Today's Message Index:
----------------------
1. 12:38 AM - Re: current limiting an alternator (Bob Verwey)
2. 04:51 AM - Re: Initial amp spike on PTT (Bill Bradburry)
3. 05:36 AM - Re: Digital multimeter recommendation (Eric M. Jones)
4. 08:13 AM - Re: Re: Digital multimeter recommendation (RGent1224@aol.com)
5. 09:25 AM - Re: Initial amp spike on PTT (Robert L. Nuckolls, III)
6. 10:03 AM - wire size (Scott Ahrens)
7. 10:13 AM - Re: Re: Digital multimeter recommendation (Henry Hallam)
8. 10:58 AM - Re: wire size (Robert L. Nuckolls, III)
9. 12:36 PM - Re: wire size (Scott Ahrens)
10. 03:54 PM - Re: Initial amp spike on PTT (Bill Bradburry)
11. 07:17 PM - Re: Re: wire size (Ed Holyoke)
12. 08:31 PM - Rejuvenating Ni-MH battery (Charles Brame)
13. 09:51 PM - Re: Re: Digital multimeter recommendation (Larry Winger)
Message 1
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| Subject: | Re: current limiting an alternator |
Bob, thanks for the insights; my concern was clearly born of ignorance. I
will implement the battery bus as suggested.
Best...
Bob Verwey
IO470 Bonanza A35 ZU-DLW
V6 Chevy Safari ZU-AJF
On 4 December 2012 19:55, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 10:35 AM 12/4/2012, you wrote:
> Hi Bob,
> As usual, you have put much more thought into your answer than I did into
> my question!
>
> My craft is powered by a Chevy V6 with a single aftermarket ignition coil,
> specifically designed for "high vibration environments". My endurance goals
> for alternator-out operations would be 30 minutes, as I will be strictly
> day VFR, and with a cruise speed of 100 knots I will have some options.
> Electrical loads are the usual ignition system, 2 comms, GPS, landing
> light, but really the very basics required. No fuel pump, high wing with
> carb. I had the H35 battery in mind, same as in the Bonanza.
>
> I am not considering an endurance bus. Okay. According to this posting
>
> http://tinyurl.com/cryc6w3
>
> The battery on an H35 is a 12 volt, rated at 29 a.h. for a one-hour rate.
> At 30 pounds this is not a wimpy device. On the certified airplane, it's
> paired with at least a 60A alternator. There might have been an larger
> alternator offered as an option.
> Many of our brothers are flying 17 a.h. batteries with alternators of 40
> amps or more.
> Can you articulate a foundation for your concerns? Even if you don't have
> an E-bus, consider a battery bus that supplies power for the ignition
> system. You should be able to fly this airplane with the battery master and
> alternator switches OFF.
>
> **
>
> **
> Bob . . .
>
> *
>
> *
>
>
Message 2
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| Subject: | Initial amp spike on PTT |
Short duration, but long enough to read it on the VOM. Maybe a second??
I have some trim indicators that are connected to this same ground (it is on
my stick) and they dim out when I hit the PTT. I am going to separate the
PTT from them today.
Bill B
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Wednesday, December 05, 2012 12:59 AM
Subject: Re: AeroElectric-List: Initial amp spike on PTT
<nuckolls.bob@aeroelectric.com>
At 10:43 PM 12/4/2012, you wrote:
><bbradburry@bellsouth.net>
>
>My hangar mate and I checked the current in the wire pulled to ground by
the
>PTT and found an initial spike of almost 2 amps. This seems excessive to
>me. After the initial spike it dropped down to a low number that I don't
>currently remember, but close to what I would think is acceptable in the
>millamp range.
What is the duration of the spike? The PTT
line coming out of the radio may have some
form of RFI ingress protection that includes
capacitance to ground. Any capacitor rapidly
discharged through the PTT circuit will produce
some large 'inrush' currents but they're typically
very short duration hence low energy.
Bob . . .
Message 3
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| Subject: | Re: Digital multimeter recommendation |
> Question I have a Fluke 8020 B multimeter and I think it needs to be calibrated.
