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Old 11-11-2008 | 05:49 AM
  #70  
Bigboat
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From: Alkmaar, NETHERLANDS
Default RE: $25 CDI


ORIGINAL: captinjohn


ORIGINAL: Bigboat

Most common hallsensors are uni-polaire.
A uni-polaire needs only a south form the (neodymium) magnet to switch on / off
A bi-polaire sensor needs a south to switch on and a north to switch off.

http://parts.digikey.co.uk/1/1/87891...37-wl-7-b.html
Big Boat...to put it simple, if our pic-up sensors have only one magnet ....are they neodymium? Like-wise if they are bi-polar...you need 2 magnets in hub? I got a feeling you could make the answers a lot more imformitive to us. Capt,n
Most magnets they use for CDI are neodymium becourse they are very strong and small becourse they are strong.
If your using a biopolaire, you don't need twoo magnets, but you have to position the magnet the hallsensor can read both sites.......norht and south.
If your using a *horsshoe* magnet, you don't have a problem.
One leg will be south and the other will be norht.
A long (straight) magnet gives your trouble, becourse the norht and south feeld are on top of the magnets in a straight line.