Technical Question

[KERABO]

Just so I can understand these better can someone answer this question.

Whats the Difference between a 6 pole PAS disc turning fast and a 12 pole turning slow.

It matters or it did on my project, but how does it know If you have the wrong count of magnets?
Is there some sort of pulse to say it’s done a complete turn or is a magnet reversed?
it seems to know if your turning backwards as well.

Thanks

 

[thelarkbox]

not a lot, the speed or frequency of pulses generated by a pas sensor are not important, afaik the controller smarts dont look for anything beyond a correct pulse pattern, as to not be falsely activated by an errant magnetic field -you wouldnt like your bike to take off at a red light because a passing learner lost a magnetic L plate that fluttered by your sensor.. (V unlikely i know..)..

Pages 25-26 of the linked to ktlcd10 manual give examples of forward and reverse pulse patterns, (Left/right side sensor) depending on the hall sensors employed they may trigger on the detection of a magnetic field or on the switching of a magnetic field so a n,s,n,s,n,s sequence of magnets can generate the signals..

 

[eas2lv]

One difference is that, at least on some controllers, the start threshold is set to a certain number of pulses -- say 6 pulses which in case of 12 magnet disc is 1/2 rotation, but 6 magnet disc would take a full rotation of the crank. That is, how quickly the motor engages when you start pedalling depends on the number of magnets and setting programmed into the controller.
asfaik, all magnets are aligned with the same polarity, the sensor has a pair of spatially separated Hall sensors which generates voltage signals when a magnet passes by them. The difference signal of the two Hall voltages is used electronically to generate the pulses. Some generates pulses in both rotational directions with reversed phases, some only for one direction. In either case, dual Hall is required to detect direction. Incorrect magnet polarity or sensor orientation would make the controller respond to backward pedalling instead of forward though.

 

[KERABO]

One difference is that, at least on some controllers, the start threshold is set to a certain number of pulses -- say 6 pulses which in case of 12 magnet disc is 1/2 rotation, but 6 magnet disc would take a full rotation of the crank. That is, how quickly the motor engages when you start pedalling depends on the number of magnets and setting programmed into the controller.
asfaik, all magnets are aligned with the same polarity, the sensor has a pair of spatially separated Hall sensors which generates voltage signals when a magnet passes by them. The difference signal of the two Hall voltages is used electronically to generate the pulses. Some generates pulses in both rotational directions with reversed phases, some only for one direction. In either case, dual Hall is required to detect direction. Incorrect magnet polarity or sensor orientation would make the controller respond to backward pedalling instead of forward though.

Thank you
learning slowly

 

[KERABO]

not a lot, the speed or frequency of pulses generated by a pas sensor are not important, afaik the controller smarts dont look for anything beyond a correct pulse pattern, as to not be falsely activated by an errant magnetic field -you wouldnt like your bike to take off at a red light because a passing learner lost a magnetic L plate that fluttered by your sensor.. (V unlikely i know..)..

Pages 25-26 of the linked to ktlcd10 manual give examples of forward and reverse pulse patterns, (Left/right side sensor) depending on the hall sensors employed they may trigger on the detection of a magnetic field or on the switching of a magnetic field so a n,s,n,s,n,s sequence of magnets can generate the signals..

Thank you

 

[saneagle]

Just so I can understand these better can someone answer this question.

Whats the Difference between a 6 pole PAS disc turning fast and a 12 pole turning slow.

It matters or it did on my project, but how does it know If you have the wrong count of magnets?
Is there some sort of pulse to say it’s done a complete turn or is a magnet reversed?
it seems to know if your turning backwards as well.

Thanks

Theoretically, no difference, but if you want to choose a sensor, avoid 12 magnet ones unless you know what you're doing. Just about every time we get a question on this forum that goes, "I just installed a new kit on my bike and the PAS doesn't work", it's a 12 magnet one.

In practical terms you wouldn't be able to see any difference in performance of the bike with different numbers of magnets. Any delay is from the controller that waits before it does anything, even though it can see the pedal sensor pulsing. Different controllers wait for different times, nothing to do with the pedal sensor itself.

 

[KERABO]

Theoretically, no difference, but if you want to choose a sensor, avoid 12 magnet ones unless you know what you're doing. Just about every time we get a question on this forum that goes, "I just installed a new kit on my bike and the PAS doesn't work", it's a 12 magnet one.

In practical terms you wouldn't be able to see any difference in performance of the bike with different numbers of magnets. Any delay is from the controller that waits before it does anything, even though it can see the pedal sensor pulsing. Different controllers wait for different times, nothing to do with the pedal sensor itself.

Thank you

 

[Nealh]

If one wants a system that has fast PAS pick up with little delay then opt for a KT controller , KT also has instant stop with no noticable run on from PAS.

Take it from those of us that use them all the time from many years of use and experience , for the relative cheap cost of a no OEM system (£75 - £100) there is nothing else out there to beat a KT .