The voltages appear to be off a bit. How much would it cost and anyplace where
it could be done. Thanks, Dick
Fluke 8020B....It a 30-year-old meter. See: http://www.radiomuseum.org/r/fluke_multimeter_8020b.html
And...I'm only guessing here...it sure doesn't owe you anything. Wrap it in plastic,
bless it, and bury it deep so some archaeologist in AD 5000 can find it.
Go to Ebay,, search "Fluke" and see what Santa Claus brings you. The 77 or 87 is
great.
You too Larry!
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=389880#389880
Message 4
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| Subject: | Re: Digital multimeter recommendation |
Thanks, Eric, But I used the "A" model when I worked on the Kodak Copiers.
Dang guess I'll have to get modern and give up my slide rule for a computer
Dick
In a message dated 12/5/2012 7:38:28 A.M. Central Standard Time,
emjones@charter.net writes:
--> AeroElectric-List message posted by: "Eric M. Jones"
<emjones@charter.net>
> Question I have a Fluke 8020 B multimeter and I think it needs to be
calibrated. The voltages appear to be off a bit. How much would it cost and
anyplace where it could be done. Thanks, Dick
Fluke 8020B....It a 30-year-old meter. See:
http://www.radiomuseum.org/r/fluke_multimeter_8020b.html
And...I'm only guessing here...it sure doesn't owe you anything. Wrap it
in plastic, bless it, and bury it deep so some archaeologist in AD 5000 can
find it.
Go to Ebay,, search "Fluke" and see what Santa Claus brings you. The 77 or
87 is great.
You too Larry!
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=389880#389880
Message 5
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| Subject: | Initial amp spike on PTT |
At 06:50 AM 12/5/2012, you wrote:
><bbradburry@bellsouth.net>
>
>Short duration, but long enough to read it on the VOM. Maybe a second??
Wow . . . I'm not sure we have enough data
to craft good hypothesis.
>I have some trim indicators that are connected to this same ground (it is on
>my stick) and they dim out when I hit the PTT. I am going to separate the
>PTT from them today.
Hmmmm . . . it would be interesting to
dig into this further. I cannot imagine
why the radio would impose such a stress
on the PTT line . . . take that back . . .
try this one for an "off the wall" notion.
If the PTT current presented by the radio
was limited to that which was necessary
(perhaps a few mA) then PTT switches and
relay contacts NOT characterized for very
low currents tend to gain contact resistance
due to corrosion. Switches designed to switch
significant loads (1A or more) tend to get
'cleaned' with the tiny arc that forms during
each opening of the contacts. A 'power' rated
switch can become flaky with age when loaded
at very low values.
Many upper-crust relays and switches come with
gold plated contacts. As long as the contacts
are never loaded beyond the "low level specs"
the layer of gold preserves contact integrity.
The same device can be used in 'power' control
but the arcing will burn the gold away and
the contact morphs into a 'power only' device.
Some years ago, my employer's receiving inspection
decided that it would be a good deal to 100%
test all incoming, crystal can relays at their
rated loads. Thousands of devices were put into
a fixture and 'tested' at 2A.
Problem is that many of these relays were destined
for jobs as managers of low level signals. The gold
plating was burned away during receiving inspection.
The crippled relays began to fail in large numbers
sometimes years after the airplane was delivered.
It's just possible that some thoughtful designer
at Garmin built a feature into the PTT line that
reduces the need for PTT switches with gold
contacts.
Any chance you could get a 'scope trace of this
current pulse?
Bob . . .
Message 6
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I am in the process of designing the electrical system for the my RV-7. I
know this will be a very basic question, but herding electrons is not one
of my strong suits. I am starting to run wires through the wing for all
the various electronics and I want to make sure I am reading the wire
size figure in Chapter 11 in AC 43-13. Just for my education lets use
Duckworth Landing Lights as example. I believe they recommend 16 AWG(for
55W lights) with a local / airframe ground. Wanting to understand how all
this stuff works I reference Figure 11-2 in AC 43-13.
