Ducati's FIRST 4-pole Alternator Rated at 40-watts
Posted: Mon Nov 10, 2014 9:00 am
____ I'd like to confer with the buyer of the following eBay-item concerning his intentions with the stator. - http://www.ebay.com/itm/311154913773?ru ... 26_rdc%3D1
__ I believe this was the first stator-type which was constructed by Ducati-themselves and first employed on their later 200-models. _ And although it was rated by Ducati for 40-watts, it's definitely not the same stator-model as the later-designed example that's far-more well-known and commonly referred-to as The '40-watt' model ! _ As that newer-type '40w.model' rather has two separate & independent power-coil windings - (one coil-winding primarily for the ign.system and the other coil-winding just for the main-lights only), which is why I've chosen to refer to it as an 'alternator/magneto-stator' -(or "alt/mag.stator"). _ While the older 40w.version has a pair of windings spread-over a matched-pair of power-coils !
So instead of having separate windings on each of the two power-coils, the older 40w.version rather has both pairs of it's windings spread-over both power-coils. _ And the reason for that somewhat odd (dual) winding-arrangement, is so that the two matched power-windings may thus-then mutually induce power directly into one-another (independently of the power originally induced by the rotor-magnets) when duel half-wave rectified and whilst feeding a load. ...
When there's no load, then of-course there's no current flowing through either winding to induce power into each-other and-thus no 'mutual-induction' then takes place. _ But as the load-system draws more & more current, the desired mutual-induction effect accordingly increases, (which thus-then provides additional induced-power adding-up to more than just that which comes from the action of the spinning mag.rotor alone !). _ So this clever working-action makes Ducati's unique alternator somewhat self-regulating (in that it doesn't produce higher amounts of power unless the load system happens to be consuming higher amounts), as the mutual-induction effect attempts to exactly match the same amount of power as is being consumed. _ So of-course this exceptional setup is capable of producing at-least as much max.power as an otherwise equivalent full-wave rectified stator (which can't self-regulate).
__ But then comes-up the question of why isn't everyone always well satisfied with the power-output of Ducati's alternator !?
Well if they always rode at very-high RPM, then they would indeed always be completely satisfied,, cuz then the mag.rotor induced power would be strong enough to begin with for there to then be more than sufficient mutually-induced power to supplement the power consumed by the load. _ But of-course everyone doesn't run at racing RPM speed most of the time. ...
Unfortunately however, many wish to run powerful headlights whilst riding at low-RPM in the city,, and while the mutual-induction itself would naturally tend to match the current-draw of the high-power headlight, the shortfall comes from the fact that at low-RPM, the rotor-magnets then don't induce enough power into the coil-windings (to at-least HALF-satisfy the load-demand) to begin with ! _ So that thus leaves insufficient power for the load to consume which thusly in-turn leaves accordingly reduced mutual-induction effect to fill-up the power-gap (difference between load-demand & charging-system supply).
__ That's why I've always criticized Ducati for merely half-wave rectifying instead of full-wave rectifying,, as full-wave rectification provides double the power initially to begin-with (regardless of load current-consumption), for best-possible satisfaction of the load-demand near lower-RPMs. _ And that FULLER supply of low-RPM power-output can possibly provide about a 25% power-advantage down-within the low-RPM.range where it's much more apt to be needed (than having some trick-added power-advantage fully operating at higher-RPMs where any increasable power availability is then not really needed anyhow).
Ducati finally realized this more advantageous circumstance in 1976 when they then finally gave-in & updated their 860's 150w dual half-wave rectification charging-system to the 200w full-wave rectification system.
____ I may likely come-back with still more related-stuff concerning this topic, but I've already strayed-off way-more than I had originally meant to include here within this first-post when I first decided to bother with posting this new-thread. _ So I'm going-to quit this now, (for the-time-being).
____ BTW, I'm hoping that Hans/ducwiz has finally come to understand exactly what I've meant in the past whenever I've previously stated "pull/pull" in regards to 'mutual-induction',, and will either confirm that such is indeed inevitable, or offer his-own explanation as to WHY he may still think that such beneficial winding-induction interaction is possibly non-existent.
