peak force	45 g to 320 g[Citation needed]

History

Honeywell Hall Effect switches are advertised and tested to be a switch with an incredibly long lifetime, and designed with reliability in mind. There are both three and four pin designs of the switch, depending on the type of sensor. The four pin sensors are +5, GND and dual open-collector outputs, allowing wired-or of the X, Y keyboard matrix. The switches are naturally bounce free due to the sensing method.

The Honeywell Hall Effect switch is well-known for it's use on some Symbolics keyboards, as well as the Space-cadet keyboard.

The last accessible reference to SN and SD series on the Honeywell website is from the 22nd of February 1999.<ref name="IAWM-SD-SN" /> The products list at this time were:

• Hall-Effect Keyboards Sales Sheet (02509_a.pdf)
• SD16 Keyswitch Modules Product Sheet (02503_0.pdf)
• 63SD30-4 Microcomputer-based Keyboard Product Sheet (02504_0.pdf)
• 26SD1-2 Point-of-Sale Keyboard Product Sheet (02506_0.pdf)
• 12SD/16SD Numeric Keyboards Product Sheet (02607_0.pdf)

The PDF documents were not archived. Later that year, Honeywell redesigned their website such that it could no longer be crawled (product data was accessible through form submission), so it is not clear when SD and SN series were phased out.

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.

Note that according to the 1998 1001SD Series Chart 2 (listed within Micro Switch SD16 Keyswitch Modules, below) this should be 0.695 N/2.5 oz, so the specifications may have changed over time.

Part Numbers

Micro Switch and Honeywell switches typically have the series name within the part number, which was apparently notably not the case for SD Series. According to the 1998 1001SD Series Chart 2, the part numbers are of the form 1001SDnnnn, where the four-character "identification code" is all that is printed on the switch, for brevity.

As a regular expression, the models can be shown as shown below. Descriptions given in italics are observations not corroborated with Micro Switch documentation.

According to the datasheet, "sloped" switches have upright stems: the description refers to how a tilted keyboard the keycap top surfaces will be sloped. Angled stem switches are called "stepped" due to the presentation of a staircase profile in a tilted keyboard.

([A-Z])?([0-9]+)([A-Z])([0-9])([A-Z])

1. ([A-Z])? Sensor variant? (All sensor PCBs with this code have this printed on it)
   • D - ?
   • Q - ?
   • R - ?
   • T - ?
2. ([0-9]+) Switch variant
   • 1 - Unknown (white stem)
   • 4 - Momentary action (black stem)
   • 5 - Alternate action (black stem)
   • 6 - Support (short black stem)
   • 10 - External latching, used on both caps lock and shift on some keyboards.
   • 11 - Black stem, tactile
   • 12 - LED keycap stem
   • 16 - Alternate keyboard mount<ref name="MouseFan_altmicro" />
3. ([A-Z]) Stem type
   • A - Sloped (non-angled)
   • B - Stepped (angled)
   • F - No keycap stem
   • G - Flat top
   • H - Flat-stepped
   • K - Narrow bar stem
   • S - Sloped
   • T - Stepped (ridged housing)
4. ([0-9]) Switch weighting (hard to read in the datasheet; some figures are best guesses)
   • 1 - 0.362 N/1.1 oz
   • 2 - 0.556 N/2.0 oz
   • 3 - 0.695 N/2.5 oz
   • 5 - 0.973 N/3.5 oz
   • 6 - 1.668 N/6.0 oz
   • 8 - 2.224 N/8.0 oz
   • 4 - No spring (use with three unit button)
5. ([A-Z]) Switch output
   • A - Sink level (4 pins, 2 redundant sense lines)
   • B - Sink pulse
   • C - Source level
   • E - 3 pins, 1 sense line
   • K - Timed repeat (4 pins, 2 redundant sense lines)
   • S - Logic scan (4 pins: +5, OUT, IN, GND)
   • D - None

Known Variants

Variants are listed in order of part number. The extra character found at the start of some part numbers is treated separately for the purposes of sorting; for example D1K3S is listed after 1K3S.

