Hi All,

Probably ot but I know there is a pretty broad range of skills on here
and I really wouldn't know where else to ask ..?

I was talking to my 30+ year experience bike mechanic mate today and
he posed me with an electrical puzzler.

He had the stator from a small modern scooter on the bench and was
trying to work out the function of a pair of the coils.

There were 3 that fed the regulator / rectifier .. (so far so good)

There was one that fed the CDI unit ..(ok again)

A 'trigger' coil / pickup for timing ... (std so far)

... and 2 coils joined in series that (apparently) weren't connected to
anything at the stator end but directly connected to the un-switched
+ve battery terminal at the other?

Weird?

Any thoughts please?

All the best ..

T i m

T i m wrote:
Hi All,

Probably ot but I know there is a pretty broad range of skills on here
and I really wouldn't know where else to ask ..?

I was talking to my 30+ year experience bike mechanic mate today and
he posed me with an electrical puzzler.

He had the stator from a small modern scooter on the bench and was
trying to work out the function of a pair of the coils.

There were 3 that fed the regulator / rectifier .. (so far so good)

There was one that fed the CDI unit ..(ok again)

A 'trigger' coil / pickup for timing ... (std so far)

.. and 2 coils joined in series that (apparently) weren't connected to
anything at the stator end but directly connected to the un-switched
+ve battery terminal at the other?

Weird?

Any thoughts please?

All the best ..

T i m
I know very little about vehicle electrics (which will shortly become
very apparent). Could it be anything to do with electrical suppression
to prevent interference?
PJ

On Thu, 10 Mar 2005 01:29:56 +0000, PJ wrote:


I know very little about vehicle electrics (which will shortly become
very apparent).

At the moment it could be to do with *anything* so thanks for your
input ;-)

Could it be anything to do with electrical suppression
to prevent interference?

Possible ...

T i m

T i m wrote:

Hi All,

Probably ot but I know there is a pretty broad range of skills on here
and I really wouldn't know where else to ask ..?

I was talking to my 30+ year experience bike mechanic mate today and
he posed me with an electrical puzzler.

He had the stator from a small modern scooter on the bench and was
trying to work out the function of a pair of the coils.

There were 3 that fed the regulator / rectifier .. (so far so good)

There was one that fed the CDI unit ..(ok again)

A 'trigger' coil / pickup for timing ... (std so far)

.. and 2 coils joined in series that (apparently) weren't connected to
anything at the stator end but directly connected to the un-switched
+ve battery terminal at the other?


Coils have two ends. What was the OTHER end connected to,.

Weird?

Any thoughts please?

All the best ..

T i m

In article , "The Natural
Philosopher" says...
T i m wrote:

Hi All,

Probably ot but I know there is a pretty broad range of skills on here
and I really wouldn't know where else to ask ..?

I was talking to my 30+ year experience bike mechanic mate today and
he posed me with an electrical puzzler.

He had the stator from a small modern scooter on the bench and was
trying to work out the function of a pair of the coils.

There were 3 that fed the regulator / rectifier .. (so far so good)

There was one that fed the CDI unit ..(ok again)

A 'trigger' coil / pickup for timing ... (std so far)

.. and 2 coils joined in series that (apparently) weren't connected to
anything at the stator end but directly connected to the un-switched
+ve battery terminal at the other?


Coils have two ends. What was the OTHER end connected to,.

Earth?

On Thu, 10 Mar 2005 02:35:08 -0000, Rob Morley
wrote:


.. and 2 coils joined in series that (apparently) weren't connected to
anything at the stator end but directly connected to the un-switched
+ve battery terminal at the other?


Coils have two ends. What was the OTHER end connected to,.

Earth?

No, that was the point .. the stator end of the cct in question was
connected to ... nothing? Well, it was connected to a solder tag on
the bobbin but that in turn wasn't connected to anything?

I actually followed the wiring myself ... bike connector .. wire down
to stator ... onto coil one .. through coil on to coil two .. through
coil two and terminated on tag on the top of the bobbin .. stop / end
/ finish?

He (and an auto electrician) has even put his DMM over the whole thing
and checked for any hidden wiring but nothing. Connect one meter lead
to the bike connector end of the cct and you can follow the (~0 ohms)
to the first coil and to the end of the second but not to anywhere
else? Maybe it *should* be connected to ground and something has
melted away but if so why would the other end be connected directly to
the +ve battery terminal (and this isn't a 'mod', it's all part of the
loom and the same on many bikes)?

