I was browsing for push switches on Element14 and due to the vast amount of choices, I wanted to narrow down my search. However I stumbled across the filter category "Switch Operation" and was confused as to the following terminology:
X-X
X-None-X
X-On-X
Where X can be either "On", "Off", "(On)", "(Off)".
Currently, I know the brackets mean momentary which I assume is the state when the button has to be held or pushed by the user. I also know that a SPST with switch operation of On-(Off) is a NO pushbutton and Off-(On) is NC pushbutton, but the existence of other possibilities just confuse me. What do they mean?
There seem to also be filters that seem to be weasel words. So there's "latching" and "Push-On Push-Off" along with "Push-Pull" and "Pull-To-Cheat". Are my assumptions correct?
I even tried to look in the datasheets but they don't really define much, like what is On-(On) vs On-On.
Best Answer
A X-X switch has two possible (stable, for a non-momentary switch) contact positions, or a maximum of two throws if you will. An X-X-X switch has three possible contact positions, or a maximum of three throws, although many of them are double throw switches where the third (center) position is an OFF position.
A "latching" switch is the same as "push-on push-off" or "push-pull" -- all of these mean that the switch does not have any momentary positions in it, although the position designator ("On-On" or whathaveyou) is the ultimate guide to this. The manufacturer's datasheet should provide a schematic symbol or some other sort of usage documentation for the switch, as well.