	Number	Action	Keystem	Weight	Signal	Known usage
	1A3A	Momentary	Square, sloped	2.5 oz	Sink level	Micro Switch 68SD15-1-E
	1A3B	Momentary	Square, sloped	2.5 oz	Sink pulse	Micro Switch 68SD15-1-E
	1A3S	Momentary	Square, sloped	2.5 oz	Logic scan	TI Telex 58SD17-2-B, TI Silent 700 Model 745 (63D17-3-B)
	1A8S	Momentary	Square, sloped	8.0 oz	Logic scan	TI Telex 58SD17-2-B, TI Silent 700 Model 745 (63SD17-3-B)
File:No photograph.svg	1B3S	Momentary	Square, stepped	2.5 oz	Logic scan	Nokia MikroMikko 1 keyboard
File:No photograph.svg	1F5A	Momentary	None	3.5 oz	Sink level	UGC-74 Keyboard
File:No photograph.svg	1K3S	Momentary	Bar	2.5 oz	Logic scan	Bunker Ramo ADMIN 20211322
	D1K3S	Momentary	Bar	2.5 oz	Logic scan	Bunker Ramo ADMIN 20403025
File:No photograph.svg	2K3S	Momentary	Bar	2.5 oz	Logic scan	Bunker Ramo ADMIN 20403025
File:No photograph.svg	4A1A	Momentary	Square, sloped	1.1 oz	Sink level	Honeywell 26SD1-2-H
File:No photograph.svg	4A1E	Momentary	Square, sloped	1.1 oz	?	Burroughs TP110, Burroughs TP130, Burroughs RIII
File:No photograph.svg	T4A2B	Momentary	Square, sloped	2.0 oz	Sink pulse	Wang 271-1126 (Meaning of T is unknown)
File:No photograph.svg	4A2K	Momentary	Square, sloped	2.0 oz	Timed repeat	Wang 271-1126
File:No photograph.svg	4A3A	Momentary	Square, sloped	2.5 oz	Sink level	Bud Keypad 83959, Honeywell 26SD1-2-H
File:No photograph.svg	Q4A3B	Momentary	Square, sloped	2.5 oz	Sink pulse	Wang 271-1126 (Meaning of Q is unknown)
File:No photograph.svg	4A3E	Momentary	Square, sloped	2.5 oz	?	Burroughs TP110
File:No photograph.svg	R4A3E	Momentary	Square, sloped	2.5 oz	?	Burroughs TP130 (Meaning of the R is unknown)
File:No photograph.svg	4A8E	Momentary	Square, sloped	8.0 oz	?	Burroughs TP110, Burroughs TP130
	4B1D	Momentary	Square, stepped	1.1 oz	None	Convergent 64-00164, Telex 278
	4B1E	Momentary	Square, stepped	1.1 oz	?	Space-cadet, Telex 278, Burroughs RIII
File:No photograph.svg	4B1S	Momentary	Square, stepped	1.1 oz	Logic scan	Convergent 64-00164
File:No photograph.svg	4B2E	Momentary	Square, stepped	1.1 oz	?	Burroughs RIII
	4B3E	Momentary	Square, stepped	2.5 oz	?	Symbolics 3600 Rev D, Space-cadet, Telex 278
File:No photograph.svg	4B3K	Momentary	Square, stepped	2.5 oz	Timed repeat	Wang 271-1126
4B3S	4B3S	Momentary	Square, stepped	2.5 oz	Logic scan	Intergraph 2710
File:No photograph.svg	4T3S	Momentary	Stepped	2.5 oz	Logic scan	Convergent 64-00164
File:No photograph.svg	5A3E	Alternate	Square, sloped	2.5 oz	?	Burroughs TP110, Burroughs TP130
File:No photograph.svg	6A1D	Support	Square, sloped	1.1 oz	None	Convergent 64-00164, Burroughs TP110, Burroughs TP130, Burroughs RIII
	6B1D	Support	Square, stepped	1.1 oz	None	Convergent 64-00164, Space-cadet, Honeywell 26SD1-2-H, Telex 278, Burroughs RIII
	9B3B	Momentary	LED support	?	?	SD-16073
	12B3S	Momentary	LED support	2.5 oz	?	Convergent 64-00164
File:No photograph.svg	10B2E	Momentary	Square, stepped	2.2 oz	?	Burroughs RIII
File:No photograph.svg	16B3E	Momentary	Alternate, stepped	2.5 oz	?	Sun 32SD38-4-E

