Line6 dual function switches: are they mechanical switches or digital logic?

[iaresee]

This curiosity arose from a post in another forum. The ability to do tap tempo and effect on/off switching on some of the Line6 products is neat. Is it a mechanical switch they use that has two modes of operation depending on the amount of travel (momentary and switched)? Or is it a momentary switch tied to digital logic that decides if the switch is being tapped or stomped on?

[frequencycentral]

The other guitarist in my band has a Line 6 Pod XT Live, sometimes I use it to tune up (about all its good for IMO!), I would guess its momentary and logic.

Rant: He has a lovely Crate 100 watt valve head and 4x12, he sets the volume real low (like '1') and uses the Line 6 for everything else. What's the point?

[Mark Hammer]

Since I have had to repair one of my Tone Core pedals that would not switch at all, I can offer the following.  When the treadle is depressed, there are two plungers that move down.  The one which makes first contact depresses a fairly soft touch momentary switch that is installed juuuuuuuuuust a little bit higher than the second switch.  The second switch, meanwhile has a convex spring steel leaf situated above it which does several things.  First, it provides some resistance such that you really have to push to bend it in the other direction (from convex to concave), making it easier to tactually differentiate the two actions: tap tempo and bypass.  Second, the sort of "dome" the leaf makes over the second micropswitch protects that switch unless sufficient pressure is applied; i.e., no accidental pushes.  Third, the sudden snap of the spring leaf provides an audible and tactile click that people seem to like about stompswitches.

Oddly enough, the one I had to repair had accidentally acquired two spring-leafs that had accidentally gotten stuck together (they ARE rather thin) in the bin and been installed as if they were one.  Naturally, this little hunk of "spring-steel plywood" was a tad on the stiff side and I couldn't get it to snap from convex to concave no matter how hard I pushed with my foot.

Having said all of that, despite the two switches, when your foot finally DOES actuate the bypass one, it is also pressing down on the tap-tempo switch too, so I imagine there is some logic in there as well such that the sustained press on the higher-softer tap tempo microswitch is not misinterpreted by the pedal as a request for a VERY slow tempo.

[iaresee]

Thanks Mark. That was exactly what I was after. I was wondering specifically how they handled not setting a tempo when someone was rapidly turning the effect on and off. If it's two momentary switches that's not so hard to do with a bit of logic. Elegant in its approach but difficult to implement correctly.