Today's Message Index:
----------------------
1. 12:19 AM - Re: ELT Mounting Bracket (Speedy11@aol.com)
2. 05:11 AM - Re: Relay coils and diodes (Ralph E. Capen)
3. 06:03 AM - Re: Re: Switch problem (Robert L. Nuckolls, III)
4. 07:57 AM - Re: Re: ELT Mounting Bracket (Kyrilian Dyer)
5. 08:23 AM - Re: Scope (Robert L. Nuckolls, III)
6. 08:47 AM - Re: ELT Mounting Bracket (JohnInReno)
7. 10:14 AM - Re: Re: Scope (Ken)
8. 12:06 PM - What am I doing wrong? (Fergus Kyle)
9. 12:28 PM - Re: What am I doing wrong? (Sam Hoskins)
10. 12:29 PM - Re: What am I doing wrong? (Sam Hoskins)
11. 12:31 PM - Re: What am I doing wrong? (Ron Quillin)
12. 12:33 PM - Re: What am I doing wrong? (Ron Quillin)
13. 12:43 PM - Re: What am I doing wrong? (Neal George)
14. 12:49 PM - Re: What am I doing wrong? (Mickey Coggins)
15. 12:59 PM - Re: What am I doing wrong? (John Morgensen)
16. 12:59 PM - Re: What am I doing wrong? (Mike Pienaar)
17. 01:07 PM - Re: Re: Scope (Robert L. Nuckolls, III)
18. 01:16 PM - What did I do wrong? (Fergus Kyle)
19. 01:32 PM - Re: What am I doing wrong? (Vernon Little)
20. 02:23 PM - Re: Switch problem (Charles Brame)
21. 02:50 PM - Ammeter reading oddly (Neil Clayton)
22. 03:11 PM - Re: Ammeter reading oddly (Robert L. Nuckolls, III)
23. 04:16 PM - Re: What did I do wrong? (Ron Quillin)
24. 08:01 PM - Hangar Clean Out Day.... (Don Honabach)
Message 1
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| Subject: | Re: ELT Mounting Bracket |
Did you ask Ameri-King?
Stan
Do not archive
>Why does the mount for the Ameri-King ELT have a "wedge" under the
>rearward end so that the radio is tilted 20 up in the back?
Mount for a helo?
They're at an angle...
**************Psssst...Have you heard the news? There's a new fashion blog,
plus the latest fall trends and hair styles at StyleList.com.
(http://www.stylelist.com/trends?ncid=aolsty00050000000014)
Message 2
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| Subject: | Re: Relay coils and diodes |
Thanks Bob.....
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckolls.bob@cox.net>
Sent: Friday, September 05, 2008 6:14 PM
Subject: Re: AeroElectric-List: Relay coils and diodes
> <nuckolls.bob@cox.net>
>
> At 12:54 PM 9/5/2008 -0400, you wrote:
>><recapen@earthlink.net>
>>
>>My experience - shared for mine and other's education and offering of
>>opinion.
>>
>>This past weekend, I was working on the wiring of my flap position sensor
>>for my two-speed elevator trim circuit. The two-speed trim circuit
>>essentially switches a low speed set matronics governor for a high speed
>>set one via a pair of 4PDT relays whenever the flaps come off the upstop.
>>
>>As I was testing the detector switch - I got 'bit' by something that felt
>>like house current (done that too!). Not knowing what was going on, I
>>repeated the test...with identical results.
>
> Yeah, been there, done that. In my case I got the
> fingers across the contacts of a cub-scout electric
> buzzer project that operated from 3 volts (two flashlight
> cells). The field collapse from the small buzzer
> solenoid coil was sufficient to give ME a buzz which
> caused me to drop the project thus damaging it.
>
> Unfortunately it was not my project and my schoolmate was
> pretty unhappy about it. Neither of us understood what
> happened or why . . . but he got a personal demonstration
> of the effect a few days later. Even after my Navy veteran
> electrician father explained it to us, we didn't really
> understand.
>
>
>>OK, break out some of Bob's literary work - read-up and put in some diodes
>>across the power terminals of the coil.
