Today's Message Index:
----------------------
1. 12:09 AM - Re: Engine start button (John Tipton)
2. 06:16 AM - Re: Engine start button (user9253)
3. 06:28 AM - Re: Engine start button (Robert L. Nuckolls, III)
4. 06:41 AM - Re: Engine start button (John Tipton)
5. 08:02 AM - Re: Engine start button (Dennis A Glaeser)
6. 09:20 AM - Re: Re: Dimmers driving displays... (Robert L. Nuckolls, III)
7. 11:03 AM - Shutting an Alternator off (Justin Jones)
8. 11:26 AM - Re: Shutting an Alternator off (Robert L. Nuckolls, III)
9. 02:43 PM - Re: Engine start button (Peter Pengilly)
Message 1
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| Subject: | Re: Engine start button |
But why wouldn't it, if the light weight (Lilliputian) switch has it's own relay,
should that not be enough for the circuit (Z11 etc: 20awg 7amps) to a starter
contactor, as Peter cited he has used similar for a few years now.
John
Sent from my iPad
----x--O--x----
> On 6 Apr 2015, at 08:32 pm, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
wrote:
>
>
> At 08:58 2015-04-06, you wrote:
> Hi Guys
>
> I'm thinking of using this 'engine start' button (only the button, from the panel
shown) on the RV9 - it looks more than a simple 'push to close' wiring, am
I still good to go with this item
>
> Best regards
>
> John'
>
> It appears that this kit comes with a relay
> for boosting the current handling ability
> of the rather Lilliputian switch. The same
> relay would be recommended for the switch
> that Peter has cited. Neither device would
> stand up robustly to switching loads imposed
> by intermittent duty starter contactors.
>
>
>
>
> Bob . . .
>
>
>
>
Message 2
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| Subject: | Re: Engine start button |
My RV-12 starter contactor-coil circuit is protected by a 2 amp fuse.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=440364#440364
Message 3
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| Subject: | Re: Engine start button |
At 02:07 2015-04-07, you wrote:
But why wouldn't it, if the light weight (Lilliputian) switch has
it's own relay, should that not be enough for the circuit (Z11
etc: 20awg 7amps) to a starter contactor, as Peter cited he has used
similar for a few years now.
The kit cited had a plastic cube relay with fast-ons.
I assumed it was intended to be used to buffer the
starter contactor/solenoid current thus limiting
the push-button's stresses to the 150 mA or so
drawn by the relay coil.
Peter spoke to a 'regular starter relay' which does
not paint a lucid image in my peanut butter . . .but
let's assume it's a generic intermittent-duty contactor
with a coil current on the order of 5A and capable of
significant inductive reaction. If such a contactor
is fitted with coil suppression, then it is quite possible
that a switch of this genre' would stand up to the
task for hundreds of cycles, i.e. years in an airplane
flow on average 100 hours a year.
Without having specific ratings for Peter's switch,
I have to go with the 'feel' conjured up by the
image which suggests a switch probably rated at
1A or so for tens of thousands of cycles . . .
and indeed capable of the service that Peter
cited.
Emacs!
The other switch has a curious back side
with screw-clamps. This suggests more robustness
than the switch above . . . but again . . .
no data . . . no foundation for prediction.
Emacs!
Without having one of those kits in hand, we
don't know how the relay is to be used. I would
not expect it to be required in the ignition system
but who knows?
So understand that my assertions arose more
from rules of thumb and gut feelings with roots
in my design-for-lifetime-of-airplane in a
TC world than from any assessment of hard data.
Either switch may well produce satisfactory
service as control of a coil-suppressed starter
contactor.
Bob . . .
Message 4
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| Subject: | Re: Engine start button |
Bob
Thank you
John
Sent from my iPad
----x--O--x----
> On 7 Apr 2015, at 02:26 pm, "Robert L. Nuckolls, III" <nuckolls.bob@aeroel
ectric.com> wrote:
>
> At 02:07 2015-04-07, you wrote:
.com>
>
> But why wouldn't it, if the light weight (Lilliputian) switch has it's own
relay, should that not be enough for the circuit (Z11 etc: 20awg 7amps) to
a starter contactor, as Peter cited he has used similar for a few years now
.
>
>
> The kit cited had a plastic cube relay with fast-ons.
> I assumed it was intended to be used to buffer the
> starter contactor/solenoid current thus limiting
> the push-button's stresses to the 150 mA or so
> drawn by the relay coil.
