Today's Message Index:
----------------------
1. 01:50 AM - Cell phone microphone as compared to aviation microphone (Scott)
2. 02:16 AM - FW: Startup Checks (Andrew Butler)
3. 07:21 AM - Re: Z-19/RB Question (mikef)
4. 09:37 AM - Re: AT150 Interrogation Light (Fox5flyer)
5. 09:55 AM - Re: Cell phone microphone as compared to aviation microphone (Vernon Little)
6. 10:00 AM - Re: Re: AT150 Interrogation Light (Etienne Phillips)
7. 10:39 AM - Re: Re: AT150 Interrogation Light (Matt Prather)
8. 07:15 PM - Re: Headset components (Ernest Christley)
9. 10:18 PM - Re: Re: Z-19/RB Question (Ed Holyoke)
Message 1
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| Subject: | Cell phone microphone as compared to aviation microphone |
Does anybody have a reference on what a cell phone headset plug expects in
terms of impedance and/or excitation signal levels? And how this compares
to that produced by an aviation microphone?
I've wired a jack into my audio panel for plugging in my cell phone and it
"almost" works -- I can hear fine, but I have to yell in my aviation head
set's microphone to be heard at all by the recipient of my cell phone call
(and then only weakly).
Fine for checking voice mail before take off, but not so great for
requesting a clearance.
I suspect I need a preamp on the microphone line or perhaps an excitation
circuit to convert impedance to voltage but have been unsuccessful in
finding any data to help design the appropriate circuit.
Thanks!
Scott
Message 2
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| Subject: | FW: Startup Checks |
Darwin,
Here is a complete thread I had with Brad at E-Mag Ignitions earlier this
year on startup checks.
Cheers, Andrew.
------------------------------------------------------------------------
From: info@emagair.com [mailto:info@emagair.com]
Sent: 09 May 2008 16:57
Subject: RE: Startup Checks
Andrew: When an ignition is first powered up it has to wake up, load the
operating code, track engine position, determine when the next spark even
needs to happen, and finally trigger that spark event. If you power up
while the engine is running all this has to happen very quickly. Since P
models make their own power (as long as the engine is running), you
cannot shut down the processor. You can turn both the p-lead and the 12
supply OFF and it will still be "awake" doing its business as usual,
waiting to resume firing as soon as the p-lead is ungrounded. With E
models, however, you can power them OFF when running, and the ignition
(truly) will go dark - still no problem. Powering the E model OFF is
not the issue. It's when you 1) power an E model ON (while the engine is
running) and 2) with the p-lead ungrounded that you are asking it
to instantaneously wake up and start firing as described above. The
condition can be avoided (if encountered) by making sure the p-lead is
grounded (OFF) before powering (12 volt) ON an E model ignition while the
engine is running. Even so, if this happens, we aren't predicting
disaster. It will probably resume operation just fine, but there is no
reason to do it in the first place - that's all. I don't recall any
customers (yet) in Ireland - congratulations, you'll be number 1. Kindest
Regards,
Brad Dement
E-MAG Ignitions
2014 Greg Street Box 112
Azle, Texas 76020
(817) 444-5310
------------------------------------------------------------------------
From: Butler, Andrew [mailto:andrew.butler@nuigalway.ie]
Sent: Friday, May 09, 2008 10:29 AM
Subject: RE: Startup Checks
Thanks very much Brad, and you are welcome.
=B7 I am assuming that like a magneto, the plugs only spark when the unit
(connection 4) is NOT grounded.
=B7 What is the logic behind not switching off power to an E-MAG while the
engine is running? I am assuming that switching off power is okay, that
it is switching power back on while the engine is turning that is the
problem. What exactly is the event sequence associated with switching on
power while the engine is turning that is problematic?
=B7 Why is it problematic to turn power on while the P-MAG is
“live” i.e ungrounded?
