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cffd66(at)yahoo.com
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 Posted: Sun Oct 20, 2013 11:07 am Post subject: Jabiru 2200 voltage regulator again |
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I have Jabiru 2200 serial # 988 which has the 10 amp alternator. I have the circuit diagram of the Kabota regulator. Is there a writeup on how the regulator works? It appears to have a differential amplifier to sense the bus voltage and the then compares it to the AC coming from the alternator. I just don't understand how the zener diode provides a reference without a resistor to control the current through the zener and also how the AC wave is compared to the reference. But then again I have always have had problems with PNP circuits.
Chuck D.
Further study shows that Q1 and Q2 are to light a low voltage lite and are not part of a differential amplifier. Q3 and Q4 are for the regulator. My comment about the current limit on the zener still stands. circuit is from: http://www.aeroelectric.com/Pictures/Schematics/PM_Regulator/Kubota_Schematic.jpg
Chuck D.
[quote][b]
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nuckolls.bob(at)aeroelect
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| Posted: Sun Oct 20, 2013 2:00 pm Post subject: Jabiru 2200 voltage regulator again |
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Yes, the circuit was dissected into two
functions at:
http://tinyurl.com/c8usyw2
http://tinyurl.com/c6doa97
. . . and you're right. The base-emitter junction of
Q4 in series with the hopefully small dynamic resistance
of the zener places the transistor at serious risk. This design
would not even come close to passing DO160 input voltage
tests. But then, not many garden tractors are subject
to the kinds of trash on the bus as airplanes.
I've not seen a schematic for a PM regulator that
offers warm-fuzzy feelings to an airplane jockey.
These bang-bang regulators have proven quite sufficient
for the lawn equipment markets and few folks have
complained about them in airplanes . . . at least
few to none here on the List. They may have a field
service history one step above dismal but not articulated
here.
If you're pondering a DIY project for a PM regulator,
consider adding some impedance in series with the
base of Q4. It doesn't need to be very big. The way
this thing is wired, the zener's operating current
is VERY low . . . a milliamp or less. Also poor design
practice . . . this is not up on the knee for predictable
conduction at the rated voltage. So 100 ohms in series
would protect the transistor and have very little
effect on regulation.
An adjustable regulator might modify the input circuit
to include a potentiometer which would add useful
base current protection for Q4. If you're up to brass-boarding
some experiments, I've had a few ideas for an upgrading
of the circuit's performance.
Bob . . .
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earl_schroeder(at)juno.co
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| Posted: Mon Oct 21, 2013 5:56 am Post subject: Jabiru 2200 voltage regulator again |
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I know a number of us would like to improve the Rotax regs...
Please continue! Thanks.
| Quote: | On Oct 20, 2013, at 3:37 PM, "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> wrote:
>
> Further study shows that Q1 and Q2 are to light a low voltage lite and are not part of a differential amplifier. Q3 and Q4 are for the regulator. My comment about the current limit on the zener still stands. circuit is from: http://www.aeroelectric.com/Pictures/Schematics/PM_Regulator/Kubota_Schematic.jpg
Yes, the circuit was dissected into two
functions at:
http://tinyurl.com/c8usyw2
http://tinyurl.com/c6doa97
. . . and you're right. The base-emitter junction of
Q4 in series with the hopefully small dynamic resistance
of the zener places the transistor at serious risk. This design
would not even come close to passing DO160 input voltage
tests. But then, not many garden tractors are subject
to the kinds of trash on the bus as airplanes.
I've not seen a schematic for a PM regulator that
offers warm-fuzzy feelings to an airplane jockey.
These bang-bang regulators have proven quite sufficient
for the lawn equipment markets and few folks have
complained about them in airplanes . . . at least
few to none here on the List. They may have a field
service history one step above dismal but not articulated
here.
If you're pondering a DIY project for a PM regulator,
consider adding some impedance in series with the
base of Q4. It doesn't need to be very big. The way
this thing is wired, the zener's operating current
is VERY low . . . a milliamp or less. Also poor design
practice . . . this is not up on the knee for predictable
conduction at the rated voltage. So 100 ohms in series
would protect the transistor and have very little
effect on regulation.
An adjustable regulator might modify the input circuit
to include a potentiometer which would add useful
base current protection for Q4. If you're up to brass-boarding
some experiments, I've had a few ideas for an upgrading
of the circuit's performance.
Bob . . .
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nuckolls.bob(at)aeroelect
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| Posted: Mon Oct 21, 2013 11:28 am Post subject: Jabiru 2200 voltage regulator again |
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At 08:54 AM 10/21/2013, you wrote:
| Quote: |
I know a number of us would like to improve the Rotax regs...
