homemade EFIS system and EMI

Thanks Dean, Elippse, Colin Lamb, Bob, AINut Don, Kayroc & Tim, I
really appreciate the advice.

Your comments rekindle my drive, I had hit a low point after designing
the data capture board, OS, circuits etc.. and then... being killed
with RF noise.

An odd, but beneficial I suppose, confluence of circumstances
involving a broken window pane and a mischievous dog and a storm lead
to water getting on the DC to DC power supply (11~14 DC - 12V, 5V,
3.3V +-) for the EPIA M motherboard. Not surprisingly it decided not
to continue functioning. I then pulled out a traditional power supply
to use, and.. amazingly 80% of the noise went away! I would hate to
curse but the blasted PW-60 #!@! (
http://store.ituner.com/ituner/pw60caatxpos.html ) power supply was the
primary culprit. It is a switching power supply with evidently little
RF and EMI protection. I am trying to find another DC-DC power supply
without these issues, they all appear to be switching power supplies, I
would rather deal with energy/heat loss than RF noise.

I don't want to go through the space and elaborate hastle of going from
the 11-14V bus to 120V AC to a bulky PC power supply (space is
critical) to 12,5,3.3V so I need to find a suitable non noisy power
supply and then deal with the issues you knowledgeable fellows
enumerated in the posts.

Thanks again to Dean, Elippse, Colin Lamb, Bob, AINut Don, Kayroc &
Tim.
Your comments rekindle my drive, I had hit a low point after designing
the data capture board, OS, circuits etc.. and then... being killed
with RF noise.

An odd, but beneficial I suppose, confluence of circucumstances
involving a broken window pane and a mischevious dog and a storm lead
to water getting on the DC to DC power supply (11~14 DC - 12V, 5V,
3.3V +-) for the EPIA M motherboard. Not surprisingly it decided not
to continue functioning. I then pulled out a traditional power supply
to use, and.. amazingly 90% of the noise went away! I would hate to
curse but the blasted PW-60 #!@! (
http://store.ituner.com/ituner/pw60caatxpos.html ) power supply was the
primary culprit. It is a switching power supply with evidently all
the wrong harmonics. I am trying to find another DC-DC power supply
without these issues, they all appear to be switching power supplies, I
would rather deal with energy/heat loss than RF noise.

I don't want to go through the space and elaborate hastle of going from
the 11-14V bus to 120V AC to a bulky PC power supply (space is
critical) to 12,5,3.3V so I need to find a suitable non noisy power
supply and then deal with the issues you knowledgable fellows
enumerated in the posts.

Thanks again to Dean, Elippse, Colin Lamb, Bob, AINut Don, Kayroc &
Tim.

You're welcome! Keep us informed, please, of your trials and successes.



jcpearce wrote:
Thanks Dean, Elippse, Colin Lamb, Bob, AINut Don, Kayroc & Tim, I
really appreciate the advice.

Your comments rekindle my drive, I had hit a low point after designing
the data capture board, OS, circuits etc.. and then... being killed
with RF noise.

An odd, but beneficial I suppose, confluence of circumstances
involving a broken window pane and a mischievous dog and a storm lead
to water getting on the DC to DC power supply (11~14 DC - 12V, 5V,
3.3V +-) for the EPIA M motherboard. Not surprisingly it decided not
to continue functioning. I then pulled out a traditional power supply
to use, and.. amazingly 80% of the noise went away! I would hate to
curse but the blasted PW-60 #!@! (
http://store.ituner.com/ituner/pw60caatxpos.html ) power supply was the
primary culprit. It is a switching power supply with evidently little
RF and EMI protection. I am trying to find another DC-DC power supply
without these issues, they all appear to be switching power supplies, I
would rather deal with energy/heat loss than RF noise.

I don't want to go through the space and elaborate hastle of going from
the 11-14V bus to 120V AC to a bulky PC power supply (space is
critical) to 12,5,3.3V so I need to find a suitable non noisy power
supply and then deal with the issues you knowledgeable fellows
enumerated in the posts.

Thanks again to Dean, Elippse, Colin Lamb, Bob, AINut Don, Kayroc &
Tim.
Your comments rekindle my drive, I had hit a low point after designing
the data capture board, OS, circuits etc.. and then... being killed
with RF noise.

An odd, but beneficial I suppose, confluence of circucumstances
involving a broken window pane and a mischevious dog and a storm lead
to water getting on the DC to DC power supply (11~14 DC - 12V, 5V,
3.3V +-) for the EPIA M motherboard. Not surprisingly it decided not
to continue functioning. I then pulled out a traditional power supply
to use, and.. amazingly 90% of the noise went away! I would hate to
curse but the blasted PW-60 #!@! (
http://store.ituner.com/ituner/pw60caatxpos.html ) power supply was the
primary culprit. It is a switching power supply with evidently all
the wrong harmonics. I am trying to find another DC-DC power supply
without these issues, they all appear to be switching power supplies, I
would rather deal with energy/heat loss than RF noise.

