>Funny thing - last night I downloaded the corrected Z-7 drawing you had
>announced in your message, and tonight I find this new message from you
>announcing the latest, once more "revised" version of the same drawing. Of
>course, I just HAD to download that one too, and - lo and behold! - this
>turns out to be nothing new but rather exactly the setup you sent me some
>years ago, and which I then fitted to my Rotax 2-stroke-engined Kitfox.
Hmmm . . . first thing to go when you get old is your memory,
and I forget what the second thing was . . .
I do seem to recall having that conversation with you and
probably with several others over the years . . . don't know
why I missed getting that incorporated earlier. I guess
I still hoped that people would have some form of l.v. warning
which does the same thing . . . the system will go into
low volts a seconds after the alternator trips off line.
>All I can say is that I can really recommend this system to anyone using one
>of these whizz engines. On my airplane, I had no less than two total
>failures of the infamous "cheapie" regulator supplied as standard by Rotax,
>plus a couple of intermittent instances of overvoltage. The "crowbar" setup
>did its trick exactly as it is supposed to do, and I must confess that in at
>least one of these occurrences I would surely not have caught the failure
>condition before some damage would have been inflicted.
I'd REALLY like to figure out a way to do a REAL rectifier/regulator
for that engine. The #1 problem is HEAT. With one diode and one
SCR in conduction on each half-cycle of the AC out, there's a total
of about 2 volts dropped. Multiplied by 18 amps and you've got
36 watts of heat to dump. I think most people are having trouble
with their designs because of inadequate heat managment.
I'd also like to see the trigger system for the SCR get smarter.
I don't see any reason why that regulator shouldn't be as tightly
in command of bus voltage as it's automotive counterparts . . .
+/- 100 mV is in order. One of these days . . .
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