__ And Hans, this-thread would be more suited for any further discussion of that rare/odd old non-Ducati 175/200 alt.stator (which you've previously mentioned-of within another thread last month).
Enlightening-Cheers,
D.Bob
__ I believe this was the first stator-type which was constructed by Ducati-themselves and first employed on their later 200-models. _ And although it was rated by Ducati for 40-watts, it's definitely not the same stator-model as the later-designed example that's far-more well-known and commonly referred-to as The '40-watt' model ! _ As that newer-type '40w.model' rather has two separate & independent power-coil windings - (one coil-winding primarily for the ign.system and the other coil-winding just for the main-lights only), which is why I've chosen to refer to it as an 'alternator/magneto-stator' -(or "alt/mag.stator"). _ While the older 40w.version has a pair of windings spread-over a matched-pair of power-coils !
So instead of having separate windings on each of the two power-coils, the older 40w.version rather has both pairs of it's windings spread-over both power-coils. _ And the reason for that somewhat odd (dual) winding-arrangement, is so that the two matched power-windings may thus-then mutually induce power directly into one-another (independently of the power originally induced by the rotor-magnets) when duel half-wave rectified and whilst feeding a load. ...
When there's no load, then of-course there's no current flowing through either winding to induce power into each-other and-thus no 'mutual-induction' then takes place. _ But as the load-system draws more & more current, the desired mutual-induction effect accordingly increases, (which thus-then provides additional induced-power adding-up to more than just that which comes from the action of the spinning mag.rotor alone !). _ So this clever working-action makes Ducati's unique alternator somewhat self-regulating (in that it doesn't produce higher amounts of power unless the load system happens to be consuming higher amounts), as the mutual-induction effect attempts to exactly match the same amount of power as is being consumed. _ So of-course this exceptional setup is capable of producing at-least as much max.power as an otherwise equivalent full-wave rectified stator (which can't self-regulate).
__ But then comes-up the question of why isn't everyone always well satisfied with the power-output of Ducati's alternator !?
Well if they always rode at very-high RPM, then they would indeed always be completely satisfied,, cuz then the mag.rotor induced power would be strong enough to begin with for there to then be more than sufficient mutually-induced power to supplement the power consumed by the load. _ But of-course everyone doesn't run at racing RPM speed most of the time. ...
Unfortunately however, many wish to run powerful headlights whilst riding at low-RPM in the city,, and while the mutual-induction itself would naturally tend to match the current-draw of the high-power headlight, the shortfall comes from the fact that at low-RPM, the rotor-magnets then don't induce enough power into the coil-windings (to at-least HALF-satisfy the load-demand) to begin with ! _ So that thus leaves insufficient power for the load to consume which thusly in-turn leaves accordingly reduced mutual-induction effect to fill-up the power-gap (difference between load-demand & charging-system supply).
__ That's why I've always criticized Ducati for merely half-wave rectifying instead of full-wave rectifying,, as full-wave rectification provides double the power initially to begin-with (regardless of load current-consumption), for best-possible satisfaction of the load-demand near lower-RPMs. _ And that FULLER supply of low-RPM power-output can possibly provide about a 25% power-advantage down-within the low-RPM.range where it's much more apt to be needed (than having some trick-added power-advantage fully operating at higher-RPMs where any increasable power availability is then not really needed anyhow).
Ducati finally realized this more advantageous circumstance in 1976 when they then finally gave-in & updated their 860's 150w dual half-wave rectification charging-system to the 200w full-wave rectification system.
____ I may likely come-back with still more related-stuff concerning this topic, but I've already strayed-off way-more than I had originally meant to include here within this first-post when I first decided to bother with posting this new-thread. _ So I'm going-to quit this now, (for the-time-being).
____ BTW, I'm hoping that Hans/ducwiz has finally come to understand exactly what I've meant in the past whenever I've previously stated "pull/pull" in regards to 'mutual-induction',, and will either confirm that such is indeed inevitable, or offer his-own explanation as to WHY he may still think that such beneficial winding-induction interaction is possibly non-existent.
__ And Hans, this-thread would be more suited for any further discussion of that rare/odd old non-Ducati 175/200 alt.stator (which you've previously mentioned-of within another thread last month).
Enlightening-Cheers,
D.Bob