Availability

SD Series appear to have gone out of production circa 1999 or 2000. Keyboards with the switches occasionally appear on auction sites such as Ebay, but it is not always obvious. Nearly all keyboards using Microswitch SD require a converter. The last known keyboard with these switches was made in mid 1996 for Sun Microsystems. Further research has shown that Honeywell has been using their "dual magnet" design to make backlit switches for industrial keyboards as recently as 1999.^{[Citation needed]}

Electrical Characteristics

Controller Sensing Characteristics

Switch Dimensions

Documentation

• Micro Switch SN/SD Series
• Micro Switch SD16 Keyswitch Modules (with 1001SD Series Chart 2)

Keyboards

• Burroughs TP110<ref name="TP110"/>
• Burroughs TP130<ref name="TP130"/>
• Burroughs RIII<ref name="burroughs"/>
• Convergent Technologies CT 64-00164<ref name="Convergent"/>
• Datagraphix 132B<ref name="data"/>
• Micro Switch SD-16255<ref name="SD16255"/>
• Nokia MikroMikko 1<ref name="Nokia"/>
• Pertec XL40 keyboard
• Selenia Tina 270 78<ref name="selenia"/>
• Space-cadet keyboard
• Some Symbolics 364000
• Telex 270 keyboards
• Texas Instruments TI Silent 700 Model 745
• UGC-74<ref name="UGC"/>
• Wang 271-1126<ref name="Wang"/>

Typewriters

• Honeywell 70SD22-4 typewriter module (Tactile)<ref name="tactile"/>

Keypads

• Bud 83959<ref name="Bud"/>
• Sun 32SD38-4-E<ref name="Sun"/>

External Links

• dork_vader_exe — Hall Effect Switch Compendium switches Retrieved 2016-02-14.
• dork_vader_exe — Hall Effect Switch Compendium keycaps Retrieved 2016-02-14.
• Google — Honeywell Keypad Datasheet Retrieved 2015-07-27.
• MouseFan — SUN 32SD38-4-E USA — Last known manufactured Honeywell Hall Effect switch (Japanese only). Last updated 2004-05-02. Retrieved 2015-07-27.
• Honeywell.com — Technical document on Honeywell Hall Effect switches Retrieved 2015-07-27.

References

<references> <ref name="MouseFan_altmicro">MouseFan — SUN 32SD38-4-E USA (Japanese only) Last updated 2004-05-02. Retrieved 2018-01-23.</ref> <ref name="IAWM-SD-SN">(Wayback Machine) Honeywell.com — Hall-Effect Keyboards Archived 1999-02-22.</ref> <ref name="Convergent">Deskthority — Convergent Technologies CT 64-00164 Micro Switch Vintage Keyboard Serial Output Posted 2020-12-10.</ref> <ref name="TP130">Deskthority — Burroughs TP130 Posted 2012-08-09.</ref> <ref name="Wang">Imgur — wang keyboard Uploaded 2015-11-07.</ref> <ref name="TP110">Deskthority — Burroughs TP110 keyboard Posted 2018-05-01.</ref> <ref name="UGC">Deskthority — UGC-74 Keyboard Posted 2014-09-13.</ref> <ref name="Sun">Mousefan — Sun 32SD38-4-E USA 1996 Accessed 2022-04-10.</ref> <ref name="Bud">Geekhack — Bud/Honeywell Hall Effect Keypads (~30) Posted 2011-05-13.</ref> <ref name="Nokia">Imgur — Nokia MikroMikko 1 keyboard Uploaded 2013-11-29.</ref> <ref name="data">YouTube — Datagraphix 132B Keyboard Typing Demo Uploaded 2022-06-28.</ref> <ref name="tactile">Deskthority — Tactile Micro Switch SD typewriter module w/ secretarial shift 70SD22-4 Posted 2022-07-07.</ref> <ref name="SD16255">Imgur — Micro Switch SDR SD-16255 EIA349-1-0 Uploaded 2022-08-06.</ref> <ref name="selenia">Deskthority — SELENIA TINA 270 78 Key Posted 2019-11-27.</ref> <ref name="burroughs">Deskthority - NOS Micro Switch SD Keyboard - 1981 - Burroughs RIII Keyboard Posted 2022-12-06.</ref> </references>