I am not installing a rotary key switch, rather an individual power
switch for each ignition. It appears that I will need a two position
switch that allows me to control access to power and ground individually.
BTW, I think mine will be the first IE registered aircraft will dual
EMAGAIR ignitions. Do you know of any other customers in Ireland?
Cheers, Andrew.
RV71700
Galway, Ireland.
From: info@emagair.com [mailto:info@emagair.com]
Sent: 08 May 2008 17:07
Subject: RE: Startup Checks
Hi Andrew:
Thanks for considering us for your project.
The ignition check for E-MAG ignitions is very similar to that of
magnetos. You'll do your regular L/R (p-lead) check to make sure both
ignitions operate. The only difference is that for each P model ignition
you have installed (one or both) you'll add one additional sequence.
While switched to the individual P model(s), simply turn OFF the 12 volt
power that feeds that ignition for a few seconds to verify the engine
continues to run. If the engine runs, the internal alternator is
operating. If the engine quits, the alternator is not working. The
engine speed should be 1000 rpm or greater when you do this check.
There is no need to do this test with an E model as they don't have an
alternator. The L/R test is a p-lead (ON/OFF) test applicable to both E
and P models. The 12 power (ON/OFF) test is applicable to P models only,
and we discourage doing it with E models, so the FAQ you refer to is not
in conflict with the pre-flight ignition tests.
The Installation and Operating Guide also has some recommendations on
starting with our equipment - see Downloads page on our web site.
Don't hesitate to call or drop us a note if you have any other questions.
Kindest Regards,
Brad Dement
E-MAG Ignitions
2014 Greg Street Box 112
Azle, Texas 76020
(817) 444-5310
------------------------------------------------------------------------
From: Butler, Andrew [mailto:andrew.butler@nuigalway.ie]
Sent: Thursday, May 08, 2008 9:09 AM
Subject: Startup Checks
Hello,
I am awaiting delivery of an XP Superior IO 360. I had opted to replace
the mags with dual ignition from lightspeed. Then I was made aware that
Superior were about to start offering your product as an option also.
Given what I have learned, I am going to switch to dual P-Mags.
I need some advice on how to perform prefilght checks of each ignition.
Sure, switching off the power to both and see if the engine stops is
fine, but how do I determine whether each (or both) continue to fire when
power is disconnected?
Also, your FAQ says never switch on the E-Mag power with the engine
running. How does one then perform preflight checks on each ignition in
an E-Mag / P-Mag configuration?
Best regards, Andrew Butler.
RV71700.
Message 3
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| Subject: | Re: Z-19/RB Question |
Thanks Ed, That is a helpful confirmation of my understanding. I am building my
preflight/postflight checklists for this new z-19 system. I too don't want things
to go 'offline' if the alternator dies.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=195860#195860
Message 4
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| Subject: | Re: AT150 Interrogation Light |
Thanks for your reply, Bob. I appreciate all input. Well, I flew this morning
for about an hour and the first thing I checked was that my cell phone was turned
off. No change. At cruise the light was on steady. Next, I switched off
my left ignition which did two things. It stopped the noise in my headset and
the interrogation light on the transponder went out and started blinking normally!
I'm getting close. So, now I can tear into the wiring and see where
my left ignition wiring is in a common bundle with my headset receive and also
the transponder. What would you suggest here? Obviously I need to either separate
some wiring or do some shielding, but I'm not sure which way I should go.
If you were to home in on a specific wire, which would it be? My engine is
the NSI EA81 with stock Electromotive ignition modules. I personally don't
think anything is wrong with the ignitions. I believe I just have an ignition
wire somewhere causing interference. I'll dig my schematics out to see if I
can experience an epiphany.
