Editing ITT ETL18

{{infobox dswitch
| image name        = ITT ETL18 key switch profile.jpg
| manufacturer      = [[ITT]]
| product code      = 
| switch type       = Tactile
| sense method      = [[Metal contact]]
| switch mount      = [[Plate mount]]
| keycap mount      = Proprietary cruciform
| patents           = [https://www.google.com/patents/US4514609 US4514609 A] (1982)
}}

'''ETL18''' is a [[horizontal spring]] switch, or a series of such switches, from [[ITT]].

==Description==
The name "ETL18" is taken from the branding on the top of the switch. A search for ETL18 at Oxygen Electronics (as of November 2016) returns two results: ITT ETL18 (depicted per other discovered ETL18 switches) and ITT ETL18H1X1GC.<ref name="O2" /> The latter may refer to a specific part in series ETL18, which would make sense as more than one product in the range is likely.

The switch is relatively large: the ridge that sits above the plate is 18 mm square, while the body is 16.3 mm square. Shell height is 13.6 mm, and the top of the mounting plate comes 11.6 mm above the top of the PCB. These non-[[DIN-compliant]] dimensions are curious for a German-made switch patented only a year before widespread adoption of DIN-compliant dimensions in 1983.

The keycap mount is proprietary cruciform; the switches do accept SMK keycaps made for [[SMK J-M0404 series]] switches. Cherry MX keycaps do not fit. The cross arms are the correct width to accept Mitsumi Commodore 64 keycap, but the slot widths within the keycap allow it to tilt on the keystem.

The switch features [[sealed terminals]] (with grey sealant instead of the typical red) and two recesses underneath to allow diodes to be placed below the switch.

===Internals===
The ITT switches are different from other internal spring-based key switches in that the spring is horizontally mounted through the key stem as depicted below. The dual metal contact fins appear to be for a dual pole switch but they connect to single contacts at each end of the switch. The tactile feel is provided by the internal [[Horizontal spring]].

Testing with a multimeter demonstrates that the spring and contact arrangement does not provide [[hysteresis]].

==Variants==
The switch has one known variant.

{| class="wikitable variants-table"
! !! Description
|-
| [[File:ITT ETL18 key switch profile.jpg|175px]] || Standard weight momentary
|}

==Keyfeel==
The horizontal internal spring provides a tactile feel. The switch feels a lot like tactile [[Mitsumi miniature mechanical]], but without that switch's rough feel. It lacks the tactile lead-in of the Mitsumi switches, however, with an immediate tactile peak that could possibly be described as "bouncy". While the Mitsumi switches drape the spring over a central hub, the ITT switches rely solely on a lateral buckling action of the spring to deliver a very smooth [[force curve]].

==Keyboards==
*[[Interact One]] (PCB mount)

==Gallery==
<gallery widths=250 heights=167>
File:ITT_ETL18_key_switch_profile.jpg             | ETL18 keyswitch
File:ITT_ETL18_key_switch_side_1.jpg              | Key switch side
File:ITT_ETL18_key_switch_side_2.jpg              | Key switch alternate side
File:ITT_ETL18_top_popped_off.jpg                 | Top popped off
File:ITT_ETL18_cap_removed.jpg                    | Upper shell removed
File:ITT_ETL18_partially_assembled.jpg            | Partially assembled view
File:ITT_ETL18_partially_assembled_2.jpg          | Alternate partially assembled view
File:ITT_ETL18_horizontal_spring_and_key_stem.jpg | Horizontal spring in keystem
File:ITT_ETL18_spring_key_stem.jpg                | Spring and keystem
File:ITT_ETL18_key_stem_and_spring_separated.jpg  | Keystem and spring separated
File:ITT_ETL18_outer_cap.jpg                      | Upper shell, from above; "Made in W.-Germany" can be seen in small letters
File:ITT_ETL18_inner_cap.jpg                      | Upper shell, from below
File:ITT_ETL18_outer_bottom.jpg                   | Lower shell, from below
File:ITT_ETL18_inner_bottom.jpg                   | Lower shell, from above
</gallery>

==References==
<references>
<ref name="O2">Oxygen Electronics, LLC — [http://www.o2xygen.com/search.aspx?search_part_number=ETL18 Search for Parts] (results for ETL18)</ref>
</references>

[[Category:ITT switches]]
[[Category:Tactile switches]]
[[Category:Horizontal spring switches]]
[[Category:List of all keyboard switches]]