>>
>>Re-reading made me think that in my case, the diodes may be even more
>>important...in Bob's writings (Paraphrased) "the absence of the diode
>>presents the opening switch with the spike"; in my case, I have a couple
>>of things wired up within the master switch... I'm thinking that in my
>>case the master switch would 'see' the spike...along with anything else
>>that is left on when I turn off the master.
>>
>>I know that the 'real' airplane stuff should be able to live in this
>>environment and should not produce this environment either - however in
>>the OBAM world, I can put in non tso'd trim servos and indicators (of
>>which I have had a couple of them mysteriously blow one of their indicator
>>lights) which are pretty good gear as far as I'm concerned - they just
>>haven't spent the money and gone through the certification process.
>>
>>Got the diodes and will be putting them in this weekend. Is it possible
>>that I'm allowing a spike to wander around my electrical system by turning
>>off the master with some of these relays energized?
>
> No. First, while the voltages generated by magnetic
> field collapse on a relay or contactor can be pretty
> spectacular, the ENERGY they contain is small. Given
> that the voltage is proportional to rate-of-magnetic
> decay, it stands to reason that maximum rate occurs at
> minimum current or widest opening of contacts on the
> controlling switch. This is a long winded way of stating
> that the source impedance of the relay coil as an energy
> storage device is big . . . too big to propagate significant
> pulses of "spike" energy out onto the bus.
>
> Most accessories have some amount of capacitance right
> across the power input leads as filters. This capacitance
> alone is a huge energy sink to inductively stored spikes.
> Risks to anything other than the controlling switch due
> to magnetic field collapse has been greatly exaggerated
> and poorly understood.
>
> There is no reason to be concerned beyond the effects
> on the controlling device . . . even if the diodes are
> not present.
>
> Bob . . .
>
>
>
Message 3
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| Subject: | Re: RE: Switch problem |
At 10:35 PM 9/5/2008 -0700, you wrote:
>Bob:
>
>Thank you for your analysis. I would have been happy to send you the
>offending switch, but I have already dismantled it in order to satisfy my
>curiosity. The only real visual sign was some arc pitting on the contact
>surfaces. I believe that over time this pitting caused a high resistance
>that did two things. First, there was a voltage drop across this
>resistance which in series with the strobe unit caused the unit to stop
>working because of reduced voltage. When that happened I shut the circuit
>off and did not use it anymore. Second, the resistance at the pitted
>contacts generated enough heat to discolor the blue insulation on the
>Fast-On connectors, but I caught it before any further heat damage
>occurred. The switch components looked normal except for the
>pitting. Nothing anywhere near the fried specimen you referenced
>earlier. I temporarily installed a new 1-3 switch today and ran the
>system for hour and noticed no heat increase on the fasteners. But I
>wouldn t expect that until many switch actuations and subsequent pitting
>of the contacts. I will put the Honeywell switch in when it arrives and
>keep an eye on it. If it shows any signs of impending failure I will
>research a Mil-Spec switch that might be a good replacement.
The Honeywell parts will be a cut-above the
Carling devices. I'm sure we're looking for
QA issues too. Loose rivets is one likely
root cause. The housings for these switches is
a molded and somewhat brittle plastic with
rather thin walls. The staking-height for
rivets that hold the contacts and terminals
together on the housing is an exceedingly close
tolerance process. A few thousandths too tight
and you crush the housing, too loose and you
loose gas-tightness in the joint and corrosion
gets you.
The failure I illustrated in the website
article seems to have initiated as a poor
fit of the radii of mating parts at the
teeter-totter pivot. Do you still have the
parts from your failed switch? I'd like to have
them even if you've already disassembled it.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 4
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| Subject: | Re: ELT Mounting Bracket |
It's likely the mounting angle has something to do with impact activation d
uring a crash, where most of the energy will be in the longitudinal directi
on, but some will be vertical.- In helicopters, this angle will be greate
r since they tend to impact at a steeper angle.
The g-switch is likely mounted axial with the box.- I presume the instruc
tions call for one end (the one opposite the 'bump') to be mounted forward.
- Is this the case?
