Today's Message Index:
----------------------
1. 04:04 AM - Re: Master contactor catch diode failure (Robert L. Nuckolls, III)
2. 04:05 AM - Re: Re: IVO Prop current limiter (Robert L. Nuckolls, III)
3. 04:39 AM - Re: Noisy radio system (user9253)
4. 04:59 AM - Re: IVO Prop current limiter (merlewagner2)
5. 07:21 AM - Re: Master contactor catch diode failure (William Hunter)
6. 12:40 PM - Re: Master contactor catch diode failure (Robert L. Nuckolls, III)
7. 12:47 PM - Re: Re: Master contactor catch diode failure (Robert L. Nuckolls, III)
8. 12:50 PM - Re: Master contactor catch diode failure (William Hunter)
9. 01:00 PM - Re: IVO Prop current limiter (kfav8r)
10. 01:11 PM - Re: Master contactor catch diode failure (Robert L. Nuckolls, III)
11. 01:24 PM - Re: Re: IVO Prop current limiter (Robert L. Nuckolls, III)
12. 01:49 PM - Re: Master contactor catch diode failure (William Hunter)
13. 02:56 PM - Re: Master contactor catch diode failure (Charlie England)
14. 05:33 PM - Re: Master contactor catch diode failure (user9253)
15. 06:33 PM - Re: Re: Master contactor catch diode failure (William Hunter)
16. 07:44 PM - Re: Re: Master contactor catch diode failure (don van santen)
Message 1
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| Subject: | Re: Master contactor catch diode failure |
At 02:52 PM 6/27/2017, you wrote:
>The most obvious answer is that the original diode was installed
>backwards. Maybe the supplied "packaged" assembly from Vans was
>incorrectly assembled under the heat shrink causing full battery
>voltage and hence current to forward bias the diode leading to its
>action as a fuse. The new assemblies shown in your photos leave no
>possible clue as to the direction the encapsulated diode is
>oriented. The external red band is fine and dandy, but if the diode
>under the shrink was accidentally reversed there is no way to know
>without "testing". I would suggest your "test" proved conclusively
>it was incorrect.
Agreed . . . with one other possibility . . .
I have encountered plastic diodes that
were incorrectly marked. Band on the
wrong end. It's rare but I think I've
seen it a couple of times. Further,
they were a one-of event, not a 'batch'
problem.
I'm not sure this is possible but it's
certainly low probability given modern
manufacturing and grading techniques
for diodes. But these days, there are
diodes and then there are DIODES. Without
knowing the critter's pedigree, we'll never
know.
In any case, replacing the diode is the
permanent fix.
Bob . . .
Message 2
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| Subject: | Re: IVO Prop current limiter |
At 01:37 PM 6/27/2017, you wrote:
>
>With Bob's prompting to move on to Plan B, I put together an
>Arduino-based IVOProp "controller."
>
>I bought an Arduino clone, a relay module, and a current sensing
>module, and wrote a program to monitor the prop current. When the
>current goes above 9 Amps for a sufficiently long time, the program
>opens the relay and shuts off the current. The red and green LEDS
>are triggered to indicate the current flowing and not flowing to the
>prop. The program leaves the relay open and the red LED on for a
>few seconds so the pilot gets the message that a limit was reached.
>
>I just ran the engine and put the prop through its paces, and the
>system seems to work well. There might be additional tweaking to
>the code needed, but I think it's pretty close to good.
GOOD for YOU!
>I'll be happy to share the code and links to the components if
>anyone is interested.
Yes, I'd be interested in seeing your work.
Bob . . .
Message 3
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| Subject: | Re: Noisy radio system |
Someone may correct me if wrong, but adding resistance to a circuit decreases the
current. Therefore adding resistance will decrease the load on magnetos.
An external antenna is a good idea. The ground plane does not necessarily have
to be sheet metal. A ground plane can be made using 6 or 8 radials of copper
tape or wire that are glued to the fabric.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=470545#470545
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| Subject: | Re: IVO Prop current limiter |
I would also like to take a look at your setup. I am planning on using an IVO mag
prop with in flight adj. Was hoping to do just what you have already done.
Way ahead of me!!!!
Merle
> I'll be happy to share the code and links to the components if anyone is interested.
hmmm, seems I screwed up the quoting somehow..
--------
KC1DNJ
General Radiotelephone
Commercial SEL
A&P
Building scale P51
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=470546#470546
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| Subject: | Re: Master contactor catch diode failure |
How does one (me) check a diode when it is installed on the contactor?