Maybe they are there for use on a different model but if that was the
case why:

1) Is there a wire (loom) connected to it at the stator end?

2) Is the other end of this single ended cct connected to the (perm,
not switched) +Ve battery terminal?

Trust me, I've actually held this assembly in my hand and visually
traced all the wires / coils back and can account for every part ...
except for this bit?

scratches head

All the best ..

T i m

T i m wrote:

On Thu, 10 Mar 2005 02:35:08 -0000, Rob Morley
wrote:



.. and 2 coils joined in series that (apparently) weren't connected to
anything at the stator end but directly connected to the un-switched
+ve battery terminal at the other?


Coils have two ends. What was the OTHER end connected to,.


Earth?


No, that was the point .. the stator end of the cct in question was
connected to ... nothing? Well, it was connected to a solder tag on
the bobbin but that in turn wasn't connected to anything?

I actually followed the wiring myself ... bike connector .. wire down
to stator ... onto coil one .. through coil on to coil two .. through
coil two and terminated on tag on the top of the bobbin .. stop / end
/ finish?

He (and an auto electrician) has even put his DMM over the whole thing
and checked for any hidden wiring but nothing. Connect one meter lead
to the bike connector end of the cct and you can follow the (~0 ohms)
to the first coil and to the end of the second but not to anywhere
else? Maybe it *should* be connected to ground and something has
melted away but if so why would the other end be connected directly to
the +ve battery terminal (and this isn't a 'mod', it's all part of the
loom and the same on many bikes)?

Maybe they are there for use on a different model but if that was the
case why:

1) Is there a wire (loom) connected to it at the stator end?

2) Is the other end of this single ended cct connected to the (perm,
not switched) +Ve battery terminal?

Trust me, I've actually held this assembly in my hand and visually
traced all the wires / coils back and can account for every part ...
except for this bit?

scratches head

All the best ..

T i m



Only time I have seen a coil with only one end connected is when its
used as a quick and dirty way to provide an electrostatic shield -
typically in a transformer where you wind a layer between primary and
sceondary and earth it, to reduce capacitative coupling between tow
windings.

On Thu, 10 Mar 2005 13:12:15 +0000, The Natural Philosopher
wrote:


Only time I have seen a coil with only one end connected is when its
used as a quick and dirty way to provide an electrostatic shield -
typically in a transformer where you wind a layer between primary and
sceondary and earth it, to reduce capacitative coupling between tow
windings.

I suppose if you earthed both ends you would induce large currents in
that 'screen' coil and partially defeat the function of the Xformer?

I can't see how this might apply to the stator though (much though I
would like it to g) because of the layout ..

Going round the stator you have coils 1,2,3 charging, 4,5 'unknown', 6
CDI feed.

There is a trigger coil that is on a short length of wire tied into
the stator (but not electrically connected to the stator .. just
passing through) and that just goes up to the ignition / amp / reg
unit.

So, 3 'modules ..

Rotor / stator assy . producing charging current, cdi current and
ignition timing.

CDI unit, probably powered from the LT supply and 'charged' by the
single coil in the stator. (moulded coil looking thing with HT lead
sticking out ..)

Ignition / reg module, also powered by the battery (ignition feed) and
with the ignition trigger input but also rectifying / regulating the
alternator output to the battery (ally heatsink moulded thing)?

All the best ..

T i m

On Thu, 10 Mar 2005 01:56:11 +0000, The Natural Philosopher
wrote:


.. and 2 coils joined in series that (apparently) weren't connected to
anything at the stator end but directly connected to the un-switched
+ve battery terminal at the other?


Coils have two ends. What was the OTHER end connected to,.

Erm "and 2 coils joined in series that (apparently) weren't connected
to anything at the stator end" ?

I know what you are saying but that was the whole point of my
question. Both my mechanic mate and the auto-electrician that fixes
stuff for them were also baffled?

And not all coils are connected to something solid at both ends .. the
secondary on a HT coil is *connected* to a gap ;-)

All the best ..

T i m

It was somewhere outside Barstow when T i m wrote:

.. and 2 coils joined in series that (apparently) weren't connected to
anything at the stator end but directly connected to the un-switched
+ve battery terminal at the other?

Obviously they were connected to something, you just haven't found it
yet.

Could they generate field in the rotor, to power the alternator but
avoiding sliprings ?

On Thu, 10 Mar 2005 12:44:25 +0000, Andy Dingley
wrote:

It was somewhere outside Barstow when T i m wrote:

.. and 2 coils joined in series that (apparently) weren't connected to
anything at the stator end but directly connected to the un-switched
+ve battery terminal at the other?