-Cheers,
- Kyrilian
do not archive
--- On Sat, 9/6/08, Speedy11@aol.com <Speedy11@aol.com> wrote:
From: Speedy11@aol.com <Speedy11@aol.com>
Subject: AeroElectric-List: Re: ELT Mounting Bracket
Did you ask Ameri-King?
Stan
Do not archive
-
>Why
does the mount for the Ameri-King ELT have a "wedge" under the
>rearward end so that the radio is tilted 20 up in the
back?
Mount for a helo?
They're at an
angle...
-
Psssst...Have you heard the news? There's a new fashion blog, plus the late
st fall trends and hair styles at StyleList.com.
=0A=0A=0A
Message 5
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At 06:52 AM 9/6/2008 -0500, you wrote:
>Something like this?
>
>
><http://cgi.ebay.com/Tektronix-2230-100MHz-2ch-Digital-Storage-Oscilloscope_W0QQitemZ220277290907QQihZ012QQcategoryZ104247QQcmdZViewItemQQ_trksidZp1742.m153.l1262>http://cgi.ebay.com/Tektronix-2230-100MHz-2ch-Digital-Storage-Oscilloscope_W0QQitemZ220277290907QQihZ012QQcategoryZ104247QQcmdZViewItemQQ_trksidZp1742.m153.l1262
>
>
That could be a very useful tool and if you can get it cheap,
I would not discourage you from grabbing it. The 'scope
I mentioned, the TDS 2012 is my current favorite. You can
see it and its siblings at:
http://www2.tek.com/cmswpt/psdetails.lotr?ct=PS&ci=13295&cs=psu&lc=EN
It's a direct descendant of the TDS 210 that I purchased
6-7 years ago. These tools are noteworthy for their digital
storage of data for stable display on an LCD screen combined
with the ability to connect to outside clients. In the case
of the 210, it offered a printer interface that put screen
prints out to paper. This tool was used to produce hundreds
of measurement records for storage, documentation and
teaching. Many images from the 210 appear on aeroelectric.com
like . . .
http://www.aeroelectric.com/Pictures/Curves/99_Saturn_SL1.jpg
http://www.aeroelectric.com/Pictures/Curves/CH10V.jpg
I had a chance to sell the 210 to a client and purchase
a younger cousin, the 2012 about a year ago. This
one gives us a USB thumbdrive port instead of a printer
connection. When you hit the 'print' button, it delivers
a .jpg screen print and columnar ascii data files to
the thumbdrive. I've published some of this output data
on aeroelectric.com too . . .
http://www.aeroelectric.com/Pictures/Curves/S704-1_D-E_Transition_Diode_Suppression.jpg
you can put the .jpg into any handy image editor to
add leaders and text. I've not yet had occasion to
use the raw data files other than to 'play' with them
in Excel . . . but this is a very powerful upgrade to
our measurement capabilities. It also offers a USB
interface to a computer for automated measrument and
data recording.
Now, used 210s and 220s can be had off ebay for about
$500 ($1300 new). I've not seen the 2012s yet, it's
a bit early. There's a nice 1012 up now starting at
$400. See item 250290654969
Now, having offered suggestions for 'scopes particularly
useful to us in the OBAM aircraft venue, know that
ANY functioning 'scope of ANY capability at ANY price
is better than no 'scope at all! There are things to
be observed and measured for which there is no substitute
for "electronic eyes". The 'scope you cited would be
a very good buy as a single channel 'scope (90% of
my scope usage is in the single channel mode). If you
could get it for the starting bid, it would be an
excellent buy. Given that it's 'crippled' may well let
it sell for the starting bid price.
For the purposes of evaluating the energy consumption of
your strobe system, it's limited in that you would have
to photograph the screen, blow it up and do a manual
piecemeal integration by parts to deduce current
consumption. No great sin . . . this is how we used
to do it 30 years ago with ink pen traces on chart
recorders.
For folks interested in expanding their ability to "see"
those electrons, my best recommendation is the Textronix
2200 series devices like item 260281843724 on ebay. Any
of the 2200 60 Mhz or better is fine. Don't get too
wrapped around that higher-frequence-is-better-axle.
