Today's Message Index:
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1. 10:06 AM - Re: Speaking of EMC filters (Robert L. Nuckolls, III)
2. 12:36 PM - Re: Speaking of EMC filters (Dave Saylor)
3. 01:00 PM - Re: Speaking of EMC filters (Robert L. Nuckolls, III)
4. 01:13 PM - Re: Speaking of EMC filters (Dave Saylor)
5. 03:24 PM - Re: autopilot servos (user9253)
Message 1
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Subject: | Re: Speaking of EMC filters |
At 09:34 PM 2/16/2012, you wrote:
<nuckolls.bob@aeroelectric.com>
I have received a couple of HID lamp kits for
evaluation with respect to EMC characteristics
in OBAM aircraft.
The first thing I did was order some HID conversions
for the high beams on my Sedona. Noises from these
lights are readily detectable while tuning around
on the AM radio.
The kit ballasts appear to have some sort of filter
in the harness between the ballast and lamp. However,
there is no such filter in the power input lead.
I've been side-tracked on a task for a customer but
I think I can get back on the bench next week. I'll
light one of these kits up on the bench and then
tune around with my DC-to-Light receiver. I can
get a rough idea of the fundamental excitation
frequency.
Saturday:
I did get a chance to fire up one of the HID
kits supplied for EMC evaluation.
On the bench, the light/ballast combination
produced very little noise in the killohertz
ranges (ADF, AM broadcast). Further, I could
not identify a fundamental frequency of
operation for the ballast in the short time
I was "searching". No doubt there is one
but it will take more diligence to identify.
What I did notice was that the system was a significant
BROADBAND noise source in the 100 MHz ranges.
This is not good. Broadband sources are generally
not electronic . . . they tend to be the result
of more chaotic behaviors like gazillions of
super-hot molecules crashing around in a
'glow tube'.
There is what appears to be an in-line filter
on the lead wires between ballast and lamp.
Given that it has to operate at voltage levels
in the thousands of volts, this is no trival
design job. Further, while one might THINK
that this filter is supplied to mitigate noise
from ballast electronics, it may well be that
its primary purpose is to reduce propagation
of noise from the lamp itself.
I've got to bug out for Wichita but I'll
be thinking about the next step for quantifying/
qualifying the problem.
Bob . . .
Message 2
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Subject: | Re: Speaking of EMC filters |
I have one of the lamps you're evaluating in each wing tip. One tip has an
Archer comm antenna (for comm 2) and one has an Archer nav antenna. I hear
a big FZZZZT from comm 2 every time the lamp flashes, or continuously if
it's on steady. It seems constant throughout the frequency range. The nav
flags if the signal isn't very strong. I haven't experimented with it
enough to say any more than if I turn off the HID, the signal comes in and
vice versa.
I sure appreciate your help, Bob. Can't wait to hear what you find.
Dave Saylor
AirCrafters
140 Aviation Way
Watsonville, CA 95076
831-722-9141 Shop
831-750-0284 Cell
On Sat, Feb 18, 2012 at 10:00 AM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> nuckolls.bob@aeroelectric.com**>
>
> At 09:34 PM 2/16/2012, you wrote:
> nuckolls.bob@aeroelectric.com**>
>
> I have received a couple of HID lamp kits for
> evaluation with respect to EMC characteristics
> in OBAM aircraft.
>
> The first thing I did was order some HID conversions
> for the high beams on my Sedona. Noises from these
> lights are readily detectable while tuning around
> on the AM radio.
>
> The kit ballasts appear to have some sort of filter
> in the harness between the ballast and lamp. However,
> there is no such filter in the power input lead.
> I've been side-tracked on a task for a customer but
> I think I can get back on the bench next week. I'll
> light one of these kits up on the bench and then
> tune around with my DC-to-Light receiver. I can
> get a rough idea of the fundamental excitation
> frequency.
>
> Saturday:
>
> I did get a chance to fire up one of the HID
> kits supplied for EMC evaluation.
>
> On the bench, the light/ballast combination
> produced very little noise in the killohertz
> ranges (ADF, AM broadcast). Further, I could
> not identify a fundamental frequency of
> operation for the ballast in the short time
> I was "searching". No doubt there is one
> but it will take more diligence to identify.
>
> What I did notice was that the system was a significant
> BROADBAND noise source in the 100 MHz ranges.
> This is not good. Broadband sources are generally
> not electronic . . . they tend to be the result
> of more chaotic behaviors like gazillions of
> super-hot molecules crashing around in a
> 'glow tube'.
>
> There is what appears to be an in-line filter
> on the lead wires between ballast and lamp.
> Given that it has to operate at voltage levels
> in the thousands of volts, this is no trival
> design job. Further, while one might THINK
> that this filter is supplied to mitigate noise
> from ballast electronics, it may well be that
> its primary purpose is to reduce propagation
> of noise from the lamp itself.
>
> I've got to bug out for Wichita but I'll
> be thinking about the next step for quantifying/
> qualifying the problem.
>
>
> Bob . . .
>
>
Message 3
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Subject: | Re: Speaking of EMC filters |
At 02:33 PM 2/18/2012, you wrote:
>I have one of the lamps you're evaluating in
>each wing tip. One tip has an Archer comm
>antenna (for comm 2) and one has an Archer nav
>antenna. I hear a big FZZZZT from comm 2 every
>time the lamp flashes, or continuously if it's
>on steady. It seems constant throughout the
>frequency range. The nav flags if the signal
>isn't very strong. I haven't experimented with
>it enough to say any more than if I turn off the
>HID, the signal comes in and vice versa.
>
>I sure appreciate your help, Bob. Can't wait to hear what you find.
Your findings are consistent with the theory
broad-band noise from the lamp's high energy
agitation of electrons on gas atoms.
Antenna proximity is going to be the elephant
in the room. I set my hand-held on one end of
a 7' bench from my signal generator which I
set up to produce an audible but noisy, modulated
signal. This would be roughly analogous to listening
to a weak station that is just above un-servicable.
I was carrying the HID around on a portable battery.
If I were 6' or more away from the hand held, I
could barely detect any influence of the HID
lamp on received signal.
From 3' away, the extra noise offered by the HID
lamp would have rendered the "remote station"
useless. Needless to say, an overwhelming
noise at those signal levels is not very
big. Indeed, probably insignificant to FM
radio reception in vehicles. I'll get some better
sense of the size of the problem when I get back
to M.L. on Monday.
In the mean time, can you hear the noise from a
hand held in the cockpit? Tune to open channel
and open the squelch. Turn the lamp on/off and
see if you can hear any change in the receiver's
normal background noise. Wearing headphones will
help.
Bob . . .
Message 4
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Subject: | Re: Speaking of EMC filters |
I'll check with a handheld on Monday.
--Dave Saylor
In the mean time, can you hear the noise from a
> hand held in the cockpit?
>
Message 5
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Subject: | Re: autopilot servos |
Here is a source of servos or linear actuators:
http://store.firgelli.com/
Here is an IC to control the speed of a motor or linear actuator:
http://www.mouser.com/Search/ProductDetail.aspx?qs=JaP0%252bruNJH%2F4ckdZw9AR1g%3D%3D
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=366552#366552
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