Methods to Increase Power from N-C twin-wirelead Alternators

[DewCatTea-Bob]

NOW REedited, with more info & additioal clarity !

INTRO.....
____ This thread will be mainly intended for varying wiring-methods for getting up to double the amount of power-juice from the Narrow-Case (alternator) models which employ either the 40watt-4pole or the 60watt-6pole alternators which originally include just two (yellow) wire-leads, as was stock on Monza and other N-C models which employ a battery (for powering the ignition-system),, WITHOUT NEED TO MODIFY THE ALTERNATOR'S STATOR !
__ These two types of stock alternators both have just two coil-windings... the older (simpler) 4-pole model has two separate power-coils with one winding each, while the (late-'63-on) 6-pole model has four power-coils, each of which has just two separate (out of phase) windings, which are continuously wound around all four of the coils. - (Thus putting all 4 coils in series [twice, sort of] .)
__ The two separate windings (in either alt.model) are both each connected to one yellow wire-lead, while the opposite end of each winding is grounded (unfortunately deep inside the motor), to their stator.

PART-1.....
_____ While this FIRST method for wiring-up a charging-system, (as I choose to suggest first in this thread), could be wired-up somewhat more simply,, I'm going to explain it the best way which it ought to be done.
__ Somewhat unfortunately, Ducati made both alternator wire-leads the same (yellow) color. _ But their separate outputs are not exactly the same! ... As in the brief-moment when one alt.wire-lead is offering positive-juice -(with respect to ground), the other wire-lead is then offering negative-juice, (and vice-versa) ! _ Also, because Ducati uses a 'NEGative-ground' battery & HALF-wave rectification system, only a certain one of the two alt.wire-leads happens to offer pulses of power-juice that can (help the ign.coil) produce the ign.spark (during the fraction-of-a-moment when-ever the ign.points open) ! _ As Ducati simply ignores all the negative power-pulses from both alt.windings !
__ Anyhow, each of the alternator's two wire-leads are each (separately!) to be connected to one of each of the two separate standard rect.blocks -(intended for this set-up). - (Thus that's wire-lead #1 to rect.block-1, and, wire-lead #2 to rect.block-2. - [One separate rect.block per wire-lead!].) _ Each alt.wire-lead is to be connected (jumped) to BOTH of the AC-inputs of it's own dedicated (full-wave) rect.block.
__ Next the Positive-output of the #1 rect.block will be connected (indirectly) to the POSitive-terminal of the (negative-grounded) battery. - (That connection ought to be switched through a key-switch.)
The POSitive-output of the #2 rect.block should be wired-up so that it's always connected to the battery's (positive) wire-system whenever the lights are turned-on. - (I always preferred to wire-up this auxiliery-power output to a toggle-switch, and only turn it on just when-ever my installed ammeter indicated that the battery was losing it's power-juice/charge, (or, an installed volt-meter shows that the battery is down any less than it's rated-voltage.)
__ Now at just this point, thus far, this suggested system's available power-juice is at least equal to the stock Ducati wiring-system,, (and I believe it to be even somewhat superior to stock because of the lack of Ducati's so-called "Voltage-Regulator" -[black-box] which actually impedes the flow of any charging-current, [rather than directly control system-voltage] ).