I assume that you want to have the master switch off and use DC resistance.
Does it matter what polarity to connect the leads?
Thanks,
Bill Hunter
At 02:52 PM 6/27/2017, you wrote:
The most obvious answer is that the original diode was installed backwards.
Maybe the supplied "packaged" assembly from Vans was incorrectly assembled
under the heat shrink causing full battery voltage and hence current to
forward bias the diode leading to its action as a fuse. The new assemblies
shown in your photos leave no possible clue as to the direction the
encapsulated diode is oriented. The external red band is fine and dandy,
but if the diode under the shrink was accidentally reversed there is no way
to know without "testing". I would suggest your "test" proved conclusively
it was incorrect.
Agreed . . . with one other possibility . . .
I have encountered plastic diodes that
were incorrectly marked. Band on the
wrong end. It's rare but I think I've
seen it a couple of times. Further,
they were a one-of event, not a 'batch'
problem.
I'm not sure this is possible but it's
certainly low probability given modern
manufacturing and grading techniques
for diodes. But these days, there are
diodes and then there are DIODES. Without
knowing the critter's pedigree, we'll never
know.
In any case, replacing the diode is the
permanent fix.
Bob . . .
Message 6
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| Subject: | Re: Master contactor catch diode failure |
At 09:20 AM 6/28/2017, you wrote:
>How does one (me) check a diode when it is installed on the contactor?
Just unhook one end (the small terminal) and use
your ohmmeter function to test continuity through
the diode. One configuration will show SOME value
of resistance, reversing the leads will show
infinite resistance.
>I assume that you want to have the master switch off and use DC
>resistance. Does it matter what polarity to connect the leads?
You test BOTH ways . . . looking for basically
NO conduction one way (off scale high resistance)
and some value of resistance the other way . . .
the exact value unimportant as it will vary
from one ohmmeter to another.
Bob . . .
Message 7
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| Subject: | Re: Master contactor catch diode failure |
At 04:16 PM 6/27/2017, you wrote:
>
>
>Bob McC wrote:
> > The most obvious answer is that the original diode was installed backwards.
>
>That was my initial thought too but the aircraft had 29 hours TTSN
>with that configuration.
>
>The RV-9A owner told me this incident happened on the first master
>switch actuation after battery replacement due to a totally
>discharged battery.
THIS IS NOT GOOD . . . If the diode WAS good
and fried after battery replacement, then the
battery was hooked up BACKWARDS . . . This
fries the catch diode and potentially, lots
of other stuff.
Years ago, I used to recommend adding a fuse
in series with the battery master contactor
wire that runs off to the master switch.
When paired with a catch diode on the contactor
the diode shorts out reversed voltage to the
contactor preventing closure while the fuse
blows preventing wire damage . . . and perhaps
damage to the diode as well.
But it sounds like this event went on long
enough to open the diode, close the contactor
and to put battery energy onto the ship's bus . . .
Bob . . .
Message 8
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| Subject: | Re: Master contactor catch diode failure |
Thanks,
Also, how warm do contactors get when they are energized?
I have two contactors mounted in a well underneath the backseat of my
airplane. This well is about three inches deep 20 inches wide and 12
inches long and it's completely sealed with no cooling air and since it is
constructed of foam core fiberglass It is Well insulated and therefore none
of the heat can get conducted out of the airplane.
I felt them and the contactors do get warm but the question is how warm can
they get and do they need any cooling air? Inflight only one contactor will
be energized however on the ground during maintenance I will have both
contactors energized.
THANKS AGAIN FOR YOUR HELP
Bill Hunter
On Jun 28, 2017 12:44 PM, "Robert L. Nuckolls, III" <
nuckolls.bob@aeroelectric.com> wrote:
> At 09:20 AM 6/28/2017, you wrote:
>
> How does one (me) check a diode when it is installed on the contactor?
>
>
> Just unhook one end (the small terminal) and use
> your ohmmeter function to test continuity through
> the diode. One configuration will show SOME value
> of resistance, reversing the leads will show
> infinite resistance.
>
>
> I assume that you want to have the master switch off and use DC
> resistance. Does it matter what polarity to connect the leads?
>
>
> You test BOTH ways . . . looking for basically
> NO conduction one way (off scale high resistance)
> and some value of resistance the other way . . .
> the exact value unimportant as it will vary
> from one ohmmeter to another.
>
> Bob . . .
>
Message 9
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| Subject: | Re: IVO Prop current limiter |
I'll get the info posted next week.