99% of everything we want to measure happens slower
than 60 million times per second!
These are modern solid state, still CRT display, light
and Textronix-quality. I've purchased perhaps a dozen
of these for folks over the years as "starter" scopes.
You want to get them cheap, under $200. 'Cause if it
craps, you'll want to put it back on ebay "as-is-for-parts"
and buy another one. The economics of having any 'scope
professionally repaired are not good unless you make
a living with these tools.
Avoid the 400 and 500 series 'scopes at any price.
They're excellent professional tools but complex
electronically (more likely to need repair) and
more difficult to learn to use. Also avoid rack-mounted
or plug-in modular scopes. These are mechanically
complex and more likely to suffer performance issues
that you'll not want to have fixed.
Now, with respect to the question before us, it
might be easier for me to go get some current traces
of a production airplane. I think I can get a current
probe or breakout harness into the power line of
the strobes on a Bonanza and get some really nice
data.
However, if you're personally interested in adding
that 'scope to your workbench, go for it. If you do
get it, we'll discuss ways you can go after the data
we're looking for.
Bob . . .
Message 6
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| Subject: | Re: ELT Mounting Bracket |
Yes - there is an arrow labeled "Forward" opposite the bump and it matches a similar
arrow on the radio that can only be installed one way. I will contact Ameri-King
next week to confirm but your analysis seems correct.
kyrilian_av(at)yahoo.com wrote:
> It's likely the mounting angle has something to do with impact activation during
a crash, where most of the energy will be in the longitudinal direction, but
some will be vertical. In helicopters, this angle will be greater since they
tend to impact at a steeper angle.
>
> The g-switch is likely mounted axial with the box. I presume the instructions
call for one end (the one opposite the 'bump') to be mounted forward. Is this
the case?
>
> Cheers,
> - Kyrilian
>
>
--------
RV-9A - Fuselage
Grumman AA1B-150 (RV-Trainer) Flying
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 2903#202903
Message 7
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Or currently $325. for the PDS5022. Mine seems to work fine off a little
12 volt cigarette lighter inverter.
http://saelig.com/
Ken
Message 8
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| Subject: | What am I doing wrong? |
I know, I know.
I get into these pickles and need a rescue - must be age.....
I want to replace a #4SWG welding cable with brass bar (copper not
available).
The diameter of #4 is (AE Connection, chap.8) 204 mils, or 0.204".
That, times
pi, should give the area. Divide the area by 1/8inch thick bar, gives 5127.1
mils, or
5 inches. I cannot for the life of me believe that a bar cross-section of 5
by 1/8 inches
Is equivalent (approximately) to this piece of #4 here in my hands.....
What am I doing wrong?
Ferg
$1/10 =10 cents; square both sides; $1/100 = 100 cents; 1 cent = $1.
Message 9
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| Subject: | Re: What am I doing wrong? |
Use pi x R^2
Sam Hoskins
On Sat, Sep 6, 2008 at 2:04 PM, Fergus Kyle <VE3LVO@rac.ca> wrote:
> I know, I know.
> I get into these pickles and need a rescue - must be age.....
> I want to replace a #4SWG welding cable with brass bar (copper not
> available).
> The diameter of #4 is (AE Connection, chap.8) 204 mils, or 0.204".
> That, times
> pi, should give the area. Divide the area by 1/8inch thick bar, gives
> 5127.1
> mils, or
> 5 inches. I cannot for the life of me believe that a bar cross-section of 5
> by 1/8 inches
> Is equivalent (approximately) to this piece of #4 here in my hands.....
> What am I doing wrong?
> Ferg
> $1/10 =10 cents; square both sides; $1/100 = 100 cents; 1 cent = $1.
>
>
Message 10
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| Subject: | Re: What am I doing wrong? |
If I recall, and without looking it up, I seem to recall that:
Area = pi x radius squared
Circumference = pi times diameter
Sam
On Sat, Sep 6, 2008 at 2:04 PM, Fergus Kyle <VE3LVO@rac.ca> wrote:
> I know, I know.