PART-2.....
____ Next, we now get to the more interesting, non-conventional means of getting ADDITIONAL power-juice from the stock (unmodified) alternator, for other possible uses, such as running the ignition-system independently (from the battery&lights), or even an entire alternate electrical-system including it's own [almost completely]- separate ignition-system for a 2nd ign.plug !)...
__ At this point we next have all the negative power-juice that's become available from the NEGative-outputs of each of the two rect.blocks !
This additional-power (by itself) is at least equal to that of the stock-system, (it's just NEGATIVE [with respect to 'ground'], instead of positive !). _ And this 'negative' power-juice is actually "ADDITIONAL" because, it's always been COMPLETELY ignored by Ducati's stock-system !
With this additional power-juice, the total amount of available power-juice is at least equal to TWICE that of the stock Ducati-system !
The only thing is however, is that what we have at this point are TWO separate & uncombinable (pairs of) power-juice outputs, (due to the fact that the pair of alt.winding lead-ends are GROUNDED!)... One pair of outputs which are Negative-to-ground (like stock), AND, another pair of outputs which are Positive-to-ground, (like Brit-bikes). _ Thus you could think of this set-up as either, a 'dual-system', or, a '2-in-1 system' .
__ So what ought to be done is let the normal negative-ground system be just for the battery; lights; & horn,, while the positive-ground (extra)- system may run the ignition (with either a second-battery, or perhaps preferrably with a battery-eliminator -[made for a Brit-bike] ), and perhaps an aux.brake-light or something, as well. - (With plenty of power-juice left over !)
__ With this useful set-up, brighter lights can be used without concern of robbing ANY power-juice from the ignition - (so no need at all to have lights-off while trying to get the engine started), plus, the ignition-system will not depend (any at all) on the battery -(that's used for powering the main-lights) !!
____ This dual-system can be set-up for 6 and/or 12 volts, however at lower RPMs down where the peaks of the alt.power-pulses are still high enough to force charging-current through a 6-volt battery,, a 12-volt battery, (at the same point), will no longer take-in any charging-juice. _ But that's really not all as bad as it seems to be, because of the following reasons...
A 6-volt battery that's taking-in power-juice (while charging) is adding itself to the system's loads, (as a battery can't save as much power-juice as it takes-in !),, while with a 12-volt battery, that otherwise lost power-juice is instead left to be consumed by the system-loads, and thus saving the battery from as much discharge. _ Plus, there's only a small difference of extra RPM needed to reach the charging-point for a 12-volt battery, because it's not (before then) acting as one of the system loads, (until after the power-pulse voltage-peaks exceed the voltage of the battery) ! _ (Where-as a 6-volt battery indeed would be a system load within that narrow RPM-range -[where a 6-volt battery would charge but a 12-volt battery would not]!)
__ So anyhow, if for mainly low-RPM city-riding, a 6volt-system would be a bit better,, however at the same time, then also more likely (than a 12-volt system) to make some good use of a voltage-regulator when-ever long-distance @ high-RPM riding is performed.
But don't forget, with this dual-system, keeping the battery charged (during low-rev riding) would no longer be as important,, since there would be no more worry about having your DUKE-engine die-off on ya, due to the lights running-down the battery ! n

____ Any questions?

____ While all of the above part of this post is only about just my 2-in-1 dual-system,, I'll tell of a better 12volt-system (which however requires modification of these stator types), if anyone requests info on such. _ And while a more conventional system, I however have always preferred the advantages of my useful 'dual-system' !


DUKE-Cheers,
DCT-Bob

[bettyann]

Dew cat Tee Bob
On your thread, the first half is as clear as crystal. The second half: do you mean to add more info on the system about Improving the two yellow wires one connected to each full wave bridge rectifier. Than add more wires to the negatives or were you talking about a whole different system, than the first one?
Also I bought 2 25amp 50v full wave Bridge rectifiers, now where do I get brit bike battery eliminators? Capt Paul

[DewCatTea-Bob]

This reply-post has now been EDITED for better clarity.


" On your thread, the first half is as clear as crystal. The second half: do you mean to add more info on the system about Improving the two yellow wires one connected to each full wave bridge rectifier. Than add more wires to the negatives or were you talking about a whole different system, than the first one? "

____ I'm not really too clear on exactly what you're asking me to clarify here, so in hopes of covering what-ever is not clear to you, I'll just state the following for now.....
____ While I did indeed start this thread to cover more than one type of a modified "system" for use with the STOCK "twin wire-lead" alternators, I surely would never allow for any confusion to possibly occur by providing details concerning more than one completely-different electrical-system, within the very same POSTing (under this thread) ! _ As doing so would certainly allow most any reader to get the varying details fairly confused ! _ Therefore you should always expect that I will have taken steps to help prevent careful readers from confusing things.
__ I always try to do everything thought-out as logically as possible! - (As all my obviously logically-placed extra punctuation & spacing should always help make clear !) _ And I don't just throw-out half thought-out thoughts as-is, directly onto my posts,, which could then of course more likely leave the wording so as to be only correctly-understood by just my own self, (as it often seems too many others obviously must do).
So that should help ya to realize that ya don't have to work your brain as much, trying to determine if your interpretation of my wording has actually been CORRECTLY understood or not. And thus there should be less chance of considering any possible misinterpretations.
(But even so, it seems that when-ever I later reread my own posts, I then always seem to still notice something which I should've written somewhat differently, and thus often feel the need to do some editing.)