I don't want to go through the space and elaborate hastle of going from
the 11-14V bus to 120V AC to a bulky PC power supply (space is
critical) to 12,5,3.3V so I need to find a suitable non noisy power
supply and then deal with the issues you knowledgable fellows
enumerated in the posts.

Thanks again to Dean, Elippse, Colin Lamb, Bob, AINut Don, Kayroc &
Tim.

curse but the blasted PW-60 #!@! (
http://store.ituner.com/ituner/pw60caatxpos.html ) power supply was the
primary culprit. It is a switching power supply with evidently all
the wrong harmonics. I am trying to find another DC-DC power supply
without these issues, they all appear to be switching power supplies, I
would rather deal with energy/heat loss than RF noise.



The 110v power supplies used in desktop computers are also switching
supplies. So the problem is the cheapness of the 12v unit you selected.
I'd try another make unit and see if that works if not try putting the power
supply in its own shielded case and shielding and ferrite beading the
input/output leads from it.
Good luck and let us know what you workout!
John

"jcpearce" wrote in message
ups.com...
Thanks Dean, Elippse, Colin Lamb, Bob, AINut Don, Kayroc & Tim, I
really appreciate the advice.

Your comments rekindle my drive, I had hit a low point after designing
the data capture board, OS, circuits etc.. and then... being killed
with RF noise.

An odd, but beneficial I suppose, confluence of circumstances
involving a broken window pane and a mischievous dog and a storm lead
to water getting on the DC to DC power supply (11~14 DC - 12V, 5V,
3.3V +-) for the EPIA M motherboard. Not surprisingly it decided not
to continue functioning. I then pulled out a traditional power supply
to use, and.. amazingly 80% of the noise went away! I would hate to
curse but the blasted PW-60 #!@! (
http://store.ituner.com/ituner/pw60caatxpos.html ) power supply was the
primary culprit. It is a switching power supply with evidently little
RF and EMI protection. I am trying to find another DC-DC power supply
without these issues, they all appear to be switching power supplies, I
would rather deal with energy/heat loss than RF noise.

I don't want to go through the space and elaborate hastle of going from
the 11-14V bus to 120V AC to a bulky PC power supply (space is
critical) to 12,5,3.3V so I need to find a suitable non noisy power
supply and then deal with the issues you knowledgeable fellows
enumerated in the posts.

Thanks again to Dean, Elippse, Colin Lamb, Bob, AINut Don, Kayroc &
Tim.
Your comments rekindle my drive, I had hit a low point after designing
the data capture board, OS, circuits etc.. and then... being killed
with RF noise.

An odd, but beneficial I suppose, confluence of circucumstances
involving a broken window pane and a mischevious dog and a storm lead
to water getting on the DC to DC power supply (11~14 DC - 12V, 5V,
3.3V +-) for the EPIA M motherboard. Not surprisingly it decided not
to continue functioning. I then pulled out a traditional power supply
to use, and.. amazingly 90% of the noise went away! I would hate to
curse but the blasted PW-60 #!@! (
http://store.ituner.com/ituner/pw60caatxpos.html ) power supply was the
primary culprit. It is a switching power supply with evidently all
the wrong harmonics. I am trying to find another DC-DC power supply
without these issues, they all appear to be switching power supplies, I
would rather deal with energy/heat loss than RF noise.

I don't want to go through the space and elaborate hastle of going from
the 11-14V bus to 120V AC to a bulky PC power supply (space is
critical) to 12,5,3.3V so I need to find a suitable non noisy power
supply and then deal with the issues you knowledgable fellows
enumerated in the posts.

Thanks again to Dean, Elippse, Colin Lamb, Bob, AINut Don, Kayroc &
Tim.


Ahhh.... yes. I should have thought to mention the importance of a quiet
power supply. A PI filter between the supply and the PC is a good idea to
help ensure that switching noise from your supply doesn't get into your PC
board.

I'm used to designing my own power supplies for systems like this, so I
didn't stop to think that you might be using an off-the-shelf supply.