> I get into these pickles and need a rescue - must be age.....
> I want to replace a #4SWG welding cable with brass bar (copper not
> available).
> The diameter of #4 is (AE Connection, chap.8) 204 mils, or 0.204".
> That, times
> pi, should give the area. Divide the area by 1/8inch thick bar, gives
> 5127.1
> mils, or
> 5 inches. I cannot for the life of me believe that a bar cross-section of 5
> by 1/8 inches
> Is equivalent (approximately) to this piece of #4 here in my hands.....
> What am I doing wrong?
> Ferg
> $1/10 =10 cents; square both sides; $1/100 = 100 cents; 1 cent = $1.
>
>
Message 11
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| Subject: | Re: What am I doing wrong? |
At 12:04 9/6/2008, you wrote:
>I know, I know.
> I get into these pickles and need a rescue - must be age.....
> I want to replace a #4SWG welding cable with brass bar (copper not
>available).
> The diameter of #4 is (AE Connection, chap.8) 204 mils, or 0.204".
>That, times
>pi, should give the area.
Actially area is pi x radius squared. But why not just look up the
cross-sectional area?
Depending on stranding AWG-4 the wire table I have shows 41650 to
53314 CMA or 0.232 to 0.257 inch.
Using .257 that would give an area of .40369 sq. in.
>Divide the area by 1/8inch thick bar, gives 5127.1
>mils, or
>5 inches. I cannot for the life of me believe that a bar cross-section of 5
>by 1/8 inches
>Is equivalent (approximately) to this piece of #4 here in my hands.....
> What am I doing wrong?
If you call the area 0.4 and divide by .125 you get 3.2 inches.
Still wide...
>Ferg
>$1/10 =10 cents; square both sides; $1/100 = 100 cents; 1 cent = $1.
Message 12
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| Subject: | Re: What am I doing wrong? |
Oops, some edits got left out...
At 12:04 9/6/2008, you wrote:
>I know, I know.
> I get into these pickles and need a rescue - must be age.....
> I want to replace a #4SWG welding cable with brass bar (copper not
>available).
> The diameter of #4 is (AE Connection, chap.8) 204 mils, or
> 0.204" diameter.
>That, times
>pi, should give the area.
Pi x diameter is circumference.
Actially area is pi x radius squared. But why not just look up the
cross-sectional area?
Depending on stranding AWG-4 the wire table I have shows 41650 to
53314 CMA or 0.232 to 0.257 inch.
Using .257 that would give an area of .40369 sq. in.
>Divide the area by 1/8inch thick bar, gives 5127.1
>mils, or
>5 inches. I cannot for the life of me believe that a bar cross-section of 5
>by 1/8 inches
>Is equivalent (approximately) to this piece of #4 here in my hands.....
> What am I doing wrong?
If you call the area 0.4 and divide by .125 you get 3.2 inches wide.
Using .53 area you get 4.24 inches wide.
Still pretty wide...
>Ferg
>$1/10 =10 cents; square both sides; $1/100 = 100 cents; 1 cent = $1.
Message 13
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| Subject: | What am I doing wrong? |
No.
Circumference is pi*d
Area is pi*r(squared)
So. if d=0.204
Then r=0.102
And a=pi*0.102*0.102
a=3.14159*0.010404
a=0.03269 square inches
a/t=w
0.03269/0.125 = 0.2179 wide
Might as well say 1/8" x 1/4"
But you need enough to put a bolt thru.
Cut it 5/8" wide.
neal
_____________________________________________
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Fergus
Kyle
Sent: Saturday, September 06, 2008 2:05 PM
Subject: AeroElectric-List: What am I doing wrong?
I know, I know.
I get into these pickles and need a rescue - must be age...
I want to replace a #4SWG welding cable with brass bar (copper not
available).
The diameter of #4 is (AE Connection, chap.8) 204 mils, or 0.204".
That, times
pi, should give the area. Divide the area by 1/8inch thick bar, gives 5127.1
mils, or
5 inches. I cannot for the life of me believe that a bar cross-section of 5
by 1/8 inches
Is equivalent (approximately) to this piece of #4 here in my hands...
