CCFL modification questions

[Rondor]

I'm trying to build a light box using a CCFL automotive light kit, originally
designed to be light rings for speaker enclosures (Roadmaster RNK100 round
"neon" - you know the type). From my research, I know these lamps use very high
(200V-600V DC) voltages, and that induction losses from the power supply to the
lamps, due to coiled or closely running wires, can lower the lamp's output, and
may damage the inverter. I have also read you are supposed to keep the power
leads to the lamps at a minimum, also to prevent reduced illumination. This
particular product uses extremely long power leads from the inverter to the
lamps (over 17' long!). The lamps don't really provide adequate illumination
for my intended application, and the extremely long power leads are also a major
problem.

My question is, can I safely shorten the leads from the inverter to the lamps
(say, to about 12")? Will this safely increase the illumination of the lamps to
their maximum, and not cause damage to the inverter? I am assuming so, since
this would decrease the voltage losses in the wiring, and allow the lamps to
recieve their full "requested" voltage. However, since this product was
designed with such long leads, could the inverter be designed to allow for the
line losses, i.e. it produces more voltage than required so as to mitigate those
losses? Could this cause damage to the lamps? Could they explode? I believe
they contain Mercury, so this is definately not something I would want to occur,
and is the reason for my reluctance in experimenting.

I know just enough about electronics design to make myself dangerous! Any
help will be MUCH appreciated. TIA

 

[Rondor]

As I've had no response to this post, would it be better posted elsewhere?

TIA

p.s. CCFL is Cold Cathode Fluorescent Lamp

In article <bs78rk01usn@drn.newsguy.com>, Rondor says...

I'm trying to build a light box using a CCFL automotive light kit, originally
designed to be light rings for speaker enclosures (Roadmaster RNK100 round
"neon" - you know the type). From my research, I know these lamps use very high
(200V-600V DC) voltages, and that induction losses from the power supply to the
lamps, due to coiled or closely running wires, can lower the lamp's output, and
may damage the inverter. I have also read you are supposed to keep the power
leads to the lamps at a minimum, also to prevent reduced illumination. This
particular product uses extremely long power leads from the inverter to the
lamps (over 17' long!). The lamps don't really provide adequate illumination
for my intended application, and the extremely long power leads are also a major
problem.

My question is, can I safely shorten the leads from the inverter to the lamps
(say, to about 12")? Will this safely increase the illumination of the lamps to
their maximum, and not cause damage to the inverter? I am assuming so, since
this would decrease the voltage losses in the wiring, and allow the lamps to
recieve their full "requested" voltage. However, since this product was
designed with such long leads, could the inverter be designed to allow for the
line losses, i.e. it produces more voltage than required so as to mitigate those
losses? Could this cause damage to the lamps? Could they explode? I believe
they contain Mercury, so this is definately not something I would want to occur,
and is the reason for my reluctance in experimenting.

I know just enough about electronics design to make myself dangerous! Any
help will be MUCH appreciated. TIA

 

[Richard Crowley]

Rondor wrote...

I'm trying to build a light box using a CCFL automotive
light kit, originally designed to be light rings for speaker
enclosures (Roadmaster RNK100 round "neon" - you know
the type). From my research, I know these lamps use very
high (200V-600V DC) voltages, and that induction losses
from the power supply to the lamps, due to coiled or closely
running wires,

Not clear how you could have "induction losses" from a DC
"signal". Do you have a refrence for this information, or are
you just guessing?

OTOH, how do you know it is DC? All mains-powered
fluorescent AND neon lamps run on AC that I have ever
seen. Even the DC-powered ones run on AC because they
use a transformer to boost the voltage.

can lower the lamp's output, and may damage the inverter.
I have also read you are supposed to keep the power leads
to the lamps at a minimum, also to prevent reduced
illumination.

Seems like general, common sense, advice.

This particular product uses extremely long power leads
from the inverter to the lamps (over 17' long!).

Likely because of the intended use (routing to speaker cabs).
And likely DESIGNED to run with such long leads.

The lamps don't really provide adequate illumination for my
intended application,

That may be a fundamental issue that cannot be addressed by
reducing the length of the wiring.

and the extremely long power leads are also a major problem.
My question is, can I safely shorten the leads from the inverter
to the lamps (say, to about 12")?