First, I figure the AMPS drawn per light is 55 / 14 or 3.93; call it 4 AMPs
continuous. The wire run to the lights is estimated to be 18 feet. I am
including the length of the wing + a portion of the fuselage and an
estimate of the turns etc to reach the panel. Depending on how fine your
pencil is, the chart seems to indicate I could use AWG 18. If I want to
run the ground all the way back to the panel, then the length will be 36
feet. Then I need to use AWG 14 with the ensuing increase is weight. I
know the weight increase is minimal for one device. But landing lights,
nav lights, strobes, etc it all adds up.
Just in case someone wonders, my concern with local ground is the potential
of leakage into the avionics.
I am reading all this correctly. Thank you all for your kind advice.
Scott
Message 7
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| Subject: | Re: Digital multimeter recommendation |
If you want to do it yourself, here are some cal instructions:
http://electroniccalibrators.tpub.com/TB-9-6625-2266-35/TB-9-6625-2266-350003.htm
Henry
On Wed, Dec 5, 2012 at 8:11 AM, <RGent1224@aol.com> wrote:
> Thanks, Eric, But I used the "A" model when I worked on the Kodak Copiers.
> Dang guess I'll have to get modern and give up my slide rule for a computer
> Dick
>
> In a message dated 12/5/2012 7:38:28 A.M. Central Standard Time,
> emjones@charter.net writes:
>
> <emjones@charter.net>
>
>
>> Question I have a Fluke 8020 B multimeter and I think it needs to be
>> calibrated. The voltages appear to be off a bit. How much would it cost and
>> anyplace where it could be done. Thanks, Dick
>
>
> Fluke 8020B....It a 30-year-old meter. See:
> http://www.radiomuseum.org/r/fluke_multimeter_8020b.html
>
> And...I'm only guessing here...it sure doesn't owe you anything. Wrap it in
> plastic, bless it, and bury it deep so some archaeologist in AD 5000 can
> find it.
>
> Go to Ebay,, search "Fluke" and see what Santa Claus brings you. The 77 or
> 87 is great.
>
> You too Larry!
>
> --------
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge, MA 01550
> (508) 764-2072
> emjones(at)charter.net
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=389880#389880
>
>
Message 8
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>I know the weight increase is minimal for one device. But landing
>lights, nav lights, strobes, etc it all adds up.
>
>Just in case someone wonders, my concern with local ground is the
>potential of leakage into the avionics.
>
>I am reading all this correctly. Thank you all for your kind advice.
Have you read the chapters on wiring and
grounding in the AeroElectric Connection?
The rule of thumb for voltage drop limiting
is 5% of system voltage or 0.7 volts. A 4
amp load produces this size of drop with
a loop resistance of 175 milliohms. An 18'
run of wire would have to be run with
material having a resistance of about 175/18
or 10 milliohms per foot. 20AWG meets the requirement
for a single run of wire and local ground. This
exercise is described in a paper at:
http://tinyurl.com/ar6k3ed
Local grounds are fine as long as you perform
due diligence for eliminating airframe ground
loops in for potential victims by means of centralized
ground bussing as described in chapter on grounding
and figure Z15 in the wiring diagrams.
Bob . . .
Message 9
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The rule of thumb for voltage drop limiting
is 5% of system voltage or 0.7 volts. A 4
amp load produces this size of drop with
a loop resistance of 175 milliohms. An 18'
run of wire would have to be run with
material having a resistance of about 175/18
or 10 milliohms per foot. 20AWG meets the requirement
for a single run of wire and local ground. This
exercise is described in a paper at:
http://tinyurl.com/ar6k3ed
After reading (and re-reading) the link you sent I have calculated that
using an 18 AWG wire will meet the requirement. Using the constant of 700,
6.39 mOhm and 4 Amp draw I get a length of 27.39 feet. If I want to I can
step to a 16 AWG and the acceptable length is 43.64. All of this assuming
a local ground.
I will go back and re-read that chapter in your book. Thank you.
Scott
> I am in the process of designing the electrical system for the my RV-7. I
> know this will be a very basic question, but herding electrons is not one
> of my strong suits. I am starting to run wires through the wing for all
> the various electronics and I want to make sure I am reading the wire
> size figure in Chapter 11 in AC 43-13. Just for my education lets use
> Duckworth Landing Lights as example. I believe they recommend 16 AWG(for
> 55W lights) with a local / airframe ground. Wanting to understand how all
> this stuff works I reference Figure 11-2 in AC 43-13.
