Today's Message Index:
----------------------
1. 07:46 AM - Re: Re: Electronic Ignition spark advance signal boost (Robert L. Nuckolls, III)
2. 08:36 AM - Re: Electronic Ignition spark advance signal boost (Airdog77)
3. 08:54 AM - FMEA at ATL? (Andy Elliott)
4. 09:10 AM - Re: Electronic Ignition spark advance signal boost (Airdog77)
5. 09:38 AM - Re: Re: Electronic Ignition spark advance signal boost (Charlie England)
6. 10:05 AM - Re: Electronic Ignition spark advance signal boost (Airdog77)
7. 11:03 AM - Re: Electronic Ignition spark advance signal boost (Eric Page)
8. 11:22 AM - Re: Re: Electronic Ignition spark advance signal boost (C&K)
9. 12:18 PM - DIY captive stud terminal strips (Robert L. Nuckolls, III)
10. 02:15 PM - Re: DIY captive stud terminal strips (rayj)
11. 04:02 PM - Re: DIY captive stud terminal strips (user9253)
12. 04:24 PM - Re: Electronic Ignition spark advance signal boost CORRECTION (Robert L. Nuckolls, III)
13. 04:47 PM - Re: DIY captive stud terminal strips (Robert L. Nuckolls, III)
14. 08:11 PM - Re: Electronic Ignition spark advance signal boost (Airdog77)
Message 1
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Subject: | Re: Electronic Ignition spark advance signal |
boost
At 06:27 PM 12/17/2017, you wrote:
>
>Bob,
>
>Wow.... thanks! Really takes the guesswork out of configuring the
>amp for a gain of 10.
>
>I'm thinking it most likely doesn't matter, but just to be certain:
>the Electroair spark advance signal is only sent out over one wire,
>so I would not have any input from the Electroair unit to Pin 1 on
>the AD626. I assume this is ok for this configuration?
Hmmmmm . . . this offers potential for a different
kind of ground loop effect . . .
Any difference in voltage between 'ground' on the
ignition electronics and the EFIS electronics will
manifest as an offset in the system's calibration.
Just for grins, let's build this 'adapter'
with ground wires that go both directions . . .
just hook up the ignition system end and leave
the EFIS end open.
This configuration will offset the amplified
signal with a 1x influence . . . hooking
up only the EFIS end would put a 10x gain on the
displayed value. I'm thinking the first option
offers a high probability for satisfactory
performance.
Bob . . .
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Subject: | Re: Electronic Ignition spark advance signal boost |
Bob,
Sorry, but I'm having a hard time implementing this in my novice brain:
> just hook up the ignition system end
at Pin 8
> and leave the EFIS end open.
Is this the ground connection that crosses between to the 5V lead (pin 6) via
the 0.1 capacitor and the signal ground lead?
Any possible way you could diagram this out?
Thanks!
Wade
--------
Airdog
Wade Parton
Building Long-EZ N916WP
www.longezpush.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=476563#476563
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Looks like the infrastructure designers at KATL forgot about FMEA and the
concept of single-point failure avoidance. :( Guess they never had an
airplane with a dual magneto!
--------------------------
Andy Elliott, RV-8, N303RV
CL: 480-695-9568
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Subject: | Re: Electronic Ignition spark advance signal boost |
Ken, I would think these things (at least a version out there) would go down to
0.0 volts... Roger on using a higher resistor value.
Charlie, I think you're saying simply supply 12V power to the op amp (one rated
for 12V) at the V+ and V- pins? Spark advance input is obviously unchanged (at
+In). I guess the affect on the output being more linear is internal to the
op amp?
Regards,
Wade
--------
Airdog
Wade Parton
Building Long-EZ N916WP
www.longezpush.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=476566#476566
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Subject: | Re: Electronic Ignition spark advance signal boost |
On Mon, Dec 18, 2017 at 11:10 AM, Airdog77 <Airdog77@gmail.com> wrote:
>
> Ken, I would think these things (at least a version out there) would go
> down to 0.0 volts... Roger on using a higher resistor value.