Obviously they were connected to something, you just haven't found it
yet.

Em .. not sure how 'obvious' Andy? My first thought were that these
were 'spare' to this model but if that was the case wouldn't they just
leave them o/c? If that might cause other problems why would you
connect one end to +ve battery (not gnd) ?

Could they generate field in the rotor, to power the alternator but
avoiding sliprings ?

Well that was the sort of potential answer I was looking for .. maybe
something that wasn't 'traditional' or 'obvious' .. ?

I know how stuff changes, things that weren't possible / typical to
start with (dimmable low voltage lights etc) but someone comes up with
a clever solution and away we go ?

Ok, in this case *I* didn't actually take the stator out myself nor
did I measure it but my mechanic mate has been fixing bikes / scooters
since the good old days and has been known to rewind an ignition coil
or two in his time so isn't easily 'fooled' by much.

So, this particular scooter isn't running, the o/p from the coil that
feeds the CDI unit is low and they have changed most things except for
this stator. It was whist checking the stator closer he found this
weird configuration (with the open ended coil pair) and wondered if
this was playing some part in the 'fault'?

In theory it's not *needed* (there are 3 charging coils, 1 CDI ignitor
coil and a timing trigger coil / pickup) but if these extra pair were
n/a you would have though they would have dealt with them differently
(ie, not wiring them into the loom or connecting them to the perm +ve
supply)?

And that last bit adds to the mystery .. if they *were* connected to
something it would have to be either something like a capacitor (or it
would discharge the battery unles the -ve battery supply was chopped
with the ignition via relay or summat) ?

The cct diagram shows all the wires going to the places mentioned
above (regulator / rectifier, CDI, battery etc) but not a detailed
layout for the stator itself (just a generator symbol).

All the best ..

T i m

They create a permanent magnetic field in the stator when they are
energised.

On 10 Mar 2005 05:08:35 -0800, "kmillar" wrote:

They create a permanent magnetic field in the stator when they are
energised.

Wouldn't there have to be connected to something (other than the +12V)
for that to happen though? (just asking?)

T i m

kmillar wrote:

They create a permanent magnetic field in the stator when they are
energised.


Yes. I was thinking that too. Is it possible that the rotor is not
actually permanent magnets? In which case you need to run that coil to
ground to keep the motor running, and dicoonnect it to stop the engine.

That way the rotor can be simply some lumps of rotating iron. I think.

On Thu, 10 Mar 2005 13:14:46 +0000, The Natural Philosopher
wrote:

kmillar wrote:

They create a permanent magnetic field in the stator when they are
energised.


Yes. I was thinking that too. Is it possible that the rotor is not
actually permanent magnets? In which case you need to run that coil to
ground to keep the motor running, and dicoonnect it to stop the engine.

That way the rotor can be simply some lumps of rotating iron. I think.

More good thoughts .. I didn't actually get to see the rotor but I
can pop in and look.

To get the above the ('currently' .. excuse the pun) 'unterminated'
end of the coil pair would have to be switched to earth to generate
the stator field (that could be done by a 'kill switch' or whatever
but there were no signs of such a wire? Also if you forgot to use the
kill switch it would just flatten the battery with the existing setup
(end of the 'unknown use' coils is connected to +ve)?

All the best ..

T i m

T i m wrote:

On Thu, 10 Mar 2005 13:14:46 +0000, The Natural Philosopher
wrote:


kmillar wrote:


They create a permanent magnetic field in the stator when they are
energised.


Yes. I was thinking that too. Is it possible that the rotor is not
actually permanent magnets? In which case you need to run that coil to
ground to keep the motor running, and dicoonnect it to stop the engine.

That way the rotor can be simply some lumps of rotating iron. I think.


More good thoughts .. I didn't actually get to see the rotor but I
can pop in and look.

To get the above the ('currently' .. excuse the pun) 'unterminated'
end of the coil pair would have to be switched to earth to generate
the stator field (that could be done by a 'kill switch' or whatever
but there were no signs of such a wire? Also if you forgot to use the
kill switch it would just flatten the battery with the existing setup
(end of the 'unknown use' coils is connected to +ve)?

All the best ..


Yes, and presumably the engine would run till it had no more fuel.

If it is an 'energised' stator, I'd say that is the logical place to put
and ignition switch.

Its often done that way - in the 'earth ' circut, becasue you can then
simply have a bit of wire being earthed to chassis to make the whole
ignition stuff work, rather than having to carry in a live wire and out
again. Well it used to be on older simpler cars anyway.