Thanks again,
Deke
NE Michigan
nuckolls.bob(at)cox.net wrote:
> At 06:08 PM 7/30/2008 -0700, you wrote:
>
> >
> >
> > Thanks, Matt. You've given me several things to try. Yes, I do have a
> > new cell phone and the first thing I'll try is to turn it off and see what
> > happens. I also have dual electronic ignition and I'll do some
> > experimenting there too. One thing I've noticed is that one of the
> > ignitions has begun to make a noise in my headset. Basically I can hear
> > the trigger wheel going past the crank sensors, so I may have some wiring
> > that is leaking through to the headset wiring and possibly to the
> > transponder too. Something to look at. Other than that the ignitions
> > seem to be operating fine, as is the alternator, however I have no way of
> > turning it off. The transponder acts normally when the engine isn't
> > running. I my area its very rural with no interrogation pulses until I
> > get at least 2000agl, and even those are a long way off, so I'm not
> > getting bombarded with pulses.
> > However, I do have some things to try. Thanks.
> > Also, thanks to the others who offered help.
> >
> >
>
> Got in on this thread late but as others have noted,
> the transponder receiver is rather 'twitchy' with
> respect mistaking incoming noises as a bona fide
> "paint" from a ground based radar.
>
> A technician I used to work with had some rubber
> bands permanently installed over the hand grip
> on his line operated electric drill. I asked what
> they were for and he was happy to demonstrate. Use
> the rubber bands to hold the trigger made and then
> lay the drill on the floor right under the transponder
> antenna. From outside the cockpit you could see the
> reply light going nutso. He had one of those altitude
> and squawk code receiver/readouts that could then
> be used to see if the altimeter encoder was reading
> the same as the pitot-static test set altitude.
>
> The drill motor and the el-cheeso readout accessory
> took the place of some rather expensive test equipment
> for doing pitot static tests.
>
> Try pulling all the breakers/fuses except transponder.
> See if effects go away. Reinstall feeder protection
> one device at a time to see if you can identify the
> one that's upsetting the transponder. But all who
> have responded to this thread have identified possibilities
> for pesky little noises that might be causing the
> problem. It doesn't take much.
>
> Bob . . .
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=195880#195880
Message 5
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| Subject: | Cell phone microphone as compared to aviation microphone |
Hi Scott.
Try this:
MICIN---||-----o----/\/\/\/----X----/\/\/\----GND
0.1uF 100 Kohms 10 Kohm
Take the cellphone mic input from the "X"
This assumes that the MICIN signal from your headset is being biased by your
intercom. The capacitor is critical to remove DC from the signal which
would overload your cellphone mic input otherwise.
>From this, you'll see that the aircraft mic signal is being attenuated by
about 20 dB. This can be varied by adjusting the ratio of the two
resistors.
Good Luck
Vern Little
Vx Aviation
www.vx-aviation.com
Audio Mixer/Stereo Headphone Interface/Tone Annunciator/Annunciator Lamp
Controller and more.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Scott
Sent: July 31, 2008 1:40 AM
Subject: AeroElectric-List: Cell phone microphone as compared to aviation
microphone
Does anybody have a reference on what a cell phone headset plug expects in
terms of impedance and/or excitation signal levels? And how this compares
to that produced by an aviation microphone?
I've wired a jack into my audio panel for plugging in my cell phone and it
"almost" works -- I can hear fine, but I have to yell in my aviation head
set's microphone to be heard at all by the recipient of my cell phone call
(and then only weakly).
Fine for checking voice mail before take off, but not so great for
requesting a clearance.
I suspect I need a preamp on the microphone line or perhaps an excitation
circuit to convert impedance to voltage but have been unsuccessful in
finding any data to help design the appropriate circuit.
Thanks!
Scott
Message 6
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| Subject: | Re: AT150 Interrogation Light |
Could it be a spark-plug lead connected to the left ignition circuit that
has a problem with it's shielding?
