Jump to page content

Micro Switch SN Series



SW and SN Series are Micro Switch’s original series of Hall effect pushbutton switches.

SN Series is the standalone equivalent to SW Series. SN Series comprises the self-contained switches with sealed bases. These switches could be snapped into a panel, or affixed to the PCB by adhesive pads prior to soldering. A base is fitted to the switch to contain the internal parts. The base notwithstanding, SN Series switches are externally identical to SW Series switches, and they use many of the same components.

The base for SN Series makes use of cutouts in the shell that provide clearance around the securing rails of SW Series keyboards. From this, it is not clear if SW and SN were conceived together, or whether SN was added shortly afterwards, taking advantage of the cutouts in SW switches as a way to attach the base. The base is noted in 201SN Chart 2 to be ultrasonically welded to the shell. The base is primarily attached by two internal clips, and then welded. With sufficient force, the base can be prised off.


Switches in SN Series fall into numerous subseries:

Subseries Mount Type Terminals
1SN Series Snap-in panel mount Non-illuminated confirmed Special terminal layout
11SN Series Snap-in panel mount Illuminated and non-illuminated Quick connect
20SN Series Not observed
101SN Series Self-adhesive PCB mount Non-illuminated PCB solder terminal
105SN Series Not observed
108SN Series Self-adhesive PCB mount Non-illuminated PCB solder terminal
115SN Series Not observed
125SN Series
150SN Series
151SN Series
155SN Series
160SN Series
201SN Series Self-adhesive PCB mount Illuminated, with optional lamp PCB solder terminal
205SN Series Not observed
211SN Series
225SN Series
250SN Series
260SN Series
501SN Series

A 1SN product sheet was advertised in 1970, but not seen; 1SN is described as “developed for keyboards.” The two 1SN examples observed to date (1SN1 and 1SN31) each have a PCB riveted to an SW-style securing frame, that provides a completely different terminal layout, with each terminal relocated to one of the four corners of the switch. The terminals are the style found on miniature snap-action switches, not the more conventional PCB solder terminals. 1SN switches still have the snap-in panel mount.

In Computerworld, May 10, 1972 on page 28, Micro Switch announced that they would be demonstrating (amongst other things) their solid state keyboards and general-purpose solid state switches at the Spring Joint Computer Conference in Atlantic City, New Jersey (15th to 19th of May 1972). This is the earliest mention to date of 101SN and 201SN switches. A single keyboard model, 75SW12, is also mentioned in the magazine, as well as SS series general purpose solid-state switches including the then-new 15SS current sink type.

101SN is non-illuminated and 201SN is illuminated, and these are the series of which the PCB-mount switches are normally found. The only known instance of 108SN, specifically 108SN11, outwardly appears to be the same as 101SN, with the differences to 101SN being a mystery. Honeywell’s charts for 101SN and 201SN suggest that at least some models used quick connect terminals (although no such switches have been seen yet); the specifics of each of the various subseries remain very unclear.

11SN illuminated and 201SN switches are centre-lit within a cylindrical plunger, and thus require special keycaps. Lamps were optional: there were separate part numbers based on whether or not a lamp was included.

Switches use either an SW packaged sensor unit (as widely observed in SW Series) or an SD sensor PCB, shared with SD Series. The types with packaged sensor units have two magnets, one on either side of the sensor. The types with a sensor PCB use taller magnets; the charts only show the one magnet, but nonetheless indicate that two are present.

In 2020, Honeywell located charts for the following additional SN subseries, but never had time to make them available: 20SN Series, 105SN Series, 108SN Series, 115SN Series, 125SN Series, 150SN Series, 151SN Series, 155SN Series, 160SN Series, 205SN Series, 211SN Series, 225SN Series, 250SN Series, 260SN Series and 501SN Series.


SN series uses two separate schemas; the reason for this split is not known.

Non-illuminated types

Non-illuminated SN models use a numeric model number arrangement very similar to that of SW Series. It appears that odd-numbered switches are sloped and even-numbered switches are stepped, as with SW Series.



Prefix for snap-in panel mount non-illuminated subseries
Prefix for PCB-mount non-illuminated subseries
Series name
Model number

Illuminated types

Illuminated SN models use a structured model number arrangement similar to that of SD Series. The sensor type codes appear to be the same as for SD series, while the switch type codes are different.



Prefix for snap-in panel mount illuminated subseries
Prefix for PCB-mount illuminated subseries
Series name
Type: 1 = momentary standard force, 2 = alternate action, 3 = uncertain, 4 = low force momentary, 5 through 9 uncertain
Output: A = sink level, B = sink pulse, C = source level, D = none (dummy), S = logic scan
Lamp: 1 = no lamp fitted, 2 = lamp fitted

The nature of types 3, 5, 6, 7 and 9 is not clear, as the bill of materials for each type does not indicate the spring weights or sensor types. Once this information is obtained, these types will be better understood.


11SN switches have used both the old sequential numbering system as well as the later schematic numbering system. Just as with 1SW, some models were made obsolete within the lifetime of the series, and the model numbers were deleted from the charts. The encircled letters are verbatim from Honeywell’s charts and indicate the revision of the chart in which that model was removed, with some removals being great enough that the removed types were not listed out, causing the model numbers to be lost.

