Name for type of toggle sw. that is Mom. Off On?

Dave Boland wrote in news:RBywe.64041$ snipped-for-privacy@twister.nyroc.rr.com:

Do you mean "normally open momentary" where "off" means the switch is open an thus passes no current? I would be surprised if

Sometimes the momentary action is denoted on data sheets with th parenthesis e.g. on-off-(on)

This message was sent using the comp.arch.embedded web interface o

Dave Boland wrote in news:RBywe.64041 $ snipped-for-privacy@twister.nyroc.rr.com:

In major electronics catalogs they are usually designated as:

ON-OFF-(ON)

The parinthesies indicates momentary.

But sometimes:

ON-OFF-MOM.

I just went though search for a ON-NONE-(ON), and got a ON-OFF-(ON) by mistake. Typed in the wrong part number from Mouser. So, I know they have them.

Digikey has them also. ALCO, C&K and others

Another odd duck to watch out for is on-on-on. It's a spdt, but in the middle position, the arm is connected to BOTH sides. Tough to figure out what's wroing with your creation if you install one of these by mistake!

Sounds like the toggle switch equivalent to the old "shorting" rotary switch, where the next contact makes before the current one breaks.

While we are on the subject, anyone know a source for momentary contact pushbutton switches. I want one that makes and breaks in one press. [I.e. press and it makes and breaks the contact, release does nothing (except re-arm it for the next press). Years ago I took one apart - basically it's just a little roller under a slider. Goes down one path, and back up the other. One path it makes contact, the other it doesn't.

Can't seem to find one in the catalogs now. Just need a modest sized one that will handle an amp or two. [If I can't find it, I'm going to have to cobble some circuitry together, in a tight space in the housing.] tnx, jmk

I think it's not exactly shorting, but the two sections have different detent points:

o o o o o o | | | o o o o o o | | | o o o o o o

Actually, it sounds like something's broken. How long of a pulse are you looking for?

Good Luck! Rich

You are right, that's different from what I thought was being described.

One man's broken is another man's specification requirement.

These things are mechanical and the pulse length is usually pretty variable... around 100 ms or so. Unfortunately, my ASCII art isn't as good as yours, so I hesitate to even try to draw one. They used to be fairly common, back when "control logic" meant stepper relays and the like. Now I guess it's so much easier to do everything with electronics rather than electromechanical, that pulsing a relay mechanically just isn't much of a market.

jmk