How many south poles are there in LGB chuff trigger axle ring magnet

[beavercreek]

Just wondering how many south poles are in the ring magnet found on the trigger axle in LGB sound locos. 1, 2 or 4? (it is the south pole that triggers the hall sensor)

 

[muns]

Now how would you find that out?

 

[beavercreek]

If I had an LGB Uintah/Sumpter magnet and had my old compass to hand, I could do it easily but I don't at present.
Also the Neo magnets that I do have are pretty powerful . Although I have worked out which pole is which on the Neos by testing them with a hall sensor, I fear that even if I did have a LGB axle chuff magnet to test, I could damage the LGB magnet with the neos as they are very powerful compared with the ferrite LGB variety and they have much better magnetic retention whereas the LGB ones can lose there very easily

 

[bobg]

Thinking very hard (it's been a long time since I dealt with this sort of thing); I think what triggers the 'Hall ' is the magnetic fluctuation, rather than the 'pole'. Effectively it generates a minute voltage which is only read as/when it exceeds a pre-set level. So the question is really how many changes are there round the ring, which would be four, for four chuffs, except if the circuit was designed to "double up" or more.



(OUCH!!!!!!!!!)

 

[beavercreek]

I think what triggers the 'Hall ' is the magnetic fluctuation, rather than the 'pole'.
(OUCH!!!!!!!!!)

Hi Bob
well I have a few spec sheets of various forms of hall sensor and they do seem to have polarity features.
Unipolar needs a South to trigger and then a North to stop
Bipolar needs a South to trigger only
Multipolar triggers for both South and North.

I am using the type that Peter Ting at Massoth said was used in the Massoth hall sensor/axle combination...bipolar which is South pole triggered

 

[beavercreek]

This post is also on the other threads about this conversion


I rigged up a tender with out the top with the sumpter/uintahsoundcard, speaker, hall sensor and power coming from the Annie loco (the plugs are already there). I used two magnets 180 degrees apart on the back of one wheel. I had to put two shims between the wheel and journal to keep it central. Made a housing for the hall sensor with wiring and stuck that onto the back of the bogie.
Hung the tender behind an Annie , applied the power and.....
Success.!!
It worked superbly and even without the cover, the improvement on sound as opposed to the original was immense. Also there are the other sounds that come with the LGB sound card like brake squeal, whistle, bell etc. and not forgettingthe back-up capacitors that came with the boards.
So cost-wise ? 35 average for the four cards, £1 for the hall sensor and magnets a new effective sound system emerged for about £30. Of course there was a lot of fiddling to find the correct way of rigging it up..oh and some darned good input from the lads on this forum and also Peter Ting's info from Massoth about the card itself.
Excellent ....now to rig up the other three tenders

 

[bobg]

I think what triggers the 'Hall ' is the magnetic fluctuation, rather than the 'pole'.
(OUCH!!!!!!!!!)

Hi Bob
well I have a few spec sheets of various forms of hall sensor and they do seem to have polarity features.
Unipolar needs a South to trigger and then a North to stop
Bipolar needs a South to trigger only
Multipolar triggers for both South and North.

I am using the type that Peter Ting at Massoth said was used in the Massoth hall sensor/axle combination...bipolar which is South pole triggered

Can't argue with that, as I said, it was a long time ago, and I'm not sure I understood it fully even then. Things soon moved on to magnetic reluctors, which were supposedly more reliable for ingnition systems.