T i m

In article ,
T i m wrote:
To get the above the ('currently' .. excuse the pun) 'unterminated'
end of the coil pair would have to be switched to earth to generate
the stator field (that could be done by a 'kill switch' or whatever
but there were no signs of such a wire? Also if you forgot to use the
kill switch it would just flatten the battery with the existing setup
(end of the 'unknown use' coils is connected to +ve)?

What's the resistance of the coils?

--
*According to my calculations, the problem doesn't exist.

Dave Plowman London SW
To e-mail, change noise into sound.

On Thu, 10 Mar 2005 15:23:48 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
T i m wrote:
To get the above the ('currently' .. excuse the pun) 'unterminated'
end of the coil pair would have to be switched to earth to generate
the stator field (that could be done by a 'kill switch' or whatever
but there were no signs of such a wire? Also if you forgot to use the
kill switch it would just flatten the battery with the existing setup
(end of the 'unknown use' coils is connected to +ve)?

What's the resistance of the coils?

I'd have to guess pretty low Dave as they look to be about .75mm 1mm
dia shelac'd copper wire and probably no more than a couple of hundred
turns around a 20mm (ave) dia bobbin (x 2 in series)?

So Pi * d ~= 25m of (say) 1mm dia copper wire for both (if my maths
is ok?) .. what's the resistance in that?

I'm going past the shop in a mo so if the stator is still out I'll put
his DMM across it and let you know ..

Probably too low a resistance to go straight across 12V without
cooking?

All the best ..

T i m

On Thu, 10 Mar 2005 15:23:48 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
T i m wrote:
To get the above the ('currently' .. excuse the pun) 'unterminated'
end of the coil pair would have to be switched to earth to generate
the stator field (that could be done by a 'kill switch' or whatever
but there were no signs of such a wire? Also if you forgot to use the
kill switch it would just flatten the battery with the existing setup
(end of the 'unknown use' coils is connected to +ve)?

What's the resistance of the coils?

I measured them todat and they were about .7 of an ohm?

They 'cured' the fault (the bike wouldn't run) by changing the entire
stator for a second hand one.

The only difference between the good and bad setups was the coil that
fed the CDI unit was a higher resistance.

All the best ..

T i m

In article om,
"kmillar" says...
They create a permanent magnetic field in the stator when they are
energised.

Except that as they're not connected no current would flow, and if
they were connected the battery would drain.

On Thu, 10 Mar 2005 16:18:49 -0000, Rob Morley
wrote:

In article om,
"kmillar" says...
They create a permanent magnetic field in the stator when they are
energised.

Except that as they're not connected no current would flow, and if
they were connected the battery would drain.

Maybe they just don't do anything ... (or don't do anything on this
model?)

Maybe they happen to be connected to +Ve ... because that's how they
would be wired if they were on another system (that connects the other
end to summat?)

I'd like to think they were there for a reason though .. (who would
bother to add coils if they didn't have to .. saving money etc ..
unless it's cheaper to stock a 'unversal' part ..?)

All the best ..

T i m

In article , "T i m"
says...
On Thu, 10 Mar 2005 16:18:49 -0000, Rob Morley
wrote:

In article om,
"kmillar" says...
They create a permanent magnetic field in the stator when they are
energised.

Except that as they're not connected no current would flow, and if
they were connected the battery would drain.

Maybe they just don't do anything ... (or don't do anything on this
model?)

Maybe they happen to be connected to +Ve ... because that's how they
would be wired if they were on another system (that connects the other
end to summat?)

I'd like to think they were there for a reason though .. (who would
bother to add coils if they didn't have to .. saving money etc ..
unless it's cheaper to stock a 'unversal' part ..?)

Maybe it's a high-voltage (hence two coils in series) feed for the
coil on a kick-start model, and this one is electric start only?

On Thu, 10 Mar 2005 18:01:22 -0000, Rob Morley
wrote:


I'd like to think they were there for a reason though .. (who would
bother to add coils if they didn't have to .. saving money etc ..
unless it's cheaper to stock a 'unversal' part ..?)

Maybe it's a high-voltage (hence two coils in series) feed for the
coil on a kick-start model, and this one is electric start only?

I like the thinking but if you had seen them they look more like
charging / current than voltage coils (if you know what I mean)?

I'll have to find out more about the actual model (I did pop by this
arvo but they close Thursday afternoons .. how quaint) ;-)

I'll look in again ..

Cheers ..

T i m