What am I doing wrong?
Ferg
$1/10 =10 cents; square both sides; $1/100 = 100 cents; 1 cent = $1.
Message 14
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| Subject: | Re: What am I doing wrong? |
Ferg,
Your math is wrong. Area of a circle is pi * r^2
Check this link for details:
http://en.wikipedia.org/wiki/American_wire_gauge
Mickey
Fergus Kyle wrote:
> I know, I know.
> I get into these pickles and need a rescue - must be age.....
> I want to replace a #4SWG welding cable with brass bar (copper not
> available).
> The diameter of #4 is (AE Connection, chap.8) 204 mils, or 0.204".
> That, times
> pi, should give the area. Divide the area by 1/8inch thick bar, gives 5127.1
> mils, or
> 5 inches. I cannot for the life of me believe that a bar cross-section of 5
> by 1/8 inches
> Is equivalent (approximately) to this piece of #4 here in my hands.....
> What am I doing wrong?
> Ferg
> $1/10 =10 cents; square both sides; $1/100 = 100 cents; 1 cent = $1.
>
>
>
--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
do not archive
Message 15
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| Subject: | Re: What am I doing wrong? |
Just a guess, but isn't the formula for area = pi x radius squared?
.204/2 = .102
.102 x .102 = .0104
.0104 x 3.1416 = .0327
.0327 / .125 = .261 or just over 1/4"
john
Fergus Kyle wrote:
> I know, I know.
> I get into these pickles and need a rescue - must be age.....
> I want to replace a #4SWG welding cable with brass bar (copper not
> available).
> The diameter of #4 is (AE Connection, chap.8) 204 mils, or 0.204".
> That, times
> pi, should give the area. Divide the area by 1/8inch thick bar, gives 5127.1
> mils, or
> 5 inches. I cannot for the life of me believe that a bar cross-section of 5
> by 1/8 inches
> Is equivalent (approximately) to this piece of #4 here in my hands.....
> What am I doing wrong?
> Ferg
> $1/10 =10 cents; square both sides; $1/100 = 100 cents; 1 cent = $1.
>
>
>
>
Message 16
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| Subject: | Re: What am I doing wrong? |
Formula is pi * r*r
3.141 * .102 * .102 = .032685
.032685/.125 = .2614
Thus width of bar required is +/- 1/4 inch.
I'm not an angineer but hope I'm right, good luck
Mike
----- Original Message -----
From: "Fergus Kyle" <VE3LVO@rac.ca>
Sent: Saturday, September 06, 2008 12:04 PM
Subject: AeroElectric-List: What am I doing wrong?
>I know, I know.
> I get into these pickles and need a rescue - must be age.....
> I want to replace a #4SWG welding cable with brass bar (copper not
> available).
> The diameter of #4 is (AE Connection, chap.8) 204 mils, or 0.204".
> That, times
> pi, should give the area. Divide the area by 1/8inch thick bar, gives
> 5127.1
> mils, or
> 5 inches. I cannot for the life of me believe that a bar cross-section of
> 5
> by 1/8 inches
> Is equivalent (approximately) to this piece of #4 here in my hands.....
> What am I doing wrong?
> Ferg
> $1/10 =10 cents; square both sides; $1/100 = 100 cents; 1 cent = $1.
>
>
>
Message 17
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At 01:07 PM 9/6/2008 -0400, you wrote:
>
>Or currently $325. for the PDS5022. Mine seems to work fine off a little
>12 volt cigarette lighter inverter.
>http://saelig.com/
>Ken
>
Yes, there ARE some attractive alternatives in Non-Tek
hardware. I bought a PDS5022 a couple of years ago and
my software guy has it. I don't know how much he uses
it. I've not taken the time to get familiar with it myself
but the short time that I played with it here in my
shop, it seemed quite capable for the investment.
There's another device from Saelig that's pretty interesting.
See:
http://www.saelig.com/miva/merchant.mvc?Screen=PROD&Product_Code=PS042&Category_Code
If I can ever get the fire-fights off my bench, I plan
to pick one of these up. I think it would be useful not
only as a low speed 'scope but the long term "chart recording"
looks attractive too.
