Scooterotica

^... I understand this for the connected lighting coils but have noted that isolated coils on standard 6V stators will follow an alternating pattern too. Should the polarity follow an alternating pattern regardless of whether the coils are connected/wired together or are merely next to each other on the stator base? I ask this as I have original 6V stator that have replacement LT coils fitted soldered joints towards stator centre, others with soldered joints to top/front... yet both work, regardless of adjacent coil polarity.

I home that makes sense?

Adam

firekdp wrote:Coaster, the coils are alternately wound because, at any one time there will be an opposite pole affecting them. A north magnetic pole will will generate an opposite polarity to a south pole. If the adjacent coils were wound the same way it would be like connecting batteries with the positives together, ie no current would flow. As you're winding lighting coils it doesn't matter which direction you wind them, as long as they alternate.

Thanks...logical when you think about it

Adam_Winstone wrote:but have noted that isolated coils on standard 6V stators will follow an alternating pattern too. Should the polarity follow an alternating pattern regardless of whether the coils are connected/wired together or are merely next to each other on the stator base?

Adam

If its a separate coil working independently from any other coil then it will make no difference which way it's wired as it would produce ac current and it wouldn't effect the phasing of unconnected lighting coils.

I once inadvertently wired a standard Italian stator to 12 volt dc but with one lighting coil wound out of phase for bedlam scooters, the bobbin was intended for another conversion but it went on by mistake the way it was wired no power to the lights would come out of the stator at all, but to look at it you would think it was right. it wasn't... But it didn't effect the ignition coil adjacent to it.

As for wiring alternating coils, it is done that way on Lammys, But...

(as I've done this in the past to prevent a scooter shop copying one of my earlier conversions when making an old Motopat electronic rectifier work from a ducati electronic stator, otherwise the scooter would have needed to be rewired, this was the the motoplat type that Dave Webster used to fit)

So what im saying is that All four lighting Coils can all be wound in the same direction, current will be produced but the inter-connecting wires between the coils would have to be connected so that the out of phase wound coils are connected in the correct way to put them back into phase.

The Pick-up has two internal coils these are wound to face opposing magnets, one north and one south, which are connected to give the correct phasing but only when opposing magnets pass, all other pulses from the other magnets are cancelled out because they become out of phase as only one single magnet is covering both coils of the pick up at any one time, that is until the cross over magnets pass over causing current to flow at about 1.5 volts

The ignition coil would produce ac in a full sine wave if it was allowed to, but it doesn't as it fires on only one magnetic pole of the flywheel, that is the magnet that passes the coil as the pick-up is triggered, so only one half of the ac sine wave is used to fire the spark, which I think from memory is positive earth, but it's a long time since I've done any indepth electricals on an electronic stator so I could be wrong.

But it is only triggering on one half of the ac sine wave, so connecting the LT coil in the reverse to original would alter the phasing of the coil by reversing the sine wave produced at ignition point making the spark produced opposite polarity to original.

An ac coil is used as its much easier to produce the high voltage that's needed to produce a spark it's not trying to fire an ac spark but just trying to fire a high energy polarised spark when it's actually needed.

But I might be wrong...

Mark.

Fantastic stuff J1MS, as my interest is with 12 volt electronic stators I will start another thread rather than hijack this one

^... yep, Jims is 'the kiddie'!

Thanks for responding to confirm that non-connected coils function in isolation and the polarity of adjacent coils is of no real influence. In light of this, why do you thin that the original 6V stators have the LT coil mounted at 180 degrees to the others?

Another question.... Jem once told me that his original GP200 Electronic loom, on which he bases those that he remakes, has a length of solid core wire fitted in-line with one of the wires/colours, which I seem to remember was either part of the ignition wiring or the battery wiring. Sorry that I can't be more specific but being the clever chap that you are, I was hoping that you might shed some light on this element too?

Adam

Adam_Winstone wrote: why do you thin that the original 6V stators have the LT coil mounted at 180 degrees to the others?

Another question.... Jem once told me that his original GP200 Electronic loom, on which he bases those that he remakes, has a length of solid core wire fitted in-line with one of the wires/colours, which I seem to remember was either part of the ignition wiring or the battery wiring. Sorry that I can't be more specific but being the clever chap that you are, I was hoping that you might shed some light on this element too?

Adam

The original LT coil is mounted backwards onto the laminates of the original stator's and the LT coil is then retained by a fibre washer then a non ferrous retaining plate.

So why is the coil on backwards?
Possibly to put the bare ends of the LT Coil behind the non ferrous (Aluminium) retaining plate... And I think there is a purpose for it being done this way...

The Alloy plate is fitted for One main reason which is to help prevent the LT coil picking up pulses from the adjacent magnets either side of the magnet that is firing the LT coil, the opposite pole's magnetic field from the two magnets either side of the LT coils firing magnet would have a slight effect on the laminate that holds the LT coil which would lessen the power of the pulse from the firing magnet. The alloy plate helps prevent this...
On the later SIL and Vespa stators a copper plate is used, again it's a non ferrous metal which will help shield the magnetism from opposing magnets to the LT Coil...
So it's still being done this way to help isolate the coil from opposite poles, but the coil is now mounted as lighting coils. Perhaps they were Originally being over cautious in trying to cancel out the effects of the other magnets and protect the thin coil wires...

One problem it caused on the original stators was any water retained in the fibre gasket that sat between the alloy plate and the lt coil shorted out the LT coil causing misfires and cutouts, making It less reliable than it should have been, but this only came about as he stators aged and the lacquer they were coated in broke down allowing the water to seep into the gasket...

My educated guess for mounting the LT coil backwards is...

It was done to isolate the free ends of the LT coil behind the alloy plate & help in keeping them insulated behind the fibre washer & it would possibly help prevent unwanted magnetic pulses more efficiently & also protect the thin wire more than if it were mounted away from the alloy plate & fibre packing...

As for the Electronic looms, I have heard of a solid wire in them. But I really couldn't comment as ive never looked properly at an original one...

Don't take this info as gospel as its only my observations.

Mark.

Adam_Winstone wrote:^... I understand this for the connected lighting coils but have noted that isolated coils on standard 6V stators will follow an alternating pattern too. Should the polarity follow an alternating pattern regardless of whether the coils are connected/wired together or are merely next to each other on the stator base?
I home that makes sense?
Adam

I believe all lighting coils (even independant circuits) are wound alternately to keep all power wires in phase. As these circuits share the same return wire, out of phase currents would be opposing each other in the earth wires and therefore current would tend to flow from one coil output to another rather than down the earth wire.
The LT coil orientation though wouldn't IMO make much difference, as whichever way, the CDI will still receive three charging positive pulses before the trigger fires and there will be no change in the polarity of the spark. The crucial part is the polarity and correct connection of the pick up wires onto the CDI.

I have the original LT coil which was replaced and have been told a good one has a resistance of 500 ohms, I've tested mine and it gives a bit over 500 ohms:

Would you put it back on?

I'm going to refit it and wire it correctly and see what happens - what do you think?

Rich

As the LT for an original 6V stator will be the thinner core spec', same as the Vespa + 80s AF stators, there is a good chance that the LT fitted as a replacement is half decent anyway. As such, and especially considering the work to remove and replace the one that's on there, I'd leave it as it is and just unsolder/re-solder the connections correctly, then try it. That way you limit the work first time around and save work if you do all the work only to find that you still don't have a spark!

Adam

:bouncing: I got the power!! :bouncing:

Followed Adams advice and rewired the LT coil, now sparking through the red box.

Thanks for everyone's input.

Richard