Etienne
2008/7/31 Fox5flyer <fox5flyer@idealwifi.net>
> fox5flyer@idealwifi.net>
>
> Thanks for your reply, Bob. I appreciate all input. Well, I flew this
> morning for about an hour and the first thing I checked was that my cell
> phone was turned off. No change. At cruise the light was on steady. Next,
> I switched off my left ignition which did two things. It stopped the noise
> in my headset and the interrogation light on the transponder went out and
> started blinking normally! I'm getting close. So, now I can tear into the
> wiring and see where my left ignition wiring is in a common bundle with my
> headset receive and also the transponder. What would you suggest here?
> Obviously I need to either separate some wiring or do some shielding, but
> I'm not sure which way I should go. If you were to home in on a specific
> wire, which would it be? My engine is the NSI EA81 with stock Electromotive
> ignition modules. I personally don't think anything is wrong with the
> ignitions. I believe I just have an ignition wire somewhere causing
> interference. I'll dig my schematics out to see if I can experience an
> epiphany.
> Thanks again,
> Deke
> NE Michigan
>
>
Message 7
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| Subject: | Re: AT150 Interrogation Light |
Deke,
Sounds like you're making progress.. Does the engine have two plugs per
cylinder? If so, the problem could be as simple a faulty high tension
lead - or even a bad plug.
Along these lines, my guess would be that the source of noise is in the
high-energy portion of the system - as that seems most likely to radiate
offensive noise. That's why I'd guess the noise is from a high tension
lead.
If not dual plugs, does your system use a coil switcher? If so, maybe the
noise is in that portion of the circuit.
Good luck!
Matt-
> <fox5flyer@idealwifi.net>
>
> Thanks for your reply, Bob. I appreciate all input. Well, I flew this
> morning for about an hour and the first thing I checked was that my cell
> phone was turned off. No change. At cruise the light was on steady.
> Next, I switched off my left ignition which did two things. It stopped
> the noise in my headset and the interrogation light on the transponder
> went out and started blinking normally! I'm getting close. So, now I can
> tear into the wiring and see where my left ignition wiring is in a common
> bundle with my headset receive and also the transponder. What would you
> suggest here? Obviously I need to either separate some wiring or do some
> shielding, but I'm not sure which way I should go. If you were to home in
> on a specific wire, which would it be? My engine is the NSI EA81 with
> stock Electromotive ignition modules. I personally don't think anything
> is wrong with the ignitions. I believe I just have an ignition wire
> somewhere causing interference. I'll dig my s!
> chematics out to see if I can experience an epiphany.
> Thanks again,
> Deke
> NE Michigan
>
Message 8
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| Subject: | Re: Headset components |
Richard Girard wrote:
> I need to put a headset in my Shoei helmet that I use on my trike. I'm
> reluctant to take apart a $100 headset to get the mic and speakers if it's
> possible to do this with Rat Shack parts (or Digikey, Mouser, or.....).
> Anyone out there have any recommendations, part numbers or required specs?
>
> Thanks,
> Rick
>
>
Try Radio Shack part number 270-090.
I wired one directly to a microphone plug (ACS and Wicks have them for
about $5). I used a piece of piano wire to form a mic-boom, and used
some higher-end ($40) in-the-ear phones, that also plugged directly into
the intercom. It works great in our clubs C150, but is really noisy in
our Cherokees. My intercom is one of Jim Weir's 4-place kits. My
headset works great with it as long as it is the only one plugged in.
--
http://www.ronpaultimeline.com
Message 9
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| Subject: | Re: Z-19/RB Question |
Just one more thing, Mike. I periodically test the diode feeding the
E-Buss by turning on the master only or turning off the E-buss switch
first and making sure that the stuff on the E-buss is hot. I don't want
the alternate feed switch to be the single point of failure.
Pax,
Ed Holyoke
mikef wrote:
>
> Thanks Ed, That is a helpful confirmation of my understanding. I am building
my preflight/postflight checklists for this new z-19 system. I too don't want
things to go 'offline' if the alternator dies.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=195860#195860
>
>
>
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