Scooterotica

Does the regulator for a 12 volt electronic stator (non battery) boost to 12 volts or does it simply cap the output so you don't go over voltage and blow bulbs. My stator is putting out between 8 and 11 volts depending on the revs but the output side of the regulator is doing just the same. Is the regulator knackered or is it the stator?

It caps it.
It's not certain that the voltage you are measuring from your stator is what you think.
Cheap digital meters (not true rms) use something called form factor correction which is crap when you get significantly away from 50hz.

That said, at low revs it's probably about right.

Blah, blah, i reckon your regulator is duff.

hendy wrote:It caps it.
It's not certain that the voltage you are measuring from your stator is what you think.
Cheap digital meters (not true rms) use something called form factor correction which is crap when you get significantly away from 50hz.

That said, at low revs it's probably about right.

Blah, blah, i reckon your regulator is duff.

Why is the regulator duff? I agree the regulator caps the voltage but if the maximum output from the stator is 11v what is there to cap ? Duff stator ?

An AC Lambretta stator puts out around 30V (with some revs applied) though it is incredibly unstable. The Reg caps it at 12V. Sometimes 11V, sometimes 13V 'cause they ain't they accurate.

If the readings were taken with it all connected up, then I'd say it's perfectly fine.
As Hendy said, different meters will give different values. On a cheap meter, a reading of 11v would be about 12.2v RMS (equivalence to DC voltage).

mick1 wrote:

hendy wrote:It caps it.
It's not certain that the voltage you are measuring from your stator is what you think.
Cheap digital meters (not true rms) use something called form factor correction which is crap when you get significantly away from 50hz.

That said, at low revs it's probably about right.

Blah, blah, i reckon your regulator is duff.

Why is the regulator duff? I agree the regulator caps the voltage but if the maximum output from the stator is 11v what is there to cap ? Duff stator ?

You're absolutely correct I've no idea why I said it was the regulator. It's the stator output which is low.

firekdp wrote:If the readings were taken with it all connected up, then I'd say it's perfectly fine.
As Hendy said, different meters will give different values. On a cheap meter, a reading of 11v would be about 12.2v RMS (equivalence to DC voltage).

I'm not trying to be smart here, just trying to keep people properly informed, so don't take this as anything else please.

What you say is sometimes correct, but be careful with it. 11v displayed equalling 12.2v will surely be correct occasionally but it depends on a lot of things, for example sampling rate, is the regulator a switched mode type, is the scale skewed on a cheap meter?

All I'm saying is that that type of simplification can lead people up the garden path.

Buy a true rms meter or never expect your results to be better than +/- 0.5v on anything other than dc or mains supplies.

hendy wrote: is the regulator a switched mode type, is the scale skewed on a cheap meter?

I've never been sure what a switched mode regulator is but the type used on Lambrettas is basically a zenor diode arrangement that shorts the excess voltage to earth. I've noticed that they like some load applied in order to get a full voltage reading.

coaster wrote:

hendy wrote: is the regulator a switched mode type, is the scale skewed on a cheap meter?

I've never been sure what a switched mode regulator is but the type used on Lambrettas is basically a zenor diode arrangement that shorts the excess voltage to earth. I've noticed that they like some load applied in order to get a full voltage reading.

There's not a chance that lambrettas have switched mode power supplies. I was just talking in general terms about the sort of thing that can affect meter readings.

Switched mode supplies have 3 basic steps: rectification, pulse width modulation, smoothing. Of course there's a lot of detail around that, but that's a pretty good basic description.

If yours is a half-way rectifier
,you'll never get a decent reading unless you connect a battery and check if the volts increase when you accelerate.