Glad you mentioned the inverter thing. Yes, I velcroed
one of those little inverters to the top of a 17 a.h.
SVLA battery. When I was running the TDS 210 in the field,
my scope ran from the 115vac output and the Cannon bubble
jet printer ran directly from the 12v battery. Made for
a compact, self contained test tool. I used it a number
of times during my tenure at B/RAC/HB. The 'scope only needs
about 30 watts of snort as I recall. The itty-bitty inverter
works great.
Bob . . .
Message 18
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| Subject: | What did I do wrong? |
Well, of course - my memory of simple math let me down again!
Thanks to rjquillin and N8ZG, I have found that pi*D is the circumference.
On the other hand I got three different answers, since Circular Mils is a
square of D, the answers are a bit different.
In any event, what an advantage this net is!
Thanks again!
Ferg
Message 19
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| Subject: | What am I doing wrong? |
Not to be a pita, but brass has several times the resistance of copper,
depending on the alloy.
Van's Aircraft sells it (ES BUSS BAR-063X.5X12) which is just about what
you
need.
If you use brass, you'd need a lot wider or thicker strip (2 to 7 times
depending on alloy).
Vern Little
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Neal
George
Sent: September 6, 2008 12:43 PM
Subject: RE: AeroElectric-List: What am I doing wrong?
No.
Circumference is pi*d
Area is pi*r(squared)
So. if d=0.204
Then r=0.102
And a=pi*0.102*0.102
a=3.14159*0.010404
a=0.03269 square inches
a/t=w
0.03269/0.125 = 0.2179 wide
Might as well say 1/8" x 1/4"
But you need enough to put a bolt thru.
Cut it 5/8" wide.
neal
_____________________________________________
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Fergus
Kyle
Sent: Saturday, September 06, 2008 2:05 PM
Subject: AeroElectric-List: What am I doing wrong?
I know, I know.
I get into these pickles and need a rescue - must be age...
I want to replace a #4SWG welding cable with brass bar (copper
not
available).
The diameter of #4 is (AE Connection, chap.8) 204 mils, or
0.204".
That, times
pi, should give the area. Divide the area by 1/8inch thick bar, gives
5127.1
mils, or
5 inches. I cannot for the life of me believe that a bar cross-section
of 5
by 1/8 inches
Is equivalent (approximately) to this piece of #4 here in my hands...
What am I doing wrong?
Ferg
$1/10 =10 cents; square both sides; $1/100 = 100 cents; 1 cent =
$1.
Message 20
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| Subject: | Re: Switch problem |
Bob,
I'll have my shorted out switch in the mail on Monday.
Charlie Brame
RV-6A N11CB
San Antonio
---------------------------------------------------------------
Time: 04:34:28 AM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob@cox.net>
Subject: Re: AeroElectric-List: Switch problem
At 02:10 PM 9/4/2008 -0700, you wrote:
> Interestingly I have had almost the same problem. With a little
> over 200
> hours on the aircraft my Whelen strobe system stopped working. It
> did not
> open the 10A fuse, but when switched on the strobes would flash for
> about
> 10 seconds and then stop. I was thinking that it was a problem
> with the
> Whelen unit but it is in a very difficult place to get to in my RV8
> (under
> the floor) so I haven t yet gone to the effort to take up the floor to
> check it out. I looked at the fuse block and things looked good.
> Until I
> read this thread I didn t think about looking at the switch&..my
> mistake.
>
Not a mistake . . . just an unhappy discovery that
one ingredient in your system's recipe for success may
not be performing as-advertised.
> When I examined the switch today I discovered that the blue
> insulation
> on the Fast-On connectors had darkened considerably, indicating
> that they
> have been getting hot. They are still firmly attached to the wire
> but it
> appears there is an internal problem in the switch that is causing
> excessive heat.
>
A logical deduction.
> It is the B&C 1-3 switch referenced in this discussion. I have just
> ordered a few of the Honeywell switches from Digi-Key and will
> replace it
> with one of those.
>
I'd really like to put my hands on the overheated switch
for teardown, documentation and analysis.
