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Does a hall sensor need debouncing with arduino? Answered

Hi, I am trying to measure the time it takes for a wheel to rotate using a hall sensor that was pulled out of a old computer fan. Does this sensor need any debounceing to give accurate readings?

http://www.alldatasheet.com/datasheet-pdf/pdf/178883/ANACHIP/AH284.html

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user
icengBest Answer (author)2013-05-28

Bouncing occurs in most mechanical switches because electrical contacts
have mass that strikes another mass and bounces away like a ball.

Some switches use sealed mercury on the contacts to absorb the
bounce separation motion with overlapping electrical contact through
the liquid mercury.
Similarly the mercury snaps away when opening the contact.

Slide switches still bounce on first mass contact.

There are no striking mass parts on a magnetic tachometer to cause 
a micro electrical interruption.

Additionally the hall sensor has a hysteresis to avoid minor
flux variations.

Finally the hall sensor cannot react as fast as a bouncing mechanical switch. It is limited to no more then 1/(3*10-6) cycles

A

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user
verence (author)2013-05-28

Depends on the hall sensor. Analogue ones will give you an analogue signal that relates to strength and direction of the magnetic field. They may need some kind of averaging. The one you linked seems to be digital and has an internal debouncing by a hysteresis. See page 4 of the data sheet you linked.

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steveastrouk (author)2013-05-28

Probably not. Most Hall sensors have hysteresis, which means they don't bounce. That hysteresis is shown in the datasheet.

Steve

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