Postby DewCatTea-Bob » Wed Aug 06, 2014 1:01 am
____ Sorry I didn't notice your new post sooner, as it must've gotten posted on this new page whilst I was still editing my previous post on page-2 (before I finally 'signed-off' on that post) !
[quote= narrow_monza ...
" I will wire up the bridge-block and check for a spark.
I'm assuming I don't need to have the battery in the circuit for the purpose of this test, "
____ You've assumed correctly, so forget the battery for now,, as the battery will be part of another/UNinvolved circuit (which has nothing to do with your ign.system) !
" just the 2 diodes from the AC inputs to the negative output, right? "
____ The AC.power wire-lead from the ign.power-coil should terminate to one or both AC.inputs of the bridge-block,, and-then (preferably*) the b.block's negative-output, (* not it's '+' output), connects to the ign.system (at the same connection-point as where the AC.power-lead did).
__ Whether you still get ign.spark or not,, you ought-to also try-out connecting just the b.block's POS.output to the ign.system as well, so as to confirm that only one output or the other will allow the ign.system to create a spark, (thus confirming that the b.block's diodes are functioning as expected).
There's at-least a 50%-chance that the 'neg.output' will still allow spark to be created,, but if IT doesn't, then you'd either have-to consider a positive-ground battery-circuit, OR-else rotate the mag.rotor a quarter-turn (in relation to the crankshaft [AND-thus also in relationship to the points-cam orientation as well] ).
__ Please let us know how these tests turn-out for you.
____ I often wait to-be inspired by posted-questions, leading to becoming motivated enough to post extra tech.details,, but I've already waited too long to get the following related-stuff posted.
__ Here's some tech.detailing as to what's going-on with the diode-steering of the NEG & POS component-halves of the AC.power...
The ign.power-coil of Ducati's four-pole alternator creates 2 complete AC.cycles per revolution,, so-thus every time an ign.spark is created, there's been 4 complete AC.cycles consisting of 4 positive & 4 negative power-pulses ! _ And normally (as stock), ALL of those power-pulses are left allowed to be dumped towards the powering of the (non-battery type) ign.system, even-though the ign.system only requires merely a portion of JUST one power-pulse (per 4-stroke/Otto-cycle) !!
So considering the dwell-ratio of the points-cam,, that means that two of the un-required power-pulses are wasted through the ign.coil circuit to ground, and the remaining five p.pulses are rather more directly wasted to ground (by 'SHORT-circuit' through the contact-points) !!
__ Of-course it would be most desirable to save & utilize all seven of the excess power-pulses (per Otto-cycle), but the diodes can only separate the positive-pulses from the negative-pulses,, so-thus three of the NEG*pulses still have-to be allowed to go to waste. _ However all four of the POS*pulses can be saved & diverted to power something-else (such-as battery-charging) !
(** NOTE that if the N. & S. magnetic phase relationship of the mag.rotor is located (on the crankshaft) 90-degrees off, then the POS & NEG roles are thusly reversed.)
Enlightening-Cheers,
DCT-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob