Today's Message Index:
----------------------
1. 09:56 AM - Re: Re: Time delay on relay needed (Robert L. Nuckolls, III)
2. 10:05 AM - Re: Dual Battery Setup (Robert L. Nuckolls, III)
3. 10:58 PM - Re: Integration of Rotax 912iS (Jeff Page)
Message 1
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| Subject: | Re: Time delay on relay needed |
>Bob:
>The Buzzer is an electro mechanical:
>https://www.amazon.com/gp/product/B000XBJ3AE/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
>The Arduino is powered by a 12 volt battery going through a
>converter to make 5 volts for the Arduino. The buzzer is using the
>12 volts to operate. We put it on a scope today and saw
>perturbations of the 5 volts peak to peak of between 10 and 12 volts.
>We added transorbs and .1 mF ceramic capacitors across the two
>parallel buzzers and also a .1 mF ceramic capacitor just before the
>DC to DC converter. Got peak to peak down to 5 to 6 volts. So far it
>seems to be working OK.
>
>Ron P.
That style of buzzer is one of many examples
of the classic 'model-T spark coil' physics. What
you're experiencing is conducted noise in the form
of fast-rise time transients generated every
time the points in the buzzer break. This can be
a very 'potent' noise source for some situations.
In fact, legacy DO160 qualification testing used
to include what was commonly called a 'chattering
relay' noise test illustrated here. The "timer"
switch was simply the normally closed contacts
of the test fixture relay, I.e. a 'buzzer'.
The Model-T spark coil was another 'buzzer' where
the buzzer coil shared a core with a bazillion
turns of fine wire where one could exploit very
high voltage transients that would jump the
gap in a spark plug.
A modern exploitation of the same phenomenon
is illustrated in a 'shower of sparks' starting
ignition for an M14 radial engine I crafted for
a YAK driver.
So, getting back you your close encounter of
the unhappy kind, your potential victim is a
micro-controller that runs on 3.3 volts DC.
It doesn't take much of a transient to express
itself as aberrant noise. Data in the uC
lives in a 3 volt, tens of megaHertz world
exceedingly vulnerable to fast rise
transients.
As you've already discovered, suppression of
the buzzer's coil collapse transient mitigates
the problem. If you have access to the buzzer's
coil terminals, it would be interesting to see
if a simple suppression diode would stop the
problem. If not, then some network of external
components is indicated to reduce this potent
noise source from irritating your microcontroller.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 2
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| Subject: | Re: Dual Battery Setup |
At 06:58 PM 10/10/2022, you wrote:
>I am new to this list, but was told to come here
>for advice on my electrical=C2 design for a fuel
>injected, electronic ignition single engine
>plane. I have looked at AeroElectric design
>recommendations but wanted to hear feedback on the following changes ...
Your battery and fuel pump controls argue with
'redundant'. Both switch arrays offer single
points of failure for both systems.
'Redundant' generally implies TOTAL separation.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 3
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| Subject: | Re: Integration of Rotax 912iS |
> Hi Eric,
>
> I am not familiar with a Rotax installation, so some of my comments may
> not apply.
> Here are some things to review:
>
> 1) There is a 22AWG powering the endurance bus feed relay coil, direct
> from the battery, but not marked *. Perhaps add a fuse?
> 2) There does not appear to be a power feed to the relay coil of the
> airframe bus feed relay.
> 3) Perhaps add an indication of the start relay engaged, in case it
> sticks?
> 4) Perhaps add a 15A fuse at the battery bus to the endurance bus feed
> (14AWG not marked with *).
>
> 5) Perhaps add a 15A fuse at the battery bus to the airframe bus feed
> (14AWG not marked with *).
> 6) I didn't find the backup battery anywhere, but perhaps it is fed
> from the Rotax fuse box?
> 7) I dislike inline fuses. There are two inline 1A fuses. Why not make
> just include them in the fuse box for the battery bus?
>
> Nicely done diagram. Easy to follow with lots of good notes.
>
> Jeff Page
> Dream Aircraft Tundra #10
>
> ________________________________ Message 3
> _____________________________________
>
> Time: 12:17:02 PM PST US
> Subject: AeroElectric-List: Re: Integration of Rotax 912iS
> From: "Eric Page" <edpav8r@yahoo.com>
>
> Reviving this thread from a year ago:
> http://forum.matronics.com/viewtopic.php?t=16777418
>
> I've fleshed out my electrical system architecture diagram and would
> appreciate
> another round of checks by the group.
>
> Changes since my simplified diagram was posted last year:
> - Renamed Main Bus to Airframe Bus.
> - Eliminated the complicated module to switch power to the Airframe
> Bus, in favor
> of a simple relay-and-switch arrangement.
> - Added an Endurance Bus with dual feed paths.
> - Added an Overvoltage Protection Module in the path from the Rotax
> Fuse Box X3
> Pin 3 to the Battery Bus.
> - Developed wiring diagrams for the Airframe and Endurance Buses.
>
> In addition to any problems you find, I have two specific questions:
> 1. The Rotax 912iS Installation Manual specifies 30A fuses at the
> Battery Bus,
> for the 12AWG wires to the Backup Battery Switch and the Fuse Box X3
> Pin 3. Can/should
> 16AWG fusible links be used instead?
> 2. Is my use of fusible links acceptable for the Endurance & Airframe
> Bus feeders
> at the Battery Bus and the hot side of the Battery Contactor?
>
> Related links:
> Previous simplified diagram:
> http://forum.matronics.com/download.php?id=48574
> Rotax 912iS wiring diagram:
> http://forum.matronics.com/download.php?id=48575
> LTC1696 data sheet:
> https://www.analog.com/media/en/technical-documentation/data-sheets/1696fb.pdf
>
> Thanks!
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=508051#508051
>
> Attachments:
>
> http://forums.matronics.com//files/overvoltage_protection_relay_module_rev_b_221.pdf
> http://forums.matronics.com//files/electrical_architecture__kitfox_5__rotax_912is_171.pdf
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