Can't see any electrical issue why you couldn't trim them to
whatever length is convienent.

Will this safely increase the illumination of the lamps to their
maximum,

I would be surprised if you saw ANY significant increase in
light output even by dramatically shortening the supply leads.

and not cause damage to the inverter?

What do the instructions say about trimming the length?
My gut feeling would be that the inverter is not in danger.

I am assuming so, since this would decrease the voltage
losses in the wiring, and allow the lamps to recieve their
full "requested" voltage.

The voltage losses are likely minimal and inconsequential.
Because the current is likely low (only a few milliamps).

However, since this product was designed with such long
leads, could the inverter be designed to allow for the line
losses, i.e. it produces more voltage than required so as to
mitigate those losses?

Seems unlikely to me.

Could this cause damage to the lamps? Could they explode?

I wouldn't worry about it if it were me. Of course, I would run
some worst-case tests and measurements before buttoning
everything up and forgetting about it.

I believe they contain Mercury,

Maybe, maybe not. Did you mean NEON or FLUORESCENT?
"Neon" (name used for other types of gas also) is where the
internal gas glows directly through a clear tube, while
fluorescent is where there is a white (or other color) phosphor
coating on the inside of the tube. I seem to recall that neon
(or other gas) tubes do NOT have mercury, while fluorescent
likely contain slight traces of mercury.

so this is definately not something I would want to occur,
and is the reason for my reluctance in experimenting.

If you are really that worried about "exploding" the lamps,
take adequate protection (run the tests with something to
protect you and your test setup from flying glass/chemicals.)

If it were me, I would wear safety goggles, but don't think
that any further protective gear is warranted.

 

[Rondor]

In article <vuk3ue8j182ef7@corp.supernews.com>, Richard Crowley says...

Rondor wrote...
I'm trying to build a light box using a CCFL automotive
light kit, originally designed to be light rings for speaker
enclosures (Roadmaster RNK100 round "neon" - you know
the type). From my research, I know these lamps use very
high (200V-600V DC) voltages, and that induction losses
from the power supply to the lamps, due to coiled or closely
running wires,

Not clear how you could have "induction losses" from a DC
"signal". Do you have a refrence for this information, or are
you just guessing?

Richard, I really appreciate you taking the time for a detailed reply to my
post. As I said below, I am a novice/hobbiest when it comes to this stuff. I
am currently living off a self designed off-grid solar system, and some of my
info comes from that experience. I've read that DC wiring can have large losses
if the conductors are run close together, but I may be incorrect by naming such
losses "induction". My understanding is that the magnetic fields created in the
conductors will create a resistance in the wire if the positive and negative
conductors are run adjacent to each other, with each conductor's field
negatively affecting the other. This is the loss to which I was trying to
refer.

OTOH, how do you know it is DC? All mains-powered
fluorescent AND neon lamps run on AC that I have ever
seen. Even the DC-powered ones run on AC because they
use a transformer to boost the voltage.

The power source for the controller/inveter is DC - from a lighter plug. The
instructions say the device can be powered with AC, but only after using a 12Vdc
converer (power brick). Also, due to the warning about running the light with
the wires bound together (see below), I assumed it is sending high voltage DC to
the lamps. I guess I should hook up my meter to determine if it's sending AC or
DC. My meter can read either up to 600v, so that should work. The controllers
for CCFls ARE called inverters, so it could very well be using AC.

can lower the lamp's output, and may damage the inverter.
I have also read you are supposed to keep the power leads
to the lamps at a minimum, also to prevent reduced
illumination.

Seems like general, common sense, advice.

This info came from a CCFL (Cold Cathode Fluorescent Lamp) manufacturer's design
info, which I believe these lamps are.

This particular product uses extremely long power leads
from the inverter to the lamps (over 17' long!).

Likely because of the intended use (routing to speaker cabs).
And likely DESIGNED to run with such long leads.

Exactally one of my questions, that maybe the controller was designed to work
with the long leads, and shortening them may cause damage.

The lamps don't really provide adequate illumination for my
intended application,

That may be a fundamental issue that cannot be addressed by
reducing the length of the wiring.

