MZB / Powerdynamo Ignition

[DewCatTea-Bob]

" How can I acheive output of 12V/100W for 50 bucks? "

____ How about 12-volts @ 70-watts , (or 140-watts, [depending on how Ducati actually arrived at their "70-watt" rating for the alt]) ?
____ Well anyhow,, for some inexplicable reason, (possibly to avoid over-heating the alt.power-coils), from early-on through until when Ducati replaced the 150-watt alt. on their 860 (with a newer 200w version) in 1976,, they had always chosen to just half-wave rectify the output of their alternators! _ Thus, (unlike with Jap-bikes), HALF of the available power had always been left ignored & untapped!!
__ I'll try to make this explanation a bit easier to understand than it all actually really is.....
____ Your wide-case motor has the 6-coil with 2-windings 70watt-alternator with 1 red & 2 yellow wire-leads...
Each of the 2 yellow-leads connect to just one end each, of the two separate windings (in the alt.stator),, while the single red-lead connects to the two remaining ends (of the 2 windings). _ Since the two windings are connected out-of-phase, that makes it all much like a center-tapped transformer, with the red wire-lead acting as the center-tap.
__ What Ducati's (old) charging-systems do is make use of the positive-pulse that's between the 1st yellow-wire & red-wire, (while ignoring the negative-pulse that's between the red-wire & the 2nd yellow-wire),,
then during the other half of the AC-cycle,
they make use of the positive-pulse that's between the 2nd yellow-wire & the red-wire, (while ignoring the negative-pulse that's between the red-wire & the 1st yellow-wire)!!
This means that only HALF of the current that the alternator can provide, is actually made available for use! _ (As Ducati has it.)
And if we say that the output between the red-wire & either yellow-wire is 6-volts, then it's fair to say that there's 12-volts between the 2 yellow-wires.
Therefore if you ignore the red-wire, (as Ducati effectively did with their 860's 200-watt alt), and connect a FULL-WAVE rectifier, (as most all Jap-bikes do, [instead of the pair of HALF-wave rectifiers that Ducati had always employed]), between the two yellow-wires,, you will then tap into about twice the current, and also obtain about twice the voltage!! - (Since a FW-rect will also allow the utilization of those [otherwise ignored] negative-pulses!)
__ You can buy such a suitable full-wave rectifier-block at places like 'Radio Shack', for well under $10 ! _ You just need a FW.rect-unit which can handle at least 10-amps and with a Peak-Inverse-Voltage of at least 100-volts.
If wired-up in this most simple way, (there are more complex ways!), you'll then likely need a 12v voltage-regulator as well. _ Which can be found at most any cycle-junkyard or on eBay for about 10-bucks. - (I've seen good [used] ones sell for just 99-cents on eBay!)
Then you'll need 12v light-bulbs of course, (I'd recommend one of those new red-led type bulbs for the tail-light),, and you may retain the stock 6v ign.coil by running an automotive-type ballast-resistor in series with the coil.
All simple enough?
Got Questions? _ Please ask!


Cheers,
DCT-Bob

[DewCatTea-Bob]

_____ Thanks a lot for the round-up of the aftermarket-links, Teckhardt !


___ This link is for a 12-pole alternator power-generator...

http://www.classicducati.com/index.php? ... ductId=216

__ While it's power-coils appear to be designed much like the more modern stators on Jap-bikes, I wouldn't choose to use this model on any DUKE of mine because it's produced power-pulses would only be just 30-degrees (of a 360-degree crankshaft-rotation), long! ... Thus barely usable with even the shorter 18-degree ign.advancer-unit, if the intended battery (which this system is obviously meant to work with), goes flat!
__ Although it's power-pulse-frequency would be double that of Ducati's 6-pole alternator and well tolerated by a battery (or capacitor), the DUKE that it gets installed on will become quite more dependent on a pre-charged battery. _ Thus with a discharged (NOT Dead!) battery -(which is capable of taking & holding a charge), a pretty-good running-pushstart (with lights turned-off), might get your engine started,, but ya can probably forget kick-starting it to life! - (Unless maybe the battery & all other loads are disconnected.)


____ This link is for a (WOW!)- 18-POLE model ! ...

http://www.roadandrace.com.au/parts/par ... ingles.htm

__ This model is 50% more so than the one above, with it's power-pulses only just 20-degrees long! _ Thus without the help of a good battery, the ignition-advance should be locked-in to a fixed setting which is not too close to any of the very closely spaced 18 power-nulls where there would happen to be 'ZER0' power occurring (between the end of one power-pulse & the birth of the next). _ This would also make the setting of the phase-timing for a 18-magnet rotor (onto the crankshaft), considerably more technically demanding!
The manufacturer would no doubt claim that their rotor doesn't even require the need to be 'timed' to the crankshaft, and that would be quite true,, as they clearly expect the system which it's to be installed with, to also include a good chargeable battery -(which the ign.system would then surely depend-on)!
___ It seems as though these two manufacturers are thinking of our old DUKE-singles same as they would modern multi-cylinder Jap-bikes with big batteries, electric-starting & electronic-ignition, etc.
Anyone who cares to prove my reasoning to be wrong, please choose the 18-pole model ! _ As I'm very curious to learn how things end-up going for you when your battery happens to leave you stranded.

