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Electronic signs
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clfe
electronics forum beginner


Joined: 20 Jun 2006
Posts: 7

PostPosted: Thu Jul 13, 2006 1:43 am    Post subject: Electronic signs Reply with quote

I am not familiar with electronic signs which have revolving messages -
other than seeing them. I'm asking for some tips. I have one or two - not
sure if only one is guilty or both are at the moment - but when both are
turned off, our problem ceases. They're causing interference to a 2 way
radio system. I"m planning on adding a filter of some sort - yet to be
determined. I have a few in mind to try - but til then, was looking for any
info on the type of sign and their operation.

Thanks
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Robert Baer
electronics forum Guru


Joined: 25 Mar 2005
Posts: 1159

PostPosted: Thu Jul 13, 2006 2:36 am    Post subject: Re: Electronic signs Reply with quote

clfe wrote:

Quote:
I am not familiar with electronic signs which have revolving messages -
other than seeing them. I'm asking for some tips. I have one or two - not
sure if only one is guilty or both are at the moment - but when both are
turned off, our problem ceases. They're causing interference to a 2 way
radio system. I"m planning on adding a filter of some sort - yet to be
determined. I have a few in mind to try - but til then, was looking for any
info on the type of sign and their operation.

Thanks


I presume these are modern neon signs.

If so, they use a solid-state inverter and theoretically are
regulated by the FCC.
You could try putting a shield around the inverter box, but you would
need to exercize great care and caution to keep the shield away from the
high voltage exit areas (where the neon tube goes inside the inverter
box), as there is tens of thousands of volts.
If you do not do it properly, at minimum permenant damage could occur
and those inverters run from $100 and up and *must* be EXACT replacements.
Alternately, use incandescent lights and there will be no RFI problems.
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clfe
electronics forum beginner


Joined: 20 Jun 2006
Posts: 7

PostPosted: Thu Jul 13, 2006 3:40 am    Post subject: Re: Electronic signs Reply with quote

"Robert Baer" <robertbaer@earthlink.net> wrote in message
news:Akitg.3858$vO.2030@newsread4.news.pas.earthlink.net...
Quote:
clfe wrote:

I am not familiar with electronic signs which have revolving messages -
other than seeing them. I'm asking for some tips. I have one or two - not
sure if only one is guilty or both are at the moment - but when both are
turned off, our problem ceases. They're causing interference to a 2 way
radio system. I"m planning on adding a filter of some sort - yet to be
determined. I have a few in mind to try - but til then, was looking for
any info on the type of sign and their operation.

Thanks
I presume these are modern neon signs.
If so, they use a solid-state inverter and theoretically are regulated
by the FCC.
You could try putting a shield around the inverter box, but you would
need to exercize great care and caution to keep the shield away from the
high voltage exit areas (where the neon tube goes inside the inverter
box), as there is tens of thousands of volts.
If you do not do it properly, at minimum permenant damage could occur
and those inverters run from $100 and up and *must* be EXACT replacements.
Alternately, use incandescent lights and there will be no RFI problems.


I'll have to check these out a bit more carefully. IF they're not going to
be able to be filtered without damaging the unit, then it may as well be
gotten rid of and be done with it. The "radio" system is more important than
the sign. I can tell you - the problem doesn't "seem" to be going through
the "electrical" system at the moment, as when the "antenna" was
disconnected - the problem stopped. The radio could be connected to a 12 VDC
battery for testing off the Main Line - but not so easily done. So, at least
for the moment, it seems to be emitting the signal via the air. This ought
to be interesting to check.

Thanks for the help!
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Robert Baer
electronics forum Guru


Joined: 25 Mar 2005
Posts: 1159

PostPosted: Fri Jul 14, 2006 7:29 am    Post subject: Re: Electronic signs Reply with quote

clfe wrote:
Quote:
"Robert Baer" <robertbaer@earthlink.net> wrote in message
news:Akitg.3858$vO.2030@newsread4.news.pas.earthlink.net...

clfe wrote:


I am not familiar with electronic signs which have revolving messages -
other than seeing them. I'm asking for some tips. I have one or two - not
sure if only one is guilty or both are at the moment - but when both are
turned off, our problem ceases. They're causing interference to a 2 way
radio system. I"m planning on adding a filter of some sort - yet to be
determined. I have a few in mind to try - but til then, was looking for
any info on the type of sign and their operation.