____ You indicated that "the first half" is "clear"... I assume that you mean the first-part concerning the standard negative-ground portion of my thus described 'dual-system', (since that half/part of my system/post concerns only the more conventionally known aspect, thus that's not as difficult to firmly grasp).
So I'm left to assume that you've found some details within the second-part to be insufficiently clear enough and thus left you somewhat wondering for additional/clarifying details, (which of course must then have something to do with the later part of my explanation concerning the unconventional use of TWO separate full-wave rect.blocks to simultaneously obtain BOTH a standard Negative-to-ground as well as the EXTRA non-standard Positive-to-ground, dual type set-up, for getting the two separate power-juice systems), as that later part of my post covering the positive-ground aspect, is (understandably more likely) relatively confusing.
__ Well actually, "TWO" FW-rect.blocks are not really needed ! _ And so all 8 internal diodes are not really required for this intended "dual-system" either. _ (I only choose to use the fullwave-bridge rect.blocks because they are cheap and easy to mount & wire-up as well !)
Only one rect.block is REALLY needed, so we could get-by with using just one rect.block unit, (which would put all 4 of it's diodes to use!). _ But then the system would be less flexable as well.
With the simpler set-up (of using only one rect-block), one alt.wire-lead would be connected to one of the rect.block's AC-inputs, while the other alt.wire-lead would be connected to the rect-block's other AC-input.
Then, (with respect to ground), the rect.block's Positive-output would then provide a full-wave type pulsating DC-output (just the same as the stock pair of power-diodes [in the black-box] do!),, PLUS also, the rect.block's Negative-output would provide a (second & separate) full-wave type pulsating DC-output, as well ! _ Only thing is, is that THIS added power-juice HAS to be used for a totally separate set of loads! _ (So can ya think of any use for that otherwise ignored power-juice? - A second headlight? , A second ignition-coil? )
___ Now in case anyone is a little lost & unsure,, the later wording about using just one rect.block unit, is ALSO for obtaining pretty-much the same 2-in-1 dual-system as my first-post (in this same thread) was ! _ It's just that with my preferred (dual rect.block) dual-system, it's then possible to split-up the DC-output of both the Positive-system and the Negative-system, for possible additional options !
____ I hope the above helps to clear-up any previous confusion.


" now where do I get brit bike battery eliminators? "

____ They used to be quite a very popular item before the '80s !_ There were cheap units as well as relatively complex models!
The real cheap units were nothing more than a 2000uF capacitor, while the top-line bat.eliminators had a pair of capacitors -(a .01F & a .025F), plus an AC-choke & a 6 or 12 volt power-zenerdiode -(to act as a voltage-regulator, [since there'd no longer be a battery to hold-down system-voltage] ). ...
__ I would hope that most Brit-bike dealers would still have new or used B.E.units for sale! _ I used to get such units intended for late-model BSAs, before later just making my own.
I suggest running a search on eBay for: 'BSA battery eliminator' , (for example). _ But be careful, as I've seen other miscellanious units mis-titled on eBay !
One could simply buy the parts and make their own equivalent of such, for less !
__ But before becoming too concerned about getting such a B.E.unit, you might consider instead using some of the normally ignored negative power-juice to power the ignition, much in the same manor as the non-battery-powered DUKE-models do !

____ Any more questions? _ (I know if I were the person who I once was before I came to learn everything that I know now, I sure would have a whole-lot of questions!)


