Micro Switch SN Series
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 at least three subseries:
|11SN Series||Snap-in panel mount||Illuminated and non-illuminated|
|101SN Series||Self-adhesive PCB mount||Non-illuminated|
|201SN Series||Illuminated, with optional lamp|
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.
SN series uses two separate schemas; the reason for this split is not known.
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 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.
|Catalogue listing||Action||Mount||Lamp||Force||Sensor||Circuit function||Plunger style||NSN||Notes|
|Ⓑ||Momentary||Snap-in||Not supplied||SD-10023||Sink pulse|
|11SN2A1||Alternate action||Snap-in||Not supplied||SW-11920|
|11SN2C1||Alternate action||Snap-in||Not supplied||SW-11921||7025-01-359-9992|
|11SN3D1||Indicator (sprung)||Snap-in||Not supplied||—||—|
|101SN11||PCB||Sloped||5930-01-035-0807||Black plunger; eBay|
|101SN12||PCB||Stepped||Black plunger; eBay (7449)|
|101SN25||PCB||Black plunger; eBay (7449)|
|201SN1A1||Momentary||PCB||Not supplied||Sink level||5930-01-013-3788|
|201SN1B1||Momentary||PCB||Not supplied||SD-10023||Sink pulse||5930-01-025-9323|
|Ⓓ||Momentary||PCB||Not supplied||Sink pulse|
|Ⓑ||Momentary||PCB||Not supplied||Source level|
|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|
|Ⓑ||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]|
|Ⓒ||Alternate||PCB||Not supplied||Sink level|
|Ⓒ||Alternate||PCB||Not supplied||Source level|
At present there is no “M” chart for 101SN.
Honeywell have kindly provided 201SN Charts 1 (M) and 2 (A), which are freely available to all. 201SN Chart 2 (A) is an engineering chart and confidential details are redacted. Additional charts will be posted at a later date, once they are suitably redacted.
- Micro Switch 201SN Series Chart 1, created 1995-09-11, last revised 1999-04-14
- Micro Switch 201SN Series Chart 2 (A), created 1995-09-11, last revised 1996-08
- SN Series, the keyboard version of this switch