>
> Charlie, I think you're saying simply supply 12V power to the op amp (one
> rated for 12V) at the V+ and V- pins? Spark advance input is obviously
> unchanged (at +In). I guess the affect on the output being more linear is
> internal to the op amp?
>
> Regards,
> Wade
>
> --------
> Airdog
> Wade Parton
> Building Long-EZ N916WP
> www.longezpush.com
>
> My comment was based on using one of the ancient op amp circuits, most of
> which get a bit nonlinear when output approaches the supply rail voltage.
> The much more modern instrumentation amp that Bob referenced doesn't seem
> to have that issue, making it simple to power it from the EFIS's 5V source.
On Bob's comment about ground references: I'm not up to speed on that
device, but I'd expect a differential amplifier to look at the voltage
difference between the two source voltages, and in this case, the <-> input
would be the ground reference at the device you're measuring. Since it's a
differential amplifier, I'd expect it to be immune to ground reference
issues, but hey; you don't know until you test.
If I were setting it up, I'd start by hooking the <+> input to the advance
output, the <-> input to the ground terminal *on the ignition module*. I'd
supply power from the EFIS & ground from the same spot the EFIS gets its
ground. I wasn't sure what Bob meant in his previous post, either, but he
may have been saying to supply ground from the ignition module; the same
point that supplies 'reference' to the <-> input. (By 'ground', I'm talking
about the power supply ground terminal; not the <-> input to the amp.)
Message 6
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Subject: | Re: Electronic Ignition spark advance signal boost |
Charlie,
Yes. Tracking. When I checked the Electroair manual, interestingly enough the
only ground available on that unit is the ignition module ground (vs the controller
unit).... since I was scrounging around to find a ground to use for -In
on the AD626 that Bob recommended.
Cheers,
Wade
--------
Airdog
Wade Parton
Building Long-EZ N916WP
www.longezpush.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=476571#476571
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Subject: | Re: Electronic Ignition spark advance signal boost |
Yes, I believe Bob meant to ground both signal and supply at the ignition module.
The op-amp won't know if there's a few mV ground potential difference on the
supply side; just the signal side. So, grounding the supply at the ignition
module instead of at the EIS won't affect operation, but it *will* give the
op-amp a good reference for the advance signal.
Wade, which model of the GRT EIS are you using? If it's the 4000, there appears
to be a "4.8V Exitation Output" on pin 25. The AD626 will draw a small fraction
of a milliamp, so it should be safe to use this pin to power the circuit.
Eric
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=476573#476573
Message 8
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Subject: | Re: Electronic Ignition spark advance signal boost |
Wade
As you surmise, there has to be two wires to to get the signal to your
amplifier and on to the EIS. So pin 1 of the amplifier in Bob's diagram
has to be grounded.
The complication is that you can ground that pin to numerous places in
the aircraft and each of those places will typically give a slightly
different reading when dealing with millivolt sensor signals. This may
or may not be significant in your application. Grounding pin 1 to the
ignition unit which is the source of your signal will likely be the best
choice and we recommend that you try that.
If that is difficult in your particular aircraft, or it proves
unsatisfactory, the next choice would probably be to try grounding pin 1
at the EIS ground. The issue with that is that any voltage difference
between the ground at the ignition unit and the ground at the EIS will
be amplified by a factor of 10 by the AD626. That may or may not be
significant depending on exactly what currents are flowing and what the
resistance is between the two different physical ground points. That
difference can change when you turn on or off various electrical
circuits in the aircraft which might introduce measurement errors. If
this makes sense to you, congratulations, you now understand the concept
of a ground loop and you can appreciate why bringing most of our
aircraft grounds to the common "forest of tabs" makes sense. Even
grounding both the EIS and the ignition unit at a forest of tabs might
not totally eliminate these ground errors though as there may well be
millivolt differences in the wire between the forest of tabs and the
ignition unit. All wires and connections have some resistance and any
current through a resistance results in some voltage drop however small.