> -------------snip---------------------------------------
Bob . . .
Message 21
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| Subject: | Ammeter reading oddly |
When I first start the engine, and then engage the alternator, the
Van's ammeter flips over to +20 for a few seconds.
Then it gradually descends to zero and settles a needle's width on
the -ve side of zero, where it sits for the duration.
If I turn the alternator off, the ammeter goes to -10 so I know it's
sensing something, but the slight -ve reading in flight bothers me.
Do you think it's just an adjustment issue on the gauge, or is
something else going on?
Thanks for ideas.
Neil
Message 22
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| Subject: | Re: Ammeter reading oddly |
At 05:49 PM 9/6/2008 -0400, you wrote:
>
>When I first start the engine, and then engage the alternator, the Van's
>ammeter flips over to +20 for a few seconds.
>Then it gradually descends to zero and settles a needle's width on the -ve
>side of zero, where it sits for the duration.
>If I turn the alternator off, the ammeter goes to -10 so I know it's
>sensing something, but the slight -ve reading in flight bothers me.
>
>Do you think it's just an adjustment issue on the gauge, or is something
>else going on?
Van's ammeter is an electronically signal conditioned instrument
with scale and offset adjustment pots inside. It sounds like
it's just out of calibration. This is ONE of the reasons
I don't recommend battery ammeters.
If you also have a voltmeter . . . THIS is the true guardian
of flight confidence. If the voltage is staying above
battery charge levels 13.8 minimum, 14.2 nominal, 14.6 maximum
then all is well in Electronville.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 23
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| Subject: | Re: What did I do wrong? |
At 13:14 9/6/2008, you wrote:
>Well, of course - my memory of simple math let me down again!
>Thanks to rjquillin and N8ZG, I have found that pi*D is the circumference.
>On the other hand I got three different answers, since Circular Mils is a
>square of D, the answers are a bit different.
> In any event, what an advantage this net is!
>Thanks again!
>Ferg
Mercy, the coffee and day finally kicked in...
No one ripped me earlier, despite my rightfully deserving it.
Besides being decimally challenged, and suffering fat fingers, I
forgot the CMA to in2 conversion of .7854 x 10e-6.
That .204 diameter listed is for solid wire, you don't have solid
wire and there is void area between the individual strands of the
cable, so to use that, solid, diameter would yield a result with some error.
You said #4 welding so it's likely not the 7x19/25 rope lay cable,
but either 259/27 or more likely 1666/36. The CMA of 1666/36 is
41650 from a stranded wire table. Cross sectional area in sq mils =
CMA x .7854; 41650 x .7854 = 32712 square mil or 0.032712 square
in. So .032712/.125 = 0.261696 width required to equal the same
conductor area.
Factoring in resistivity, from an old Chem-Physics handbook,
'properties of metals used as conductors' lists resistivity of
annealed copper as 1.72 and brass as 7. So brass has about 4.12
times more resistance. Take that .26 x 4.12 and you have a bit over
an inch; 1.07.
So, if I haven't again had a massive brain f**t, it would seem a bit
more than an inch width of your 1/8 inch brass would equal AWG-4
copper welding cable; at 20C.
I think I got it correct this time, but do check it out...
Ron Q.
Message 24
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| Subject: | Hangar Clean Out Day.... |
Hangar clean out day continues:
I've put the following items up for sale on eBay...
All these items are essentially new units (zero time). They were
purchased as I was building my plane and now I don't need.
The Stratus EA-81 and FWF Kit has no reserve - needless to say, I'll be
sleeping on the couch tonight!
Stratus EA-81 and Zenith 601 Firewall Forward Kit
http://tinyurl.com/6n9wxo
Apollo GX65 - Panel Mount Combo GPS/Comm unit
http://tinyurl.com/5u772b
Rocky Mountain's microMonitor (Engine + More Monitor)
http://tinyurl.com/5lg2ku
Dynon EFIS-D10 - Glass Cockput
http://tinyurl.com/5h9fvh
Don Honabach
Zodiac 601HDS
Tempe, AZ
DO NOT ARCHIVE
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