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Subject: 
Re: touch sensors aren't just switches (was Re: ideas for a RIS 2.0
Newsgroups: 
lugnet.robotics
Date: 
Wed, 25 Aug 1999 21:47:12 GMT
Viewed: 
974 times
  
In lugnet.robotics, Ralph Hempel writes:
I think it also removes the need to eliminate "keybounce", the annoying
thing that happens with real switches due to dirt on the contact
surfaces and tiny arcs (sparks) just before initial contact.

The actual source of bounce is NOT the arc just before contact. It
actually is the bouncing of the contact due to the action of the spring
in the contact!

That obviously depends on what type of physical design is used for the switch.

Some switches are not capable of bouncing the way you describe because there is
no impact or acceleration during contact (example: slide switches that move
leaf springs across traces on a PCB -- many linear and rotary
multipole-multithrow switches are built that way)

And of course, some switches do. So, if you wish to be complete, you should add
"actual physical vibration" to the other causes ("dirt" and "arcing") that I
mentioned.

- Robert Munafo                           http://www.mrob.com/
  LEGO: TC+++(8480) SW++ #+ S-- LS++ Hsp M+ A@ LM++ YB64m IC13



Message has 1 Reply:
  Re: touch sensors aren't just switches (was Re: ideas for a RIS 2.0
 
Any motion between two hard surfaces, including sliding metal on metal (often called contact wiping), creates intermittent contact that has to be "debounced". The only switches that don't bounce are mercury-wetted contacts, such as one used to find (...) (25 years ago, 25-Aug-99, to lugnet.robotics)

Message is in Reply To:
  RE: touch sensors aren't just switches (was Re: ideas for a RIS 2.0
 
(...) The actual source of bounce is NOT the arc just before contact. It actually is the bouncing of the contact due to the action of the spring in the contact! Well, if you were switching a really high voltage through a small switch, you would get (...) (25 years ago, 25-Aug-99, to lugnet.robotics)

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