Today's Message Index:
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1. 08:27 AM - Re: Fuse rating on AWG 20 wire with AeroLED strobes? (Robert L. Nuckolls, III)
2. 01:35 PM - Re: Fuse rating on AWG 20 wire with AeroLED strobes? (zwakie)
3. 02:28 PM - Re: Re: Garmin 335 Transponder Installation Manual (Alec Myers)
4. 02:35 PM - Re: Stall warning through Radio (user9253)
5. 02:52 PM - Re: Re: Stall warning through Radio (Robert L. Nuckolls, III)
Message 1
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Subject: | Re: Fuse rating on AWG 20 wire with AeroLED strobes? |
At 10:40 PM 12/2/2018, you wrote:
>When you say 'unlike circuit breakers'...what do you mean? Would
>the CB trip more quickly than a fuse would blow, or would it be more
>tolerant of what you're calling 'hammering'?
Both devices operated based on temperature
rise caused by current generated heating.
Breakers are bi-metal 'thermostats' . . . they
trip at a calibrated temperature which is
NOT affected by previous excursions up to the
edge of tripping. A CB is good for thousands
of trip cycles with very little change in
performance.
Fuses are pieces of metal designed to heat up
and melt at a predictable temperature. A
characteristic that can be tailored to a
current flow through the 'sensing' metal.
But operating a fuse at its recommended
'limit' (75% of rating) produces SOME
heating. This means that a fuse under
normal load is already some way up the
I(squared)R trip ladder when it is presented
with transient 'overloads'. These little pushes
into trip territory can cause mini-melts to
occur in the fusible material which has the
effect of lowering the fuse's rating. Repeated
'hammering' will seriously compromise predictability
of that fuse to carry normal loads.
When N811HB lost both ignition systems on
base to the runway, the single fuse carrying
BOTH ignition systems had been loaded to
more than 75% on several occasions with
short excursions to over 100%. Compromised
fuse predictability combined with poor
choices in architecture to kill the
engine.
>And your last statement 'there are no risks associated with
>up-sizing the 20 AWG protection to the next level', do you mean
>using a 10A fuse with 20 AWG, or are you saying to increase wire gauge to 18?
'20AWG protection' is classically pegged
at 7A. Raising it to 10A or even 15A
in this situation will stand off the 'hammering'
effects. It is not a risky thing to do. It
will eliminate the possibility of nuisance
tripping.
Given that the lights do not represent a
critical flight system, you could leave the
7A fuse in place and see how it goes. If
you experience a nuisance trip, up-size the
fuse.
Let us know what you discover . . .
Bob . . .
Message 2
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Subject: | Re: Fuse rating on AWG 20 wire with AeroLED strobes? |
I did a little experiment on Saturday after having finalized the wiring on my strobes.
Specs ask for 5A fuse, so I put a 5A fuse in and lighted up the strobes.
Having read this post on Friday night, I was expecting the fuse to blow, but I
was very surprised to see that happen so quickly (literally well within 10 seconds).
A 7.5A fuse did hold while keeping the strobes on for more than 2-3 minutes, but
to be safe I 'upped' the fuse to 10A and will 'up' the two short leads from
fuse block to switch to the beefy wiring that a previous owner has put in to match
the 10A fuse. I will also review the determined fuse-sizes for other circuits
that (can possibly) carry transient loads.
This was an educational experiment.... ;)
--------
Marcel Zwakenberg
Europa XS TG || 912ULS || PH-SBR
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=486118#486118
Message 3
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Subject: | Re: Garmin 335 Transponder Installation Manual |
I have a bunch of service manuals is there somewhere I can upload them for Bob?
On Dec 2, 2018, at 1:45 PM, Robert L. Nuckolls, III <nuckolls.bob@aeroelectric.com>
wrote:
At 06:42 AM 12/2/2018, you wrote:
>
> I just wanted to say thank you to a number of people who privately
> sent me a variety of documents that will be extremely helpful
> installing a Garmin 335 transponder.
>
> This list is a great resource for any required information !!
>
> Thanks !
>
> Jeff Page
> Dream Aircraft Tundra #10
>
> Do not archive
If persons in possession of such data would
like to have it added to the archives on
aeroelectric.com I would be pleased to
receive them also . . .
Bob . . .
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Subject: | Re: Stall warning through Radio |
There are lots of ways to make an alarm tone.
The Forrest Mims Engineer's Notebook (my favorite book) has some circuits.
https://www.zpag.net/Electroniques/Kit/The%20Forrest%20Mims%20Engineers%20Notebook.pdf
On page 55 is a gated tone source. Grounding a pin on a 74LS368 turns on the tone.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=486120#486120
Message 5
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Subject: | Re: Stall warning through Radio |
At 04:35 PM 12/3/2018, you wrote:
>
>There are lots of ways to make an alarm tone.
>The Forrest Mims Engineer's Notebook (my favorite book) has some circuits.
>https://www.zpag.net/Electroniques/Kit/The%20Forrest%20Mims%20Engineers%20Notebook.pdf
>On page 55 is a gated tone source. Grounding a pin on a 74LS368
>turns on the tone.
Boy . . . there's a classic. I've recommended
that publication dozens of times over the years.
An excellent learning tool.
Bob . . .
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