Hopeful-Cheers,
DCT-Bob

( I have recently REedited my first post [on this thread], to make more & better sense, as well as this post now too !)

[bettyann]

Dew cat Tee Bob;

Bob I've got it down pat, Now as I under stand each of the bridge blocks will have a yellow wire to a/c pole, a ground to the remaining a/c poles.Then a (red)wire from the pos pole of i bridge block through a switch to battery, the other pos pole gets a (red) wire to augment the battery when the lights are on. Now each bridge blocks unused neg poles Could add an extra power supply to power maybe horn/brake light. The remaining neg pole could go through a British bike battery eliminator to run the ignition all by it self. Now I have 2 questions. Using a multi-meter, how do I detect the wire to the british bike eliminator, and the system friendly battery power for brake/horn? #2 Write down the part descriptions to build a brit bike eliminator. My best friend is a tv repair man, and he could make it for me. Thank You Capt Paul
P.S. will 16 Gauge wire be ok? Or 14 to the Battery?

[wcorey]

If by 'brit bike eliminator' you mean a battery eliminator capacitor then it is just a 50v 20k to 30k microfarad capacitor with one lead installed anywhere on the power wire going to the coil, the other lead going to ground. Mind that you wire it with proper polarity to power and ground depending if you are running the ignition with positive or negative ground since these alternator mods could end up using both.

[DewCatTea-Bob]

NOTE: This reply-post has now been edited to make better sense, and also add some more details !


" each of the bridge blocks will have a yellow wire to a/c pole, "

____ Well yes, of course, I'm sure you understand that properly, but, since (here) we are concerned with the system-plan which uses TWO rect.blocks, I'd prefer to clarify this with the following wording...
Each of the (two separate full-wave bridge) rectifier-blocks will have only one alternator (yellow)- wire-lead connected to either (or both) of it's AC-terminals !
(Side-Note... If the chosen rect.block is rated to handle just 3 to 8 amps, then it is required that it's connected alt.wire-lead be jumped to BOTH of it's AC-inputs. _ However, connection to both of the rect.block's AC-inputs isn't really important, if the rect.blocks are rated at 10 to 25 amps.)


" a ground to the remaining a/c poles."

____ If by "a/c poles" , you're actually meaning the 'AC-input terminal-posts' on either of the rect.blocks, then NO, not with this intended set-up. _ However if you mean the alternator's 'AC-poles lead-ends', then yes, but, those should already be grounded (at the stator) !


" Then a (red)wire from the pos pole of i bridge block through a switch to battery,"

____ Yes, however I have a couple side notes... On DUKEs it's been fairly-well established that YELLOW is for AC, and RED is for 'B+' (that's Battery-DC),, so then ORANGE ought to be the logical color chosen for P.DC, which is the waveform-output of rectifiers !
And also, the reason for a switch between the rectifier-output & the battery, is to keep the battery from running-down, (back through the rectifier). _ So that's a useful function for a key-switch -(that's used for the ignition), to include !


" the other pos pole gets a (red) wire to augment the battery when the lights are on."

____ Assuming that you actually mean the positive-output terminal-post of the alternate/2nd rect.block, then YES!
That augmenting positive-output should also be run through another separate ORANGE-wire to ANOTHER switch, (so that that extra positive power-juice can then only be used to help keep the battery charged when-ever the lights are turned-on).


" Now each bridge blocks unused neg poles Could add an extra power supply to power maybe horn/brake light. "

____ Options, options & still more,, it seems with this 2-in-1 dual-system, that there's too many options to choose from for the limited number of loads ! _ Yet many of all the very many wiring-options pretty-much line-up themselves, when-ever good logical-thought is applied with regards to the particular (preselected & chosen) electrical-parts & goal choices, (which really should all be concluded before deciding the best way to go with the wiring-choices) !
Such as 40-watt or 60-watt alternator ? , 6 volt or 12 ? , 1 battery or 2 ? , 1 B.E. or 2 ? , 1 ign.coil or 2 ? , Stock lighting, or modern ? , In-town street-riding, or back-road racing ? _ Etc., Etc.
So AFTER ya know exactly what all your electrical-parts & goals are intended to be, THEN it would be more sensible to decide how best to wire-up everything !
__ You do have the choice of combining both negative-outputs of the pair of rect.blocks, to then run a (completely) separate system with a good Brit-bike battery-eliminator,, or, keep the outputs separate, with one for the ignition-system, and the other for a (positive-ground)- battery-system or some other load.
But the "horn/brake light" loads should already be well handled by the primary/1st POSitive-output (of the 1st rect.block), since that's connected with the intended (primary) battery ! _ As those two loads (especially horn), should be powered by a battery !