>
> First, I figure the AMPS drawn per light is 55 / 14 or 3.93; call it 4
> AMPs continuous. The wire run to the lights is estimated to be 18 feet. I
> am including the length of the wing + a portion of the fuselage and an
> estimate of the turns etc to reach the panel. Depending on how fine your
> pencil is, the chart seems to indicate I could use AWG 18. If I want to
> run the ground all the way back to the panel, then the length will be 36
> feet. Then I need to use AWG 14 with the ensuing increase is weight. I
> know the weight increase is minimal for one device. But landing lights,
> nav lights, strobes, etc it all adds up.
>
> Just in case someone wonders, my concern with local ground is the
> potential of leakage into the avionics.
>
> I am reading all this correctly. Thank you all for your kind advice.
>
> Scott
>
Message 10
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| Subject: | Initial amp spike on PTT |
Bob,
No I have no access to a scope.
As we were checking this problem with keying the mike out today, we found
that the RAC trim indicators were going to one end of the indicators and
dimming out when we keyed the mike. We have checked out the power and
ground wires for these indicators and they seem ok.
I called the Ray Allen Co about this and he suggests that I sounds like an
RF problem, but we fabricated a coax that ran from the radio to the antenna
by going completely outside the plane to insure that we were not getting RF
interference and it did not change the indicators performance.
I keep thinking that someone previously on the list had a problem with the
indicators a year or so ago and possibly found a fix???
B2
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Wednesday, December 05, 2012 12:25 PM
Subject: RE: AeroElectric-List: Initial amp spike on PTT
<nuckolls.bob@aeroelectric.com>
At 06:50 AM 12/5/2012, you wrote:
><bbradburry@bellsouth.net>
>
>Short duration, but long enough to read it on the VOM. Maybe a second??
Wow . . . I'm not sure we have enough data
to craft good hypothesis.
>I have some trim indicators that are connected to this same ground (it is
on
>my stick) and they dim out when I hit the PTT. I am going to separate the
>PTT from them today.
Hmmmm . . . it would be interesting to
dig into this further. I cannot imagine
why the radio would impose such a stress
on the PTT line . . . take that back . . .
try this one for an "off the wall" notion.
If the PTT current presented by the radio
was limited to that which was necessary
(perhaps a few mA) then PTT switches and
relay contacts NOT characterized for very
low currents tend to gain contact resistance
due to corrosion. Switches designed to switch
significant loads (1A or more) tend to get
'cleaned' with the tiny arc that forms during
each opening of the contacts. A 'power' rated
switch can become flaky with age when loaded
at very low values.
Many upper-crust relays and switches come with
gold plated contacts. As long as the contacts
are never loaded beyond the "low level specs"
the layer of gold preserves contact integrity.
The same device can be used in 'power' control
but the arcing will burn the gold away and
the contact morphs into a 'power only' device.
Some years ago, my employer's receiving inspection
decided that it would be a good deal to 100%
test all incoming, crystal can relays at their
rated loads. Thousands of devices were put into
a fixture and 'tested' at 2A.
Problem is that many of these relays were destined
for jobs as managers of low level signals. The gold
plating was burned away during receiving inspection.
The crippled relays began to fail in large numbers
sometimes years after the airplane was delivered.
It's just possible that some thoughtful designer
at Garmin built a feature into the PTT line that
reduces the need for PTT switches with gold
contacts.
Any chance you could get a 'scope trace of this
current pulse?
Bob . . .
Message 11
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Scott,
If you are going to do HID, 55w will be plenty enough. If you are going
to use halogen lights, plan for more than 55w. I had a pair of 75w for
years and when I went to 100w, I finally felt it was about bright
enough. I normally wig-wag them and everybody sees that coming. I turn
them both on steady for night landings. The weight difference for larger
gauge wire is negligible. Local ground will work fine.