--------
Doug
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=470559#470559
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| Subject: | Re: Master contactor catch diode failure |
At 02:50 PM 6/28/2017, you wrote:
>Thanks,
>
>Also, how warm do contactors get when they are energized?
Too hot to touch but not hot enough to 'sizzle spit'
http://tinyurl.com/mpcgp3t
http://tinyurl.com/k6bwdqo
>I have two contactors mounted in a well
>underneath the backseat of my airplane.=C2 This
>well is about three inches deep 20 inches wide
>and 12 inches long and it's completely sealed
>with no cooling air and since it is constructed
>of foam core fiberglass It is Well insulated and
>therefore none of the heat can get conducted out of the airplane.
>
>I felt them and the contactors do get warm but
>the question is how warm can they get and do
>they need any cooling air? Inflight only one
>contactor will be energized however on the
>ground during maintenance I will have both contactors energized.
>
>THANKS AGAIN FOR YOUR HELP
Materials used in construction of these devices
is rated for operating at temperatures well in
excess of 100C . . . but of course, hotter than
you would want to touch.
Bob . . .
Message 11
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| Subject: | Re: IVO Prop current limiter |
At 03:00 PM 6/28/2017, you wrote:
>
>I'll get the info posted next week.
This might be another opportunity for an open source
project. Once you've finely tuned the code, we can
poke it into chips for mounting on a dedicated
ecb . . . have you considered solid-state
switching as opposed to relay?
Bob . . .
Message 12
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| Subject: | Re: Master contactor catch diode failure |
Thanks Bob!!!
The next time I have them humming for two hours at room temperature I will
lick them to see if spit sizzles.
Thanks again,
Bill Hunter
On Jun 28, 2017 1:15 PM, "Robert L. Nuckolls, III" <
nuckolls.bob@aeroelectric.com> wrote:
> At 02:50 PM 6/28/2017, you wrote:
>
> Thanks,
>
> Also, how warm do contactors get when they are energized?
>
>
> Too hot to touch but not hot enough to 'sizzle spit'
>
> http://tinyurl.com/mpcgp3t
>
> http://tinyurl.com/k6bwdqo
>
>
> I have two contactors mounted in a well underneath the backseat of my
> airplane.=C3=82 This well is about three inches deep 20 inches wide and
12
> inches long and it's completely sealed with no cooling air and since it i
s
> constructed of foam core fiberglass It is Well insulated and therefore no
ne
> of the heat can get conducted out of the airplane.
>
> I felt them and the contactors do get warm but the question is how warm
> can they get and do they need any cooling air? Inflight only one contacto
r
> will be energized however on the ground during maintenance I will have bo
th
> contactors energized.
>
> THANKS AGAIN FOR YOUR HELP
>
>
> Materials used in construction of these devices
> is rated for operating at temperatures well in
> excess of 100C . . . but of course, hotter than
> you would want to touch.
>
>
> Bob . . .
>
Message 13
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| Subject: | Re: Master contactor catch diode failure |
Do be aware that the temp it will get a *lot* hotter in your sealed up
insulated box than it will sitting on your kitchen counter. I wouldn't
do what you're talking about, because I wouldn't want to melt my
aircraft in that area. Component life might be a secondary issue, in
this case (pardon the pun).
On 6/28/2017 3:48 PM, William Hunter wrote:
>
> Thanks Bob!!!
>
> The next time I have them humming for two hours at room temperature I
> will lick them to see if spit sizzles.
>
> Thanks again,
>
> Bill Hunter
>
> On Jun 28, 2017 1:15 PM, "Robert L. Nuckolls, III"
> <nuckolls.bob@aeroelectric.com <mailto:nuckolls.bob@aeroelectric.com>>
> wrote:
>
> At 02:50 PM 6/28/2017, you wrote:
>
>> Thanks,
>>
>> Also, how warm do contactors get when they are energized?
>
> Too hot to touch but not hot enough to 'sizzle spit'
>
> http://tinyurl.com/mpcgp3t <http://tinyurl.com/mpcgp3t>
>
> http://tinyurl.com/k6bwdqo
>
>
> <http://tinyurl.com/k6bwdqo>
>> I have two contactors mounted in a well underneath the backseat
>> of my airplane. This well is about three inches deep 20 inches
>> wide and 12 inches long and it's completely sealed with no
>> cooling air and since it is constructed of foam core fiberglass
>> It is Well insulated and therefore none of the heat can get
>> conducted out of the airplane.