" The remaining neg pole could go through a British bike battery eliminator to run the ignition all by it self. "

____ Well yes but, it could depend on which one you choose... Of those two separate negative-outputs (from the two rect.blocks), ONE of them would not properly power the ignition (without help from a battery), because it's power-pulse is not correctly 'timed' with the ign.spark ! _ While the other rect.block's (correctly phased) negative-output could run the ignition without the need for any help from a battery, (or even a B.E.capacitor, providing that the alternator is the 4-pole type) !
__ However with the 6-pole alternator, either rect.block's output should run the ignition with the help of a good battery-eliminator. _ That's because the 6-pole alternator produces more power-pulses -(12) from each of it's two wire-leads, per (4-cycle) ign.spark ! _ And that in turn of course also means that there's 12 power-pulses available from either of the two rect.blocks as well, (between each ign.spark) ! ... So that's 6-positive OR 6-negative power-pulses from one OR the other of each rect.block's two separate output-terminals... And so a battery-eliminator fed by ONE of those outputs, would then receive 6 half-wave pulses of DC power-juice per ign.spark ! - Actually, (due to the duration of the lobe on the points cam), those 6 power-pulses are split-up to provide nearly 4 full power-pulses for storing a charge within a B.E.capacitor, plus slightly over 2 power-pulses for assisting that stored-charge, to saturate the ign.coil. _ But, (depending on which alternator-winding is actually being tapped for the job), ONE rect.block's negative output would happen to be dead at the instant when the points open ! _ That's because BOTH negative-outputs (of the two rect. blocks) cannot supply, (at the same time), a negative power-pulse which is properly phase-timed with the ign.spark's timing ! - (As those two outputs are 180-degrees out-of-phase!)
So, it's preferred that the particular rect.block negative-output which happens to have a negative power-pulse occurring at the same time as the ign.spark, be the same one that's chosen to work with the battery-eliminator, (if used for running the ignition-system).


" Using a multi-meter, how do I detect the wire to the british bike eliminator, "

____ Well it seems that you must already have a fairly-good understanding, even before having read & understood that which I've just covered above ! _ As you apparently realize why it matters which P.DC output is used for powering the ignition.
But I'm sorry to tell you that ya can't figure-out which output is the preferred one, with any such meter !
__ Since Ducati used the same color for both alt.winding wire-leads,, the only way then to learn which of the two separate negative-outputs to favor for the ignition-circuit, is to connect one at a time directly to the ign.coil and see which one is actually capable of running the engine. - (If the alt.rotor is still correctly phase-timed to the crankshaft, then ONE of the two half-wave P.DC-outputs should not make a usable spark !)


" Write down the part descriptions to build a brit bike eliminator. My best friend is a tv repair man, and he could make it for me. "

____ I see that 'wcorey' has already posted the primary part (for the ignition aspect) of such a unit. _ If you want your B.E.unit to be used with lights as well, then the addition of a power-zenerdiode -(6 to 7-volt / 8 to 12-amp, OR, 12 to 14-volt / 4 to 8-amp) should make a suitable B.E.curcuit. _ But keep in mind that if your battery-eliminator has to run any lights as well, then they NEED to be turned-OFF when-ever trying to start your engine ! _ (As any other such loads will bleed-off most of the power-juice that's being saved within the B.E.capacitor, leaving next-to-none left for powering your ign.coil, at kick-starting RPM !)
__ These parts are way much higher power handling components than TVs & such ever use ! _ (I too was also a TV-man!) _ So while your friend in that field would certainly understand how to create a B.E.-circuit for your DUKE, he probably won't have a common source for such high-power components.
Also, I'm sure that modern B.E.units, (if they're still making such), are more complex (with added electronics), than I ever knew them to be.