Catalogue listing Action Mount Lamp Force Sensor Circuit function Plunger style NSN Notes
1SN1 Snap-in Sloped Black plunger; eBay (7147)
11SN31 Snap-in Sloped Black plunger; eBay (7251)
11SN1 Momentary Snap-in SW-11921 5930-00-148-2715
11SN3 Alternate action Snap-in SW-11921 5930-00-148-2716
11SN11 5930-01-215-8693
11SN15 Momentary Snap-in SW-11921
11SN17 Momentary Snap-in SD-10023 Sink pulse 5930-01-042-6338
11SN19 Momentary Snap-in SW-11921
11SN21 Momentary Snap-in SD-10575 5930-01-014-4851
11SN23 Alternate action Snap-in SW-11920
11SN31 Momentary Snap-in SD-10575
11SN33 Momentary Snap-in SW-11920
11SN33MR Momentary Snap-in SW-11920
Momentary Snap-in SW-12563
11SN51 Support Snap-in
11SN1A1 Momentary Snap-in Not supplied SD-10575 5930-01-028-9539
11SN1A1PC 5930-01-240-8958
11SN1A2 Momentary Snap-in Supplied SD-10575 5930-01-011-4779
Momentary Snap-in Supplied SW-11920
Momentary Snap-in Supplied SW-12563
Momentary Snap-in Not supplied SW-12563
Momentary Snap-in Supplied SW-11920
Momentary Snap-in Not supplied SD-10023 Sink pulse
11SN1B2 Momentary Snap-in Supplied SD-10023 Sink pulse 5930-01-013-4513
11SN1C1 Momentary Snap-in Not supplied SW-11921 5930-01-363-5267
11SN1C2 Momentary Snap-in Supplied SW-11921
11SN2A1 Alternate action Snap-in Not supplied SW-11920
11SN2A2 Alternate action Snap-in Supplied SW-11920
11SN2C1 Alternate action Snap-in Not supplied SW-11921 7025-01-359-9992
11SN2C2 Alternate action Snap-in Supplied SW-11921
11SN3D1 Indicator (sprung) Snap-in Not supplied
11SN3D2 Indicator (sprung) Snap-in Supplied
101SN1 PCB 5930-00-320-7253
101SN11 PCB Sloped 5930-01-035-0807 Black plunger; eBay
101SN12 PCB Stepped Black plunger; eBay (7449)
101SN17 PCB 5930-01-082-0218
101SN25 PCB Black plunger; eBay (7449)
101SN51 PCB Sloped Black plunger, slot type for wide keys; eBay
101SN53 PCB Sloped Black plunger, slot type for wide keys
101SN55 PCB 5930-01-041-4326
201SN1A1 Momentary PCB Not supplied Sink level 5930-01-013-3788
201SN1A2 Momentary PCB Supplied Sink level 5930-01-070-8475
201SN1B1 Momentary PCB Not supplied SD-10023 Sink pulse 5930-01-025-9323
201SN1B2 Momentary PCB Supplied SD-10023 Sink pulse 5930-01-231-2011
Momentary PCB Not supplied Sink pulse
Momentary PCB Supplied Sink pulse
Momentary PCB Not supplied Source level
Momentary PCB Supplied Source level
201SN2A2 Alternate action PCB Supplied 5930-01-044-4303
201SN3D1 Momentary PCB Not supplied ca. 1 N Indicator
201SN3D2 Momentary PCB Supplied ca. 1 N Indicator 6210-01-092-1366
201SN4A1 Momentary PCB Not supplied Low force Sink level
201SN4A2 Momentary PCB Supplied Low force Sink level
Momentary PCB Not supplied Low force Sink pulse
Momentary PCB Not supplied Low force Source level
Momentary PCB Supplied Low force Source level
201SN5D1 Momentary PCB Not supplied Low force Dummy
201SN5D2 Momentary PCB Supplied Low force Dummy 6210-01-034-6482
Momentary PCB Not supplied Low force Sink level
Momentary PCB Supplied Low force Sink level
Momentary PCB Not supplied Indicator Plunger permanently positioned in free position
Momentary PCB Not supplied Indicator Plunger permanently positioned in alternate action actuated position
Momentary PCB Not supplied High force Sink [sic]
Momentary PCB Not supplied Scan
Alternate PCB Not supplied Sink level
Alternate PCB Supplied Sink level
Alternate PCB Not supplied Source level
Alternate PCB Supplied Source level

At present there is no “M” chart for 101SN.


Equipment using SN series switches is rarely encountered. So far, the following have been discovered:

Equipment Description Switches
Kenway E3 1901 F 69-station MC-8 Terminal keyboard 101SN7, 201SN2A1, dummy
Kenway 2-9907 27-station MC-8 control panel Illuminated and non-illuminated
Eaton Kenway D3-5828 36-station control panel Illuminated and non-illuminated
CDC 9427H cartridge disk drive Front panel controls 201SN1A2, 201SN2A2, 201SN3D2 (parts information from Ramon Cases Jové)
Norland 3001 81-station processing digital oscilloscope 101SN11, 101SN53


Honeywell have kindly provided a collection of SN Series switch charts. The charts themselves were extensively redacted by Honeywell as switches went end-of-life, but they do have some older versions of the charts, and with luck, they may find some more older revisions with more switch details.

See also