Dean

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

JC,

Having tackled this issue myself for other apps, I can point you to an
excellent resource, "The Art Of Electronics" by Horowitz & Hill. In
there, they outline some techniques witch you may consider paranoid, but
I have found to work. For instance, building an enclosure within an
enclosure. The outer enclosure is little more than a way to terminate
your outside wire connections (including power), allowing you to bring
them into a controlled environment where you can then apply such gross
tricks as caps & ferrite filters on your power lines and data lines
(don't forget fuses!). After you have performed whatever magic you can
on the in/outbound leads, you then bring the signal & power into the
inner enclosure.

Also remember that for homemade enclosures of bent & riveted aluminum,
small gaps where one flap is riveted to another can have gaps in then
which WILL leak RF. To fix this, your local electronics parts supplier
(or Digikey) will sell conductive tape. Welding also works. When
attaching the top of the enclosure, you could employ either one of those
fine mesh springy wire gaskets, or ... more tape.

Good luck,
Evan Carew

P.S.
IF you want me to forward some of the specific steps outlined in TAOE,
let me know.
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Thank you everyone for the input, now I am looking for some
prioritization. I received the new power supply from www.mini-box.com
and it is substantially better than the previous version
(http://www.mini-box.com/s.nl/sc.8/ca...it.A/id.356/.f ) however
I still get some noise in the radios. The new version is too big to
fit in the previous enclosure so it is sitting slightly apart from the
MB on its own.

I have started to jot down what the system wants to do, pictures and
status at
http://69.229.202.54:8080 Under the 'Image' folder one can see the
plane, the EPIA in the nose and the prototype ADC board.

So now I have a case that has to heavily part for the ATX power lines
to come into it & a non cased DC power supply. I have attached ferrite
beads to the power lines coming in/out with little improvement.

It takes time for many of the steps so I am looking for what you folks
think would be the 'biggest bang for the buck', or the right priority
to proceed with. (IE, build a brand new case for everything, build a
seperate case for the PSU, don't build a case right away but do X,Y,Z,
etc..)

Thanks once again for the brains helping noodle this over.

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

JC,

My comments/questions interspersed with your message:

jcpearce wrote:
Thank you everyone for the input, now I am looking for some
prioritization. I received the new power supply from www.mini-box.com
and it is substantially better than the previous version
(http://www.mini-box.com/s.nl/sc.8/ca...it.A/id.356/.f ) however
I still get some noise in the radios. The new version is too big to
fit in the previous enclosure so it is sitting slightly apart from the
MB on its own.

I have started to jot down what the system wants to do, pictures and
status at
http://69.229.202.54:8080 Under the 'Image' folder one can see the
plane, the EPIA in the nose and the prototype ADC board.

So now I have a case that has to heavily part for the ATX power lines
to come into it & a non cased DC power supply. I have attached ferrite
beads to the power lines coming in/out with little improvement.
Stupid question here JC, but it looks like you are using a PC style
switching power supply [high noise] to power your standard ATX style PC
board. Since most of the important voltages going into an ATX board are
either 5V or 12V, why aren't you simply using regulators off the plane's
battery to supply the power? It would seem to me to be both cheaper as
well as inherently less noisy (not to mention lighter). You wouldn't
even have to do any special parts sourcing on these regulators as they
are redily available at you local radio shack (karmic regulators anyone?).

For a break out of ATX voltages, see the following link:
http://www.7volts.com/atx2.jpg

It takes time for many of the steps so I am looking for what you folks
think would be the 'biggest bang for the buck', or the right priority
to proceed with. (IE, build a brand new case for everything, build a
seperate case for the PSU, don't build a case right away but do X,Y,Z,
etc..)

Thanks once again for the brains helping noodle this over.


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"jcpearce" wrote in message ups.com...
Thank you everyone for the input, now I am looking for some
prioritization. I received the new power supply from www.mini-box.com
and it is substantially better than the previous version
(http://www.mini-box.com/s.nl/sc.8/ca...it.A/id.356/.f ) however
I still get some noise in the radios. The new version is too big to
fit in the previous enclosure so it is sitting slightly apart from the
MB on its own.

I have started to jot down what the system wants to do, pictures and
status at
http://69.229.202.54:8080 Under the 'Image' folder one can see the
plane, the EPIA in the nose and the prototype ADC board.

So now I have a case that has to heavily part for the ATX power lines
to come into it & a non cased DC power supply. I have attached ferrite
beads to the power lines coming in/out with little improvement.

It takes time for many of the steps so I am looking for what you folks
think would be the 'biggest bang for the buck', or the right priority
to proceed with. (IE, build a brand new case for everything, build a
seperate case for the PSU, don't build a case right away but do X,Y,Z,
etc..)

Thanks once again for the brains helping noodle this over.


Check out this machine, only +5vdc required, linux capable...

http://www.diamondsystems.com/products/prometheus

I'm sure there are many more similar...