" will 16 Gauge wire be ok? Or 14 to the Battery? "

____ For 6-volt battery, 14Ga,, & 16Ga for lights / horn...
For 12-volt battery, 16Ga,, & 18Ga for lights / horn ,
are adequate sizes.

____ If you like, just tell me all the parts which you wish to use, and what kind of riding you mainly intend for the DUKE in question,, and I'll then tell you what I think your best arrangement ought to be. _ (As certainly no cycle-manufacturer would proceed-onward without such planning [BEFORE production]!)


DUKE-Cheers,
DCT-Bob

[bettyann]

Dew cat Tee Bob

Let's make this simple, I have a 40w alt 2 yellow wires.

Now 2 bridge rectifiers side by side, Top left a/c --- top right pos + ----------- top left a/c - - top right pos +

#1 #2
25amps-50volt full wave
bridge recitifiers
------- --------- bottom left neg--- bottom right a/c. --------- bottom left neg -- bottom right a/c

Now 1 yellow wire from alt to top left a/c ok? --- top right pos red batt wire switched bridge #1



Then 2nd yellow wire to top left a/c --------- top right pos red to be switched to headlight bridge # 2

Now what do I connect to bottom left neg, and bottom left a/c to on these two full wave bridge rectifiers, fill in the blanks
Please, your a very smart man just tell me in every day language what wires go on the other connectors Thank You Capt Paul

[DewCatTea-Bob]

" just tell me in every day language what wires go on the other connectors "

____ Sorry it seems that I've placed the tree-branch which you wish to examine, within the edge of my forest of info on the subject... Thus you must have overlooked that I've already covered all the ins & outs that I could, without knowing what all your other intended parts are going to be !
So as I've mentioned, it would help to know exactly what you wish to achieve, cuz there are a few other related systems which may suit your desire somewhat better ! ...
Am I to assume you're sticking with 6-volts and stock lighting ?
And it would also be useful to know if your stator is out & available for modification, or still buttoned-up within it's motor which you wish to leave put-together. _ ?
__ What may be somewhat confusing is your use of the term "bridge"... While the 'rect.blocks' which I refer to are indeed full-wave bridge-rectifiers, in this particular case they are not to be used as a so-called "bridge" , at all !
__ I'm sorry but, it will take me some time to figure-out exactly what your last post is actually ALL about. _ (Hopefully it's more obvious to somebody-else who can clue-me-in! _ ?)
Would it help you much better if I attempted a diagram concerning just the parts in question?
Otherwise, I can only repeat what I've already indicated previously before, with other wording, here next....
__ As I'm sure you realize by now, each rect.block has only 4 terminal-posts...
_2 - AC-inputs, and,
_1 - POSitive-output, and,
_1 - NEGative-output .
__ So in this case which has been (mainly) covered thus far (within this thread),, both of the intended rect.blocks are to have the same -(corresponding) type of wire-conncetions ! ... And this is...
_ ONE YELLOW alt.wire-lead connected to BOTH (or just one, [it doesn't actually matter!],) of the rect.block's AC-inputs. - (For the purpose of rectifying the alternator's AC-juice.) ;
_ ONE (orange & red)- wire connected to the rect.block's POSitive-output. - (For the purpose of supplying positive HALF-wave Pulsating-DC to a (NEG.Ground)-battery's POS.pole-post, and/or loads.) ;
_ ONE (orange & black)- wire connected to the rect.block's NEGative-output. - (For the purpose of supplying negative HALF-wave Pulsating-DC to a (POS.Ground)-battery's NEG.pole-post, and/or loads.)
Once again, all the above is ditto for the extra rect.block (for the OTHER yellow wire-lead) ! _ And so NOW that's it, I can't make it any more simpler to have CORRECTLY-understood !
So I hope that helps!