____ However, it's just occurred to me (after writing all the above), that while the stator-coil is 12 or 18 pole in these cases, their rotors may have only 6 magnetic-poles and then therefore the first-example would be 'duel-phased' and the later-example would be a '3-phase' affair,, in which case there would not be any points-in-time when the (total) power-output could be at ZER0! _ Which means that (at least in the case of the 3-phase set-up), there would be no real problem with what the auto-advancer happens to be doing at any given point-in-time, and, no BIG-problem getting started without a good battery either.
In fact now that I've thought of it, I'd bet that both of these two modern after-market alternators are indeed multi-phased systems and probably both are the 3-phase type - (with the 12-pole model using just 4 magnets).
So if these two examples are indeed phased-systems, (as would seem logical), then I'm sorry for the stuff I first implied about their power-pulses being to short! ... So if they are both actually indeed 3-phase systems, then the 18-pole model's power-pulses are the same -(60-degrees) as a stock 6-pole alt., and the 12-pole model's power-pulses are the same -(90-degrees) as a stock 4-pole system,, (although i'd still bet that their pulses are [individually] weaker than that of the stock [single-phase] alternators).
__ Also, 3-phase alternators would require relatively complex bridge-rectifiers which would no doubt be expensive to replace, and it sure wouldn't be as easy to fine & wire-up a replacement bridge-unit!
__ Also, with a good voltage-regulator, such 'phased' systems would work quite well with 'capacitor' type battery-less systems as well !
If I had to choose (for myself), between either the 12-pole or the 18-pole, (with the cost for either model being the same), I'd prefer the 12-pole version because of it's longer (likely) 90-degree length pulses.


Hopeful Cheers,
DCT-Bob

[dsmess]

If you are worried about kick starting a battery type ignition....and don't want to worry about phasing the flywheel, you might carry along a 2000uf/25V capacitor in your tool kit, to clip in place of the defunct battery. These have been used on British bikes for years.

Scott

[DesmoDog]

" The 250 is listed under both, "

____ Right! _ (So how could a displacement of "250" be considered as both "small" & "big" ?)
Thus I stick with what I had indicated before... "small" refers to narrow-case and "big" refers to wide-case. _ As the 'widecase' motor-case was clearly modified to accept larger flywheel-rotors!

It seems you are correct, I was poking around their site more today and came across a page that lists them as being for narrowcase and widecase trahter than small and large:

http://www.powerdynamo.biz/eng/systems/ ... 47main.htm

I'm quite curious about this system... I've been throwing money at my 350 Bitsa these past few years so what's another few hundred bucks? In for a penny, in for a pound, right?

[DewCatTea-Bob]

" I'm quite curious about this system... "

____ I am as well, so if you lived next-door, I'd push you towards the idea!
However, unless you plan to constantly-run high-power headlight-beams for repeated stop_&_go city-riding, then the only good reason for getting that, is for it's modern ign.system set-up.


High$-Cheers!
-Bob

[DesmoDog]

" I'm quite curious about this system... "

...unless you plan to constantly-run high-power headlight-beams for repeated stop_&_go city-riding, then the only good reason for getting that, is for it's modern ign.system set-up.

I wouldn't constantly be doing that, but... I'm thinking about times when I've been stuck in traffic on another bike where I've been nervous that the battery isn't charging. It's never been an actual problem, (well, except for the time a ground wire broke) but knowing that the electrics are overkill would make for good peace of mind.

Besides, my bike is missing some components so I'm rationalizing to myself that while the $570 or so it costs is certainly expensive, I need to spend money on SOMETHING. So, I can subtract the cost of the alternatives to find what the true added cost of this would be. When I do that it's not too hard to swallow. Only about half of what I originally paid for the entire bike!

[Teckhardt]

This is the system that I am really leaning towards - not for the charging aspect but for the modern ignition and convert to 12v.

You both are welcome to come help me install it when I get it.

BTW - where in the world are you Bob?

[DewCatTea-Bob]

By DesmoDog : ...
" knowing that the electrics are overkill would make for good peace of mind.
Besides, my bike is missing some components so I'm rationalizing to myself that while the $570 or so it costs is certainly expensive, I need to spend money on SOMETHING. So, I can subtract the cost of the alternatives to find what the true added cost of this would be. "

____ I sure can't say that it's not good-reasoning to make such an expensive purchase when that purchase also saves ya from having to buy some other (uncheap) parts which your DUKE-project already needs anyhow !
And in any case, I really wouldn't care to try talking anyone out of buying that very interesting system! _ I just wish to keep it pointed-out that the stock-system -(as Ducati had it), was never set up to take full-advantage of it's entire potential ! _ And that they ought to give it a chance, before-hand.
I do agree that if anyone buys that system, it should be somebody who already NEEDS some key part which that system replaces!
So if that's really your situation, then GO-for-IT ! _ (As I'm sure many of us want to see at least one of us get THEIR feet-wet with such, first!)


Excited-Cheers!
-Bob

[DesmoDog]

I sent an email to a guy in the states who imports them to check on pricing, so we'll see where that goes.

Here's a thought -how many people are seriously considering this system? Perhaps there's a discount for a "group buy" as it were???? I can ask.

Bob - my 250 was missing the regulator (and maybe more?) when I bought it, and the 350 engine I'm putting in it is missing the ignition components, so it seems like a good fit. Plus, I had planed on converting to 12 volts anyway. FWIW, I'm going to soldier on with (modified) 6 volt stock components on my 160, including the points ignition. In fact I spent time today deciphering the thread here on that system.

[DewCatTea-Bob]

By Teckhardt : ...
" This is the system that I am really leaning towards - not for the charging aspect but for the modern ignition and convert to 12v. "

____ I thought YOU were the one who had also found a self-powered modern ign.system -(that's not also part of any charging-system)!?
__ It costs only about 25-bucks to convert to a 12-volt system!


" where in the world are you Bob? "

____ It seems (understandably) that you haven't read all my postings.
While much of my DUCATI-doings were in mid-Ohio, I'm now in lower-W.Michigan.


Cheers,
-Bob