Re: The mechanism behind bouncing...

On Fri, 2 Feb 2007 16:16:44 -0500, "KILOWATT"
<kilowatt"nospam"@softhome.net> wrote:

Hi... thanks for your attention.

I just wish to know the precise reason why for example, a digital counter
may count many pulses on it's clock input when the clock is feed via a non
noise-free source like a mechanical switch. It is because when the contacts
makes/breaks, arcing (i've read somewhere that there can be a possibility of
arcing even at low voltage) occurs, or if it's because of the very rough
surface (microscopically-speaking) of the switch contacts, were the metal
molecules grinds (and possibly flexes) together, during switch activation?
TIA for your reply.

Bouncing means bouncing. When contacts collide, they, well, bounce,
like a ball hitting the floor. Multiple contacts are made and unmade
until it settles down. This is quite visible on an oscilloscope.
Small, low mass contacts have a higher mechanical resonant frequency
so tend to have higher bounce rates and settle faster. Mercury-wetted
contacts don't bounce at all.

There's no significant arcing contribution at low voltages.

Incidentally, for both wet and dry contacts, the initial electrical
connection can have sub-nanosecond risetime.

John



.

Relevant Pages

  • Re: The mechanism behind bouncing...
    ... may count many pulses on it's clock input when the clock is feed via a non ... noise-free source like a mechanical switch. ... arcing (i've read somewhere that there can be a possibility ... So the average distance between the constants is changing ...
    (sci.electronics.basics)
  • Re: The mechanism behind bouncing...
    ... I just wish to know the precise reason why for example, ... may count many pulses on it's clock input when the clock is feed via a non ... noise-free source like a mechanical switch. ... arcing (i've read somewhere that there can be a possibility ...
    (sci.electronics.basics)
  • The mechanism behind bouncing...
    ... may count many pulses on it's clock input when the clock is feed via a non ... noise-free source like a mechanical switch. ... arcing even at low voltage) occurs, or if it's because of the very rough ...
    (sci.electronics.basics)
Loading