Please continue! Thanks.
|
Okay. The attached schematic is for a voltage regulator
(I'd leave that semi-worthless alt failure warn out).
Design goals:
Adjustable voltage regulation set point.
Improved thermal management
Tolerance to DO-160 abnormal voltage inputs
This would perform no better than the stock Rotax-
Ducati regulator except for design goals stated.
The second schematic deletes two transistors.
A first pass at the LM431 specs suggests that
the two extra stages of gain may not be
necessary.
A couple of experiments worth exploring . . .
Bob . . .
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| Description: |
|
Download |
| Filename: |
PM_Regulator_2.pdf |
| Filesize: |
124.21 KB |
| Downloaded: |
230 Time(s) |
| Description: |
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Download |
| Filename: |
PM_Regulator.pdf |
| Filesize: |
131.66 KB |
| Downloaded: |
202 Time(s) |
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uuccio(at)gmail.com
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| Posted: Mon Oct 21, 2013 11:14 pm Post subject: Jabiru 2200 voltage regulator again |
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| Quote: | This would perform no better than the stock Rotax-
Ducati regulator except for design goals stated.
|
Bob,
Assume you mean "no worse" in the sentence above 
Would you recommend switching out a Ducati regulator that's already installed (Kitfox, Rotax 912, VFR Only)?
Sacha
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a.s.elliott(at)cox.net
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| Posted: Tue Oct 22, 2013 6:49 am Post subject: Jabiru 2200 voltage regulator again |
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Just some additional options – I am running an 18A John Deere PM alternator in my plane and am using an aftermarket voltage regulator designed for Harley. Nearly all motorcycles use PM alternators, and these days cycles have all the fancy electronics like a plane or car. Plus the regulators are designed to survive in a very hostile environment. There are a number of good brands out there, including Accel, Crane, Compu-Fire, Cycle Electric and others. (Of course, there are also low-quality Chinese knock-offs, so buyer beware!)
My Crane Cams “Fireball” regulator is mounted behind the firewall, directly on the metal side skin, so it can use some of that that as additional cooling surface. The regulator runs through the B&C PM/OV Filter & Protection kit (504-1). I have about 5 years and 550 hours on the plane, mostly in the Arizona desert, with no problems at all in the electrical system, FWIW.
Andy
------------------------
Andy Elliott, CL:480-695-9568
N601GE/Z601XL/TD/Corvair
525 hrs since 11/08
Web Site Link
[quote][b]
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nuckolls.bob(at)aeroelect
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| Posted: Tue Oct 22, 2013 7:03 am Post subject: Jabiru 2200 voltage regulator again |
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At 02:13 AM 10/22/2013, you wrote:
> This would perform no better than the stock Rotax-
> Ducati regulator except for design goals stated.
Bob,
Assume you mean "no worse" in the sentence above
Either. The modification will leave regulator
performance unchanged. But utility is improved
with adjustability and reliability is probably
improved by more robust management of BTUs and
abnormal bus voltages.
Would you recommend switching out a Ducati regulator that's already
installed (Kitfox, Rotax 912, VFR Only)?
I don't think so. It's sorta like that discussion
we've had on el-cheapo contactors. The over all
service life, cost of ownership and risk should drive
the decision.
At Beech, there were issues that rose to the top-ten
list of field service issues. Those got red-team
attention. Then there were things that generated
ADs against the airplane. Those were tiger-team
tasks. Stuff that didn't make the top ten were
subject to economic triage and generally handled
by competent and courteous field service reps.
Many airplanes are flying this rectifier/regulator
. . . the failure rate has bubbled up to at least
nuisance levels for some individuals but perhaps
not enough for red-team response by Rotax, Jariru,
et. als. For some flyers of engines with PM
alternators, it may be sufficient incentive for a
re-invention this particular wheel. It's one of
those self-interested, free-market exchange of
value decisions. I don't see it as much of a risk
issue.
Bob . . .
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cffd66(at)yahoo.com
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| Posted: Tue Oct 22, 2013 7:20 am Post subject: Jabiru 2200 voltage regulator again |
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Bob,
Sorry for my ignorance, but how do I see your attachment?
Chuck D.
Time: 12:28:49 PM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>
Subject: Re: Jabiru 2200 voltage regulator again
At 08:54 AM 10/21/2013, you wrote:
| Quote: |
I know a number of us would like to improve the Rotax regs...
Please continue! Thanks.
|
Okay. The attached schematic is for a voltage regulator
(I'd leave that semi-worthless alt failure warn out).
[quote][b]
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