____ I wonder if there's anyone else out there with an opinion on who's post (within this thread) is the hardest to understand concerning EXACTLY what's trying to be conveyed!?


DUKE-Cheers,
DCT-Bob

[DewCatTea-Bob]

PLEASE NOTE that THIS is a NEWer/SEPARATE posting made to be included under this same thread !
Please realize that each new-post (that's not a 'reply-post') which I start under this thread, is meant for introducing another somewhat DIFFERENT proposed system.

____ I started this thread to cover several separate & varied versions on several different electrical-systems to choose from for DUKEs fitted with either of the two Ducati-alternators which have just one PAIR of wire-leads.
__ I guess I should've started-off this thread with the simplest system, and from there explore-on to more complicated systems which have more options. _ But I started it off with my favorite version of systems for these type of alternators.
I realize that most DUKE-owners don't care to wire-up systems that are more complicated than being as simple as possible, so THIS post will concern a simplified version of the first/previous system/post.....


____ This is: 'Post/version #2' , of system 'A' ! - (My long-time personal favorite system!)

INTRO.......

____ Alright, next, since I was not previously supplied with full details on what the actual goals are for the intended project,, then at this point I'll take a guess at what the scenario might actually be.....
__ I suspect that we have an old 4-speed Monza, (which are known to have come stock with a twin-lead type 40-watt 4-pole alternator, of which it's two power-coil windings are both grounded [unfortunately] at their coils).
And this old DUKE is missing most all it's original wiring & other electrical parts. _ So it's owner now needs to come-up with a means to run a replacement electrical-system for his project-Monza !
Currently, the main-concern is for a new charging-system that's at least as strong as stock, yet without having to pull-out the alternator & modify it's stator.
So what we'll do is first use modern (& cheap) parts which are easy to install and yet will do the required job at least as well as the Monza's stock 40-watt system had done, and from there then consider other possible ways to even further improve the total power of the new electrical-system!
____ So as to better understand this particular Ducati-alternator and it's effects with the elecrical-system, I'll make some points concerning it.....
It has two completely separate power-coils which are arranged so that their outputs are out of phase... That means that at some instant-point in time when one power-coil's output happens to be positive, then the other one's output is negative !
Now since this alternator has a '4-pole' rotor, then each power-coil will produce 2 full AC-cycles per complete revolution of the crankshaft ! _ And worthy of note then, is that since 1 AC-cycle has 2 power-pulses, and that it takes 2 crankshaft revs to complete an ignition-cycle,, that then means that EACH alt.power-coil produces 8 power-pulses per ign.spark ! _ (And the entire alternator then of course supplies 8-positive & 8-negative power-pulses per ign.spark!)
(However, Ducati's original-system only makes use of just the alternator's positive power-pulses ! )

PART-1.....
____ For this particular DUKE-project, we could make full use of a single commonly available rectifier-block (which happens to contain 4 diodes arranged in what's called a 'bridge' ). _ We could get by with just two power-diodes (for this "PART-!") but, the block-of-4 is about as cheap, and also easier to use, (and actually needed for "PART-2") !
The neat little rect.block has 4 terminal-posts (which are each connected to one of the block's 4 internal poles). _ The block has 2 terminal-posts for connection to AC sources, and one terminal-post for negative DC-output, plus another for it's positive DC-output !
__ To be connected to each of the rect.block's pair of AC-input terminal-posts, is one of the pair of stock YELLOW alt.wire-leads. - (So that's actually 1 alt.wire-lead to 1 AC-input terminal-post, and, the other alt.wire-lead to the opposite AC-input, of the [single] rect.block [of this particular system].) _ And it doesn't matter which alt.wire-lead gets connected to which AC-input !
Next, to the rect.block's POSitive terminal-post, is connected both a RED & a GREY -(as like stock) colored wires, which will feed a 6-volt battery & stock loads with POSITIVE full-wave type Pulsating-DC ! - (That's full-wave "TYPE" P.DC, as it's not actually the normal/real 'full-wave' P.DC, but rather, the combination of two separate half-wave P.DC outputs that [together] only appear to be as 'full-wave', because the 2 half-waves are spaced 180-degrees out of phase from each other !)
__ Now at this conclusion of 'PART-1', so far, (with the exception of the 'choking-EFFECT' which the clever Ducati excess CURRENT-repulsor [within the stock twin power-diode rectifier, black-box], has), we have AT LEAST the same amount of power-juice as the original stock Ducati-system,, to run a COMPLETE electrical-system !
__ With that which we have up to this point, the only issue of possible concern is over-charging of the battery during extended high-RPM riding with lights off.
To address this concern, we could simply use a toggle-switch to disconnect one of the alternator's yellow wire-leads from either of the rect.block's two AC-inputs,, for when-ever the lights are not being used (to help consume the alternator's power-juice [so that the battery won't have to!] ).
However, the yellow wire-lead that should be made switchable, should be the one that's not phased for helping the ignition-spark.