Pax,
Ed Holyoke
On 12/5/2012 12:35 PM, Scott Ahrens wrote:
> The rule of thumb for voltage drop limiting
> is 5% of system voltage or 0.7 volts. A 4
> amp load produces this size of drop with
> a loop resistance of 175 milliohms. An 18'
> run of wire would have to be run with
> material having a resistance of about 175/18
> or 10 milliohms per foot. 20AWG meets the requirement
> for a single run of wire and local ground. This
> exercise is described in a paper at:
>
> http://tinyurl.com/ar6k3ed
> After reading (and re-reading) the link you sent I have calculated
> that using an 18 AWG wire will meet the requirement. Using the
> constant of 700, 6.39 mOhm and 4 Amp draw I get a length of 27.39
> feet. If I want to I can step to a 16 AWG and the acceptable length
> is 43.64. All of this assuming a local ground.
> I will go back and re-read that chapter in your book. Thank you.
> Scott
>
>
> I am in the process of designing the electrical system for the my
> RV-7. I know this will be a very basic question, but herding
> electrons is not one of my strong suits. I am starting to run
> wires through the wing for all the various electronics and I want
> to make sure I am reading the wire size figure in Chapter 11 in AC
> 43-13. Just for my education lets use Duckworth Landing Lights as
> example. I believe they recommend 16 AWG(for 55W lights) with a
> local / airframe ground. Wanting to understand how all this stuff
> works I reference Figure 11-2 in AC 43-13.
> First, I figure the AMPS drawn per light is 55 / 14 or 3.93; call
> it 4 AMPs continuous. The wire run to the lights is estimated to
> be 18 feet. I am including the length of the wing + a portion of
> the fuselage and an estimate of the turns etc to reach the panel.
> Depending on how fine your pencil is, the chart seems to indicate
> I could use AWG 18. If I want to run the ground all the way back
> to the panel, then the length will be 36 feet. Then I need to use
> AWG 14 with the ensuing increase is weight. I know the weight
> increase is minimal for one device. But landing lights, nav
> lights, strobes, etc it all adds up.
> Just in case someone wonders, my concern with local ground is the
> potential of leakage into the avionics.
> I am reading all this correctly. Thank you all for your kind advice.
> Scott
>
>
> *
>
>
> *
Message 12
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| Subject: | Rejuvenating Ni-MH battery |
Bob, et. al.,
I recall this was a thread awhile back, but I could not find my answer
in the archives.
Basically I have a 9.6v, 760mAh, Ni-MH battery pack (BP-200L) for an
ICOM handheld radio. The battery will no longer take a charge. Is
there any way to rejuvenate the battery? I emailed the question to the
ICOM Technical Service department, but they never bothered to respond.
One of the AeroElectric archive suggestions was to discharge a Ni-MH
battery with a dead short for 24 hours, then apply a 1 amp, 3v charge
for a few seconds, then recharge normally. However, I think this
recommendation must have been for a smaller battery, maybe a 1.5v
cell. Is there a recommended flash voltage and amperage to try and
rejuvenate my 9.6v battery?
Charlie Brame
RV-6A N11CB
San Antonio
Message 13
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| Subject: | Re: Digital multimeter recommendation |
Thanks, Eric. I'm about to pull the trigger on an 87 III series.
Larry
On Wed, Dec 5, 2012 at 5:36 AM, Eric M. Jones <emjones@charter.net> wrote:
> emjones@charter.net>
>
>
> > Question I have a Fluke 8020 B multimeter and I think it needs to be
> calibrated. The voltages appear to be off a bit. How much would it cost and
> anyplace where it could be done. Thanks, Dick
>
>
> Fluke 8020B....It a 30-year-old meter. See:
> http://www.radiomuseum.org/r/fluke_multimeter_8020b.html
>
> And...I'm only guessing here...it sure doesn't owe you anything. Wrap it
> in plastic, bless it, and bury it deep so some archaeologist in AD 5000 can
> find it.
>
> Go to Ebay,, search "Fluke" and see what Santa Claus brings you. The 77 or
> 87 is great.
>
> You too Larry!
>
> --------
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge, MA 01550
> (508) 764-2072
> emjones(at)charter.net
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=389880#389880
>
>
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