We are trying to avoid adding such a voltage drop to your millivolt
sensor signal. So again running a ground wire from pin 1 of your
amplifier all the way to a connection at the ignition unit can make sense.
I am not familiar with your ignition but if your ignition coils are
grounded through a remote ignitor on the engine side of the firewall, it
is more likely that it will not matter where you ground the amplifier
pin. Coil grounds pulse several amps and you don't want that running
through the same wire as your sensor ground.
Ken
On 18/12/2017 12:36 PM, Charlie England wrote:
>
>
> On Mon, Dec 18, 2017 at 11:10 AM, Airdog77 <Airdog77@gmail.com
> <mailto:Airdog77@gmail.com>> wrote:
>
> <Airdog77@gmail.com <mailto:Airdog77@gmail.com>>
>
> Ken, I would think these things (at least a version out there)
> would go down to 0.0 volts... Roger on using a higher resistor value.
>
> Charlie, I think you're saying simply supply 12V power to the op
> amp (one rated for 12V) at the V+ and V- pins? Spark advance input
> is obviously unchanged (at +In). I guess the affect on the output
> being more linear is internal to the op amp?
>
> Regards,
> Wade
>
> --------
> Airdog
> Wade Parton
> Building Long-EZ N916WP
> www.longezpush.com <http://www.longezpush.com>
>
> My comment was based on using one of the ancient op amp circuits,
> most of which get a bit nonlinear when output approaches the
> supply rail voltage. The much more modern instrumentation amp that
> Bob referenced doesn't seem to have that issue, making it simple
> to power it from the EFIS's 5V source.
>
>
> On Bob's comment about ground references: I'm not up to speed on that
> device, but I'd expect a differential amplifier to look at the voltage
> difference between the two source voltages, and in this case, the <->
> input would be the ground reference at the device you're measuring.
> Since it's a differential amplifier, I'd expect it to be immune to
> ground reference issues, but hey; you don't know until you test.
>
> If I were setting it up, I'd start by hooking the <+> input to the
> advance output, the <-> input to the ground terminal *on the ignition
> module*. I'd supply power from the EFIS & ground from the same spot
> the EFIS gets its ground. I wasn't sure what Bob meant in his previous
> post, either, but he may have been saying to supply ground from the
> ignition module; the same point that supplies 'reference' to the <->
> input. (By 'ground', I'm talking about the power supply ground
> terminal; not the <-> input to the amp.)
>
>
Message 9
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Subject: | DIY captive stud terminal strips |
A short time ago we had some discussions that
included the mention of a technique for crafting
captive stud terminal strips.
Just ran across some pictures of an exemplar
technique . . .
https://goo.gl/cMQtA4
The base is crafted from some durable insulating
material. The article illustrated is built on a
piece of Delrin. Alternative materials include
6/6 nylon, phenolic, PVC and some thermoplastics.
Counter-sink the studs about 0.03 under-flush
and back-fill with epoxy . . . JB Weld is good.
Bob . . .
Message 10
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Subject: | Re: DIY captive stud terminal strips |
Many JB Weld products are steel reinforced.
Is it possible that the JB Weld used to secure the bolts might be
conduction path if the terminal strip is mounted on a conductive surface?
Raymond Julian
Kettle River, MN
The things we admire in men, kindness and generosity, openness, honesty,
understanding and feeling are the concomitants of failure in our system.
And those traits we detest, sharpness, greed, acquisitiveness, meanness,
egotism and self-interest are the traits of success. And while men
admire the quality of the first they love the produce of the second.
-John Steinbeck, novelist, Nobel laureate (1902-1968)
On 12/18/2017 02:18 PM, Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> A short time ago we had some discussions that
> included the mention of a technique for crafting
> captive stud terminal strips.
>
> Just ran across some pictures of an exemplar
> technique . . .
>
> https://goo.gl/cMQtA4
>
> The base is crafted from some durable insulating
> material. The article illustrated is built on a
> piece of Delrin. Alternative materials include
> 6/6 nylon, phenolic, PVC and some thermoplastics.