PART-2 .....
____ Next, (now that the POSITIVE-output of the rect.block has been addressed), we can decide how the NEGATIVE power-juice (provided by the rect.block's NEG.output), can be best taken advantage of.
There are a fair number of different ways that the total available power-juice could be distributed, and so it much depends on what all is actually desired to be accomplished, before-hand.
I myself would wish for the ignition to not be dependent on a battery ! _ And with this 4-pole alternator, there's two different ways to do that...
1 - We could use a Brit-bike (positive-ground) battery-eliminator (powered by the rect.block's NEGative-output) to run the (RED-coil)- ignition-system. _ (I have done that and also used the B.E.unit's output to power an extra brake-light placed in the headlamp.)
2 - We could use a second rect.block (in order to be able to split-up the half-wave power-juice from each alt.power-coil), which would prevent the waste of power-juice while running a Mk3/SCR type (GREEN-coil)- ignition-system. - (Side-note... That would [unneededly] still feed the ignition-system with 3 extra power-pulses per spark, as that Mk3/SCR type ign.system actually only requires just a single power-pulse per spark !)
And with the un-wasted 4 power-pulses per spark, that saved power-juice could then be used to charge a capacitor for powering an extra load (such as a brake-light switch activated light in the head-lamp, [as I always preferred to do!] ).

CLOSING-Notes.....
____ The next part will follow later, as I will then tell of many ways to make good -(cool & neat) uses of the power-juice that's available from the stock alternator, but which Ducati never bothered to make any use of on any of their motorcycles until 1976 !
__ I contend that when-ever anyone tells of Ducati power-juice systems as being 'weak', that it's not really the fault of their alternators ability to produce power, but rather, actually due to the fact that Ducati's related wiring-systems only make use of just HALF or their alternator's power-potential !!
Thus it seems that in this case, Ducati rated their 4-pole alternator by reasoning that the power-coil employed can produce 40-watts AC (at some RPM-range), but since they choose to only make use of HALF of it's power-juice, the fact that the alternator has 2 such power-coils, means that the whole alternator still then provides just 40-watts total ! _ (That's 40watts x 2 = 80 x 1/2 = 40-watts , thus the so-called "40 watt" alternator !)


DUCATIly,
DCT-Bob

[bettyann]

To the rect.block's pair of AC-input terminal-posts, are each connected to one of the pair of stock YELLOW alt.wire-leads. - (That's 1 wire-lead to 1 terminal-post, done twice!) _ And it does NOT matter which goes to which "!Dew cat Tee Bob"


__ok this means a yellow wire from 62 monza duke 40w alt is connected to both a/c terminals on #1 bridge rec, and the other yellow wire from the alt is connected to both a/c terminals on bridge #2! (can they be jumped from the a/c terminals on each bridge?)


Next, to the rect.block's Positive terminal-post, is connected both a RED & a GREY -(as stock) wires, which will feed a 6-volt battery & stock loads (with POSITIVE full-wave type Pulsating-DC !)."Dew cat Tee Bob"

___ok this means a red wire to bridge #1positive post to recharge the battery!
next a gray wire from bridge #2 positive to say to headlight switch to brighten lights
Am I ok so far? Capt Paul Thank You BoB