Today's Message Index:
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1. 08:30 AM - Re: Acceptable to use thin non aircraft wire to coil of re... (Dave N6030X)
2. 05:29 PM - automotive alternator question - OT (Bill Boyd)
3. 08:39 PM - Re: automotive alternator question - OT (Ernest Christley)
Message 1
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| Subject: | Re: Acceptable to use thin non aircraft wire to |
coil of re...
--> AeroElectric-List message posted by: Dave N6030X <N6030X@DaveMorris.com>
Not just "does it support combustion", but what gasses does it give
off, and will they kill you dead if you smoke one of the wires due to
a short somewhere?
Dave Morris
At 07:22 PM 10/19/2006, you wrote:
>--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
>
>Hello Barry,
>
>You might have noticed that Ron was asking about controlling the coil of a
>relay with this lightweight wire. The current required for such a task is
>likely less than 100mA.. VERY fine wire will handle that much current.
>If adequate electrical protection for the wire is provided, there's not
>much risk. Running this wire near the headset/mic wiring also probably
>won't be much of an issue. Very little current will pass through the
>control leads to a relay, so very little noise will be generated. The
>items on your list wouldn't be switched at high frequency either, so that
>helps too.
>
>Conversely, if you run heavy enough wire to power the strobes up the
>switch panel, and the wire is in the same bundle as the mic leads, I think
>that might invite headaches.. The other items on the list aren't likely
>to be a concern.
>
>I'd say that for the non-critical stuff that Ron listed (all of it), the
>most difficult issue is whether he can handle the mechanical end of the
>installation.. It can be a real bear to find connectors that work well
>with the extremely fine insulated wire. It can also be difficult to
>provide adequate strain relief for such wire. As you mentioned, Barry,
>abrasion resistance can be tough to address. For a small bundle of wire,
>I wouldn't be concerned about smoke factor either. I mean, it's a plastic
>airplane..
>
>The other issue I'd mention is parts count. Several more wire connections
>to make. Most common relays have moving parts and electrical contacts.
>Any of these items can fail. For non-critical systems, it's not a big
>deal safety-wise, but it will eventually lead to a higher hassle factor.
>It would look pretty cool though.. :)
>
>One final thought.. It might be tough to find test data for the proposed
>fine wire.. But you can generate your own.. Burn some. Does it support
>combustion? How easy is it to damage the insulation by abrasion?
>
>
>Regards,
>
>Matt-
>
>
> > In a message dated 10/19/2006 1:31:39 PM Eastern Standard Time,
> > rparigor@SUFFOLK.LIB.NY.US writes:
> > My partner has access to wire that is bout as thick as a model airplane
>servo wire. They come in twisted pairs, from 3 pairs on up. It is
>probably
> > like the twisted wires you see inside computers, like the ones running
>fans etc.
> >
> > These wires would be running along side of headphone/mic wiring.
> >
> > Does this sound acceptable?
> >
> > Ron Parigoris
> > ==============================
> > Ron:
> >
> > I would say NO.
> >
> > The reasons are:
> > 1 - Cannot handle the current.
> > Even if the aircraft wire and your wire are the same gage the insulation
>cannot handle the current.
> >
> > 2 - Abrasion - Aircraft wire has a high resistance to abrasion.
> > The thin stuff (R/C Servo wire) cannot handle it.
> >
> > 3 - Flammability - The wire you want to use does not meet flammability
>requirements.
> > It probably does not meet the fume requirements either.
> >
> > 4 - I know, I know - you are thinking experimental.
> > Still not a reason to misplace good building practices or AC 43.13 2B
> >
> > 5 - Back to item #1 --- Cannot handle the current.
> > The R/C servo wire is about 22 AWG. It is in short runs. And has next
>to
> > zero current ... Miliamps!
> > Your position lights are probably in the area of 2 Amps Each ... And you
>have
> > three, so you are looking at about 6 Amps.
> >
> >
> >
> > Barry
> > "Chop'd Liver"
> >
> > "Show them the first time, correct them the second time, kick them the
>third
> > time."
> > Yamashiada
> >
>
>
Message 2
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| Subject: | automotive alternator question - OT |
--> AeroElectric-List message posted by: "Bill Boyd" <sportav8r@gmail.com>
Just when I thought I knew a little something from building airplanes
and hanging out here for five years or so...
Yesterday my wife was driving my son's 99 Hyundai when warning lights
began to appear one by one- battery, emergency brake, air bag; then
the speedometer and tach indications went to zero, and finally the
engine itself quit running. She phoned me at the office, and I told
her that she had just described a classic alternator failure with
subsequent run-down of the remaining energy in the battery. We
confirmed that the alternator belt had not broken, but there was
little to do but call for help. Help arrived, gave her a jump start;
she was able to drive part way to the repair shop when the same
sequence repeated itself. The second jump start got her the rest of
the way to the repair bay.
We called today, expecting the bill to be large, but it was under
$100. When I got there to talk to the mechanic, I told him I had
expected an alternator replacement to be part of the plan. He assured
me that only the battery was faulty, and that the alternator was
"putting out 14.3" so all was well. I asked how the car could die
electrically when the engine was running, and he gave me a sympathetic
look and began to explain how generators put out direct current, but
the new-fangled alternators put out _alternating current_ and they
need a battery to keep them excited. I pretended to take it all in
and thanked him, paid the bill, and told the wife to ride home close
behind me, because with an ailing alternator, I likely had only the
joules in the battery to make the half-hour trip in the dark. I did
my best to keep the electrical loads light, as if running on the e-bus
in the scud ;-)
To my surprise, the alternator indeed seems to be charging normally,
and the new battery installation seems to have mysteriously fixed
things.
Now, I know there is no way that a battery continually feeds current
into an alternator to keep it going, else charging the battery from
the alternator would be a losing proposition. And I certianly hope
that there is no way a dead battery is going to somehow take out my
dual alternator Z-13/8 architecture, but I cannot reconcile that hope
with what seems to have happened to my car electrical system here.
Tell me I'm not crazy, and that it doesn't take a battery to keep an
alternator alive once excited (the same battery that minutes before
cranked the engine for starting), that the battery is only there for
filtering the 3-phase rectified DC when in cruise mode, and I'll
believe you. But I'll still wonder what happened to the car
yesterday...
-Bill B
Message 3
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| Subject: | Re: automotive alternator question - OT |
--> AeroElectric-List message posted by: Ernest Christley <echristley@nc.rr.com>
Bill Boyd wrote:
> But I'll still wonder what happened to the car
> yesterday...
>
Bill, does the alternators B-lead connect at the battery post? I may be
very wrong, but I seem to recall an old Nissan truck I owned being wired
that way. If it is the case, a dirty battery cable termination would
give exactly the symptoms you describe, and would be cured by replacing
the battery (the connector gets jostled around, knocking out the
corrosion long enough to make it home).
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