>
> Counter-sink the studs about 0.03 under-flush
> and back-fill with epoxy . . . JB Weld is good.
>
>
> Bob . . .
>
>
>
>
Message 11
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Subject: | Re: DIY captive stud terminal strips |
According to JB Weld website
https://www.jbweld.com/pages/faqs
Will J-B Weld conduct electricity?
No. J-B Weld is not considered to be a conductor. It is an insulator.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=476591#476591
Message 12
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Subject: | Re: Electronic Ignition spark advance signal boost |
CORRECTION
>
>The Electroair spark advance signal voltage output is from 0.00V to
>0.40V, and is scaled 0.01 volt per every degree of advance. So just
>to be clear:
>0.01V = 1 degree of advance
>0.10V = 10 degrees of advance
>0.28V = 28 degrees of advance
>
>What I would like to achieve is to amplify the spark advance signal
>voltage x 10 so that the GRT could see every 0.1V as 1 degree of
>spark advance, so again for clarity:
>0.1V = 1 degree of advance
>1.0V = 10 degrees of advance
>2.8V = 28 degrees of advance
There are hundreds of combinations of jelly-bean
parts that would suffice to your design goals.
My personal favorite of the moment is the Analog
Devices AD626 instrumentation grade amplifier.
It works well at 5.0 volt supply, has a huge
common mode input range, features factory trimmed
preset gains of 10 or 100. Has an output range
that easily brackets your requirement (0.03 to 4.7v).
The beauty of this critter is that no external
resistors or calibration adjustments are needed
to address your task.
https://goo.gl/Q3SYvj
They're a little pricey compared to some other
candidates
https://goo.gl/fxuF4Z
but I think the convenience of minimizing
external components combined with the simplicity
of calibration more than offsets the difference
in cost. I used this chip in dozens of data
acquisition tasks at Beech . . . it's still
a work-horse in my toolbox of get-er-done parts.
CORRECTION . . .
Must have suffered a transient short between the
headphones. Blew of the AD626 feature that makes
it 'magic'.
The inputs have a huge common mode signal rejection
range. This means that it amplifies only what is
impressed between pins 1 and 8 while ignoring
the difference in voltage between 1,8 and 2,3.
Hence, you tie pin 1 as close as practical to
ignition system ground, pin 8 to the advance
signal output. Amplifier ground pins 2,3 tie
to EFIS signal ground. This insures that the
output between 5/2,3 is 10x that between 8/1
irrespective of any difference in 'ground'
of the ignition system vs. the EFIS system.
Emacs!
Bob . . .
Message 13
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Subject: | Re: DIY captive stud terminal strips |
At 04:14 PM 12/18/2017, you wrote:
>
>Many JB Weld products are steel reinforced.
>
>Is it possible that the JB Weld used to secure the bolts might be
>conduction path if the terminal strip is mounted on a conductive surface?
>
>Raymond Julian
>Kettle River, MN
Not sure how much the epoxy's strength
can be attributed to particulate steel . . .
but the data sheet . . .
https://goo.gl/mHXUZX
suggests that any electrical contact between
such particles is nil to zero
volume resistivity of JB weld is 3.16 x 10^15
while that of copper is about 1.7 x 10^-8
if I recall correctly. This means that JB
Weld is pretty good electrical insulator!
Bob . . .
Message 14
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Subject: | Re: Electronic Ignition spark advance signal boost |
Hi Ken,
I talked with Electroair earlier today. They are taking a look at the AD6262 and
the best place to tie in the ground. It doesn't show up in the manual and
honestly I forgot about it, but on the experimental version there is a ground
wire coming off the Electroair controller unit. Their initial thought is that
would be the best place to tie in the A626 ground input.
I'll await Electoair's evaluation and press on from there.
Thanks a ton for all your advice.
Regards,
Wade
--------
Airdog
Wade Parton
Building Long-EZ N916WP
www.longezpush.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=476595#476595
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