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Ceengland
Joined: 11 Oct 2020
Posts: 393
Location: MS
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 Posted: Thu Oct 20, 2022 3:50 pm Post subject: 'Homebuilt' voltage regulator to replace old unsafetied reg |
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On 10/20/2022 4:16 PM, Charlie England wrote:
| Quote: |
<ceengland7(at)gmail.com>
Just saw this article about the L9918 alternator regulator from ST
Microelectronics. I'm curious about whether it might be viable as a
replacement for the unprotected regulators still found in some of the
older 'one wire' alternators many of us still use, or perhaps, even
for an externally regulated alternator.
It has a lot of sophisticated features we'd likely never use, but a
quick stroll through the data sheet (link in the article) makes it
sound as if it will function just fine in standalone mode. Five
terminal device, but the 5th terminal is basically a 'comm' terminal,
which the data sheet implies can be lost and the regulator will still
function properly. It does have OV & UV protection built in. At a
onesies cost of <$10, it certainly looks tempting to try.
Charlie
Well shucks. For some reason, the link didn't 'take'. Here's the full link:
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https://www.electronicdesign.com/markets/automotive/article/21252965/electronic-design-automotivealternator-regulator-embeds-advanced-functionality-lin-interface?utm_source=EG+ED+Analog+%26+Power+Source&utm_medium=email&utm_campaign=CPS221013058&o_eid=0371F5910123I6U&rdx.ident[pull]=omeda|0371F5910123I6U&oly_enc_id=0371F5910123I6U
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bob.verwey(at)gmail.com
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| Posted: Fri Oct 21, 2022 2:39 am Post subject: 'Homebuilt' voltage regulator to replace old unsafetied reg |
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Actually looks amazing Charlie!
I am rebuilding a Luscombe at the moment and its" engine time" so I will be watching this space.
On Fri, 21 Oct 2022 at 01:52, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
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Best Regards,Bob Verwey
082 331 2727
[img]https://docs.google.com/uc?export=download&id=0B5d7rgAInTuTUUZsUjY4QmJsdVU&revid=0B5d7rgAInTuTdDJDaXRFZVh3b3lMa3FWL0s3MFdzc01YRlNvPQ[/img]
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Ceengland
Joined: 11 Oct 2020
Posts: 393
Location: MS
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| Posted: Fri Oct 21, 2022 4:27 pm Post subject: 'Homebuilt' voltage regulator to replace old unsafetied reg |
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On 10/21/2022 11:52 AM, Robert L. Nuckolls, III wrote:
| Quote: | | Quote: | | Quote: | | Just saw this article about the L9918 alternator regulator from ST Microelectronics. I'm curious about whether it might be viable as a replacement for the unprotected regulators still found in some of the older 'one wire' alternators many of us still use, or perhaps, even for an externally regulated alternator. |
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You're correct but with a couple of factors unique
to our applications:
I looked at the ancestors for this device while
still at Electro-Mech, circa 1980. The functional
'stumbling' block was feature called 'phase sample'.
The chip needs manage field excitation and shut
it down if the alternator is not rotating.
When the vehicle has systematic control over
field excitation (like an alternator field switch),
field current is shut off externally. In a one-wire
alternator, some internal means for field excitation
management is needed. The two diagrams I've attached
show the connector to one phase of the stator winding
where presence of an AC voltage annunciates alternator
rotation.
Early alternators utilized the
AUX terminal driving the "S" terminal (field
excitation relay) in the alternator to effect
field control.
One wire alternators would generally be discourage
under legacy aircraft system design rules calling
for absolute pilot control of all power sources.
Automatic spool up of an alternator based on
engine operation would not have been certifiable
. . . at least during my tenure in the business.
Additionally, emergency warning and automatic
reaction systems (of which OV is one such
system) had to completely independent of the
device over which they had authority. Combining
both control and ov shutdown onto a single chip
of silicon would not have been certifiable.
For example, I did a pitch system controller
for LearJets way back when. While the controller
and over-speed warning systems were in the same
enclosure BUT wiring, functionality and physical separation
of the two features had to be demonstrated.
Bob . . .
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Thanks, Bob; very educational.
I saw the 'PH' terminal, but in my quick stroll through the pdf I didn't really pick up on what it was used for. I did do a little googling for 'traditional' IR alternator regulators, & saw the same terminal being used in them. That's what got me thinking using it as a substitute.
I do understand the reasoning about having OV protection handled by an independent circuit. Having said that... I'm wondering about whether improvements in 'modern tech' with its much higher reliability might allow us to modify the philosophy a bit. I don't follow the automotive industry closely, but I don't recall hearing about an OV event in a car for a very long time.
Since the B+ terminal powering the regulator is available to us, it would seem that we could handle the overall control of the regulator by powering that terminal via our field breaker (which, if desired, would allow implementing separate OV protection). (Bringing regulator's power terminal out to a 'field' CB is a relatively common mod used in homebuilts that run IR alternators.) I'm speculating on the possibility to use this device (or something similar) for either internal mounting, or perhaps better, remote mounting just like a traditional external regulator.
Is this water too deep for wading, or might it be worth getting our feet wet?
Thanks,
Charlie
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