Thanks

I presume these are modern neon signs.
If so, they use a solid-state inverter and theoretically are regulated
by the FCC.
You could try putting a shield around the inverter box, but you would
need to exercize great care and caution to keep the shield away from the
high voltage exit areas (where the neon tube goes inside the inverter
box), as there is tens of thousands of volts.
If you do not do it properly, at minimum permenant damage could occur
and those inverters run from $100 and up and *must* be EXACT replacements.
Alternately, use incandescent lights and there will be no RFI problems.



I'll have to check these out a bit more carefully. IF they're not going to
be able to be filtered without damaging the unit, then it may as well be
gotten rid of and be done with it. The "radio" system is more important than
the sign. I can tell you - the problem doesn't "seem" to be going through
the "electrical" system at the moment, as when the "antenna" was
disconnected - the problem stopped. The radio could be connected to a 12 VDC
battery for testing off the Main Line - but not so easily done. So, at least
for the moment, it seems to be emitting the signal via the air. This ought
to be interesting to check.

Thanks for the help!



Maybe a safer way is to make a large metal (rectangular) box that
surrounds the whole sign, and use flat black painted wire mesh for the
side that one looks at / into.
That "wire mesh" should be no coarser than chicken wire; the size of
those holes determine the lowest frequency that can propagate thru and
get radiated.
The flat black paint helps greatly to disguize the mesh..
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clfe
electronics forum beginner


Joined: 20 Jun 2006
Posts: 7

PostPosted: Fri Jul 14, 2006 1:03 pm    Post subject: Re: Electronic signs Reply with quote

"Robert Baer" <robertbaer@earthlink.net> wrote in message
news:iJHtg.4364$vO.4135@newsread4.news.pas.earthlink.net...
Quote:
clfe wrote:
"Robert Baer" <robertbaer@earthlink.net> wrote in message
news:Akitg.3858$vO.2030@newsread4.news.pas.earthlink.net...

clfe wrote:


I am not familiar with electronic signs which have revolving messages -
other than seeing them. I'm asking for some tips. I have one or two -
not sure if only one is guilty or both are at the moment - but when both
are turned off, our problem ceases. They're causing interference to a 2
way radio system. I"m planning on adding a filter of some sort - yet to
be determined. I have a few in mind to try - but til then, was looking
for any info on the type of sign and their operation.

Thanks

I presume these are modern neon signs.
If so, they use a solid-state inverter and theoretically are regulated
by the FCC.
You could try putting a shield around the inverter box, but you would
need to exercize great care and caution to keep the shield away from the
high voltage exit areas (where the neon tube goes inside the inverter
box), as there is tens of thousands of volts.
If you do not do it properly, at minimum permenant damage could occur
and those inverters run from $100 and up and *must* be EXACT
replacements.
Alternately, use incandescent lights and there will be no RFI problems.



I'll have to check these out a bit more carefully. IF they're not going
to be able to be filtered without damaging the unit, then it may as well
be gotten rid of and be done with it. The "radio" system is more
important than the sign. I can tell you - the problem doesn't "seem" to
be going through the "electrical" system at the moment, as when the
"antenna" was disconnected - the problem stopped. The radio could be
connected to a 12 VDC battery for testing off the Main Line - but not so
easily done. So, at least for the moment, it seems to be emitting the
signal via the air. This ought to be interesting to check.

Thanks for the help!

Maybe a safer way is to make a large metal (rectangular) box that
surrounds the whole sign, and use flat black painted wire mesh for the
side that one looks at / into.
That "wire mesh" should be no coarser than chicken wire; the size of
those holes determine the lowest frequency that can propagate thru and get
radiated.
The flat black paint helps greatly to disguize the mesh..

Thanks very much - for the tips. I have spoken to one of the people in
charge and did some preliminary testing. While the system isn't totally
useless with the interfererence, it is a nuisance - so it has to be cleaned
up. But it does allow us time to check out any and all options. I hope to
meet with them again this weekend to see what our next step might be.

Thanks
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