>>
>> I felt them and the contactors do get warm but the question is
>> how warm can they get and do they need any cooling air? Inflight
>> only one contactor will be energized however on the ground during
>> maintenance I will have both contactors energized.
>>
>> THANKS AGAIN FOR YOUR HELP
>
> Materials used in construction of these devices
> is rated for operating at temperatures well in
> excess of 100C . . . but of course, hotter than
> you would want to touch.
>
>
> Bob . . .
>
---
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Message 14
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| Subject: | Re: Master contactor catch diode failure |
I agree with Charlie. The heat given off by a fire (caused by hot contactors)
will be a whole lot hotter than the heat given off by contactors exposed to circulating
air. What is the purpose of an insulated box?
At what temperature will the diode start conducting in the reverse direction?
Nobody knows how hot it will get inside of the box because it depends on several
factors: size of box, how well it is sealed, insulating properties of the
box, ambient air temperature, wattage of the contactor, length of time contactor
is energized.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=470566#470566
Message 15
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| Subject: | Re: Master contactor catch diode failure |
I appreciate everyone's opinions and suggestions!!!
The airplane is a Velocity (pusher) so it is constructed of fiberglass foam
sandwich panels and I was trying to move as much of the heavy electrical
cables aft closer to the engine so I placed these components under the rear
bench seat. The rear seat "pedestal" (support structure) is a fiberglass
box integral with the fuselage also constructed with fiberglass foam
sandwich panels that equate to an "enclosed box".
I thought that this was an "elegant solution" to utilize this empty space
as an electrical equipment box however I didn't really think about the BTU
output of these contactors.
I guess I could cut some vent openings into the pedestal and that would
introduce some cabin ambient air into the box (four feet away from the
heater floor vents) however this would not be forced air ventilation but
still much better than an enclosed, sealed, and very insulated box.
Thanks,
Bill Hunter
On Jun 28, 2017 5:37 PM, "user9253" <fransew@gmail.com> wrote:
>
> I agree with Charlie. The heat given off by a fire (caused by hot
> contactors) will be a whole lot hotter than the heat given off by
> contactors exposed to circulating air. What is the purpose of an insulated
> box?
> At what temperature will the diode start conducting in the reverse
> direction? Nobody knows how hot it will get inside of the box because it
> depends on several factors: size of box, how well it is sealed, insulating
> properties of the box, ambient air temperature, wattage of the contactor,
> length of time contactor is energized.
>
> --------
> Joe Gores
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=470566#470566
>
>
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| Subject: | Re: Master contactor catch diode failure |
I would put the battery contactor as close to the battery as possible and
the starter contactor on thd engine side of the firewall. This is how the
RV 10 is done, battery in rear battery contactor inches away and starter
contactor on the front of the firewall. I realize that your are building a
pusher but this will work fine. This also keeps the heay generating
contactors out in the open and seperated from each other.
On Jun 28, 2017 18:37, "William Hunter" <billhuntersemail@gmail.com> wrote:
> I appreciate everyone's opinions and suggestions!!!
>
> The airplane is a Velocity (pusher) so it is constructed of fiberglass
> foam sandwich panels and I was trying to move as much of the heavy
> electrical cables aft closer to the engine so I placed these components
> under the rear bench seat. The rear seat "pedestal" (support structure) is
> a fiberglass box integral with the fuselage also constructed with
> fiberglass foam sandwich panels that equate to an "enclosed box".
>
> I thought that this was an "elegant solution" to utilize this empty space
> as an electrical equipment box however I didn't really think about the BTU
> output of these contactors.
>
> I guess I could cut some vent openings into the pedestal and that would
> introduce some cabin ambient air into the box (four feet away from the
> heater floor vents) however this would not be forced air ventilation but
> still much better than an enclosed, sealed, and very insulated box.
>
> Thanks,
>
> Bill Hunter
> On Jun 28, 2017 5:37 PM, "user9253" <fransew@gmail.com> wrote:
>
>>
>> I agree with Charlie. The heat given off by a fire (caused by hot
>> contactors) will be a whole lot hotter than the heat given off by
>> contactors exposed to circulating air. What is the purpose of an insulated
>> box?
>> At what temperature will the diode start conducting in the reverse
>> direction? Nobody knows how hot it will get inside of the box because it
>> depends on several factors: size of box, how well it is sealed, insulating
>> properties of the box, ambient air temperature, wattage of the contactor,
>> length of time contactor is energized.
>>
>> --------
>> Joe Gores
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=470566#470566
>>
>>
>>
>>
>>
>>
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