Agreed.

and the extremely long power leads are also a major problem.
My question is, can I safely shorten the leads from the inverter
to the lamps (say, to about 12")?

Can't see any electrical issue why you couldn't trim them to
whatever length is convienent.

OK. Good so far!

Will this safely increase the illumination of the lamps to their
maximum,

I would be surprised if you saw ANY significant increase in
light output even by dramatically shortening the supply leads.

Understood.

and not cause damage to the inverter?

What do the instructions say about trimming the length?
My gut feeling would be that the inverter is not in danger.

The instructions don't mention shortening the leads, but it does emphatically
warn against running them while bundled or tied together. From them: "Do not
gather the cables and bind together when the light is in use. Turning on the
light with the cables bound together will cause the controller unit to
malfunction." My understanding is that this would be because of the wiring
losses and resistances that I first spoke about above ("induction?").

I am assuming so, since this would decrease the voltage
losses in the wiring, and allow the lamps to recieve their
full "requested" voltage.

The voltage losses are likely minimal and inconsequential.
Because the current is likely low (only a few milliamps).

Again, I may be showing my ignorance, or lack of experience and training in
these matters. It may be the current losses, not the voltage, I should be
talking about.

However, since this product was designed with such long
leads, could the inverter be designed to allow for the line
losses, i.e. it produces more voltage than required so as to
mitigate those losses?

Seems unlikely to me.

Could this cause damage to the lamps? Could they explode?

I wouldn't worry about it if it were me. Of course, I would run
some worst-case tests and measurements before buttoning
everything up and forgetting about it.

Intelligent advice!

I believe they contain Mercury,

Maybe, maybe not. Did you mean NEON or FLUORESCENT?
"Neon" (name used for other types of gas also) is where the
internal gas glows directly through a clear tube, while
fluorescent is where there is a white (or other color) phosphor
coating on the inside of the tube. I seem to recall that neon
(or other gas) tubes do NOT have mercury, while fluorescent
likely contain slight traces of mercury.

The product is called "Neon" on the package, but I know true neon uses large,
noisy controllers, and these lamps do have a whiteish coating, and are incased
in clear lexan tubes. They look to me to be CCFLs, with the term "neon" used as
a marketing tool aimed at the ignorant masses.

so this is definately not something I would want to occur,
and is the reason for my reluctance in experimenting.

If you are really that worried about "exploding" the lamps,
take adequate protection (run the tests with something to
protect you and your test setup from flying glass/chemicals.)

If it were me, I would wear safety goggles, but don't think
that any further protective gear is warranted.

More intelligent advice! Believe me, due to past experiences, I have a great
respect for electricity, and the damage it can cause if treated incorrectly! I
just have absolutely no experience with these lamps, and there is little info
about them out there. Even though this product wasn't expensive, I would hate
to ruin it or any surrounding property due to my unknowledgable tinkering!
Mercury poisioning would also be a downer!

Again, many thanks for trying to help me in this matter. I appologize if my
ignorance has lead to any of this discourse being "stupidly obvious and
tedious".

Happy Holidays to you and yours!

 

[Richard Crowley]

"Rondor" wrote ...

Richard, I really appreciate you taking the time for a
detailed reply to my post. As I said below, I am a
novice/hobbiest when it comes to this stuff. I am
currently living off a self designed off-grid solar
system, and some of my info comes from that experience.
I've read that DC wiring can have large losses if the
conductors are run close together,

I'd like to see a reference for this. By itself, it doesn't make
any sense to me. Very large DC currents are commonly run
in conduits where the conductors are right next to each other.
Can't imagine any electrical/physical reason why there would
be "losses" from running DC through adjacent conductors.

but I may be incorrect by naming such losses "induction".

Inductance and capacitance have no effect on *steady-state*
(continuous) DC current. They are effectively AC phenomenon.
They may have brief (fractions of a second), transient effect
when turning on or off the DC current.

My understanding is that the magnetic fields created in the
conductors will create a resistance in the wire if the positive
and negative conductors are run adjacent to each other, with
each conductor's field negatively affecting the other. This is
the loss to which I was trying to refer.

No offense, but this sounds like 10% physics and 90% baloney.
Some of it makes sense if talking about AC (and only in very
non-conventