Today's Message Index:
----------------------
1. 06:42 AM - Re: SAE documentation question (Eric M. Jones)
2. 06:50 PM - wiring diagram-sperry (Christopher Stone)
3. 08:59 PM - Re: SD-8 PM Alternator (J. Mcculley)
4. 09:23 PM - Re: SD-8 PM Alternator (Ron Shannon)
Message 1
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Subject: | Re: SAE documentation question |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
Usually your local librarian can get SAE docs and DO-160 docs and all sort of amazing
stuff (the'll even do business by email. Your tax dollars at work. Your
local copy shop will be happy to make a copy for you. Don't forget to point out
to them that this is a copyright violation. Ahem...
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=33123#33123
Message 2
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Subject: | wiring diagram-sperry |
--> AeroElectric-List message posted by: Christopher Stone <rv8iator@earthlink.net>
Hello all...
I am hoping that someone might have or know where I might find a pinout diagram
for a Sperry IN-381A converter indicator head (GS/LOC/VOR).
I have struckout with the major avioncs sellers.
Thanks,
Chris Stone
Newberg, OR
Message 3
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Subject: | Re: SD-8 PM Alternator |
--> AeroElectric-List message posted by: "J. Mcculley" <mcculleyja@starpower.net>
'Lectric Bob,
On 4/22/06, you responded to my earlier report of a way to assure
bringing the SD-8 PM alternator on line without benefit of a battery
source of excitation. My finding that as little as one volt charge on a
capacitor was adequate to awaken the SD-8 apparently suggested to you
that there might be an even simpler way to modify the SD-8 regulator to
accomplish independence of the PM alternator from a battery source of
start-up voltage. Your proposed design was as follows:
(SNIP)Your experiments have shown that the regulator will come alive
> with a very low voltage available at the 'b-lead'. A study
> of the schematic for the Kubota regulator leads one to
> conclude that once you have just enough voltage to forward
> bias some junctions (The b-e junction of Q3 through R3
> and D6) there is a potential for triggering the SCRs and
> having the system wake up. I suspect the B&C regulator
> is similar.
>
I thought of another approach to suggest. Since you're set up for
and have the mind-set to conduct the necessary experiments,please
consider . . .
>
> http://www.aeroelectric.com/Pictures/Schematics/PM_Regulator/Self_Excitation_Experiment.jpg
>
> What we'd like to do is not let the b-lead voltage out
> of the regulator be 100% dependent upon triggered SCRs in
> the regulator. Suppose you added a couple of diodes
> from the alternator winding along with a resistor to
> ground to build a very inefficient keep-alive rectifier.
> The two diodes parallel the SCRs but with a conduction
> impedance too high for the system to deliver significant
> power. We then need some small, fixed 'load' across the
> output filter capacitor to prevent the unloaded alternator
> voltage (as high as 40v) from charging the capacitor
> to a level dangerous to the cap and system equipment
> in case the alternator control relay is closed while the
> capacitor is charged up.
>
> I've shown a pair of 1K resistors. Use mechanically
> hefty resistors . . . the 2W isn't need for electrical
> reasons, just mechanical. Adjust the size of the series
> resistor at the diodes to achieve a couple of volts or
> more (but not greater than 14) across the capacitor
> at max engine rpm with the alternator system OFF.
> I suspect this resistor might be as high as 3 to 10K
> and still make the system sleep with one eye open.
> Here, we have an opportunity to go a step further
> and modify the regulator's performance such that
> it never quite goes to sleep and eliminate the
> need for pilot intervention to kick-start the
> system. If you can assist in conduction of this
> experiment, we can prove/disprove my hypothesis
> and perhaps generate an article that will help
> others slay this dragon too.
> Bob . . . (SNIP)
I am happy to report that I implemented your concept and conducted
successful ground testing today of the SD-8 installation on my Lycoming
180 HP Tailwind.
In order to achieve the desired range of voltage across the capacitor
when BOTH the alternator is OFF LINE and the MASTER switch is OFF, I
found it necessary to increase the suggested 10k ohm resistor from
ground to the pair of diodes to a value of 15k, and to increase the 1k
ohm resistor across the capacitor to 3k ohm.
In this configuration, the voltage across the capacitor slowly rises to
0.6 volts within a 3 minute period after engine start while warming up
at 1100 Engine RPM (1430 alternator RPM). This is insufficient to bring
the alternator on line if the Alternator switch is then turned on.
However, as the engine RPM is advanced to the range of 1700-1800 for mag
check, the alternator is now at 2210-2340 RPM with capacitor voltage
slightly above 0.6 v and if the alternator switch is now turned on the
alternator comes alive to produce an unloaded buss voltage of slightly
over 12 V. This unloaded buss voltage continues to rise with RPM to a
maximum of 14.42 V at engine rated 2700 RPM (alternator at 3510 RPM). As
buss load is added, the regulator maintains 14.29 V until enough load is
added to begin dropping the voltage in keeping with the alternator
design current limits. With the Master switch still OFF, the buss
voltage responds to the electrical load versus RPM in a predictable
manner. Even if the RPM/load combination is carried to an extreme that
produces buss voltage down to as little as 5 V, the alternator stays
activated and comes back up in voltage to no higher than 14.42 if the
load/RPM combination is re-adjusted.
I suspect the system would respond differently with a smaller capacitor
than the 56K mf unit that I adapted from my previous set-up, but I did
not observe any undesirable features, and at this preliminary stage I
believe the overall concept produces a fully automatic solution to
eliminate the fear that a PM alternator could fail to come on line in
the absence of a voltage source such as the ship's battery.
Please recognize that the above data during operation of the SD-8 just
after engine start-up is not the condition of interest in normal
operation. The engine (and alternator) would more likely be at higher
RPM during cruise flight when the buss voltage might be lost while the
SD-8 is not on line. In this situation,the alternator RPM and available
voltage across the capacitor would already be high enough to immediately
bring the alternator on line by simply turning the alternator switch on.
I will soon verify this on an upcoming flight.
Jim McCulley
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Subject: | Re: SD-8 PM Alternator |
--> AeroElectric-List message posted by: Ron Shannon <rshannon@cruzcom.com>
Jim,
Thanks for the report on your excellent work! Am looking forward to
further chapters in this story, as your time permits.
Ron
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