>
> Peter spoke to a 'regular starter relay' which does
> not paint a lucid image in my peanut butter . . .but
> let's assume it's a generic intermittent-duty contactor
> with a coil current on the order of 5A and capable of
> significant inductive reaction. If such a contactor
> is fitted with coil suppression, then it is quite possible
> that a switch of this genre' would stand up to the
> task for hundreds of cycles, i.e. years in an airplane
> flow on average 100 hours a year.
>
> Without having specific ratings for Peter's switch,
> I have to go with the 'feel' conjured up by the
> image which suggests a switch probably rated at
> 1A or so for tens of thousands of cycles . . .
> and indeed capable of the service that Peter
> cited.
>
>
>
>
>
> <cc6129c.jpg>
>
> The other switch has a curious back side
> with screw-clamps. This suggests more robustness
> than the switch above . . . but again . . .
> no data . . . no foundation for prediction.
>
> <cc612ea.jpg>
>
> Without having one of those kits in hand, we
> don't know how the relay is to be used. I would
> not expect it to be required in the ignition system
> but who knows?
>
> So understand that my assertions arose more
> from rules of thumb and gut feelings with roots
> in my design-for-lifetime-of-airplane in a
> TC world than from any assessment of hard data.
>
> Either switch may well produce satisfactory
> service as control of a coil-suppressed starter
> contactor.
>
>
> Bob . . .
Message 5
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| Subject: | Re: Engine start button |
I have a large red "Engine Start" button from a sports car (Mazda I think,
but not sure anymore). The switch itself is a low load device, so it activ
ates a Bosch (cube) relay which actually powers the solenoid on the starter
. My engine is a Subaru, so all the automotive components are right at hom
e!
This system has been operating flawlessly for 7 years and 400 hours now.
I've attached a picture (during construction), not sure if it will come thr
ough...
Dennis Glaeser
RV7A
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Message 6
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| Subject: | Re: Dimmers driving displays... |
I spend a lot of time on the road these days . . . useful for
what I call "asphalt design time". Here's yet another option for
slaying Andy's dimming dragon . . .
Few pieces of silicon have enjoyed so long and rich a history
in electronics as the 555 timer. I remember seeing the data
sheets on this device from Signetics . . . a sales
rep dropped it off with several others at my first TC aviation
design job at Electro-Mech about 1975 . . .
I won't go into details of its features here but suffice it to
say that this device might fit into yet one more application that
Mr. Camenzind probably never imagined.
http://tinyurl.com/yb23fes
In the schematic below, we see how the 555's two comparators
biased at 1/3 and 2/3 of supply voltage can be used to provide
functional logic that goes to the task at hand.
Emacs!
Wired as shown, dimmer output voltage sample is applied
to the two comparators on pins 2 and 6. If the dimmer
output goes lower than 4v, pin 3 goes HI and turns
the two transistors ON thus applying full bus voltage
to the two instruments needing special attention. If the
dimmer output is cranked up to more than 8 volts, the
555 output goes LO and turns both transistors off. Under
this condition, dimmer output has control over the
displays on the two instruments. It remains in this
condition until dimmer output is dialed down below 4
volts whereupon, the 555 'flips' to the daytime
lighting condition.
This circuit could be spider-webbed into the back
shell of a D-sub connector . . . not unlike the
relay packaging project we discussed here on the List
last week.
Bob . . .
Message 7
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| Subject: | Shutting an Alternator off |
Some Maules have a placard in the aircraft that say not to shut the alternator
off in flight except in case of emergency. Any idea why this is so? Can shutting
an alternator down in fight cause damage to the electrical system?
Thanks
Justin
Message 8
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| Subject: | Re: Shutting an Alternator off |
At 12:58 2015-04-07, you wrote:
><jmjones2000@mindspring.com>
>
>Some Maules have a placard in the aircraft that say not to shut the
>alternator off in flight except in case of emergency. Any idea why
>this is so? Can shutting an alternator down in fight cause damage
>to the electrical system?
I've spent hundreds of hours in airplanes and on
test stands flipping switches and cranking knobs
on various combinations of engine driven power sources,
batteries and electrical loads. Not once have I
had any worries about turning the alternator on/off
while in operation.
Some years ago, a common aviation hangar-myth migrated
onto the List: "Turning an alternator on/off while
in service (1) subjects the alternator or engine drive
pads to deleterious stresses or (2) generates radio
killing transients on the bus."
This myth persists in many factions of the industry
including notions that (a) avionics master switches
erect a good and useful firewall against damage to
radios, (b) a dead battery paralleled with a charged
battery will discharge the good battery, (c) and
numerous others.
Bob . . .
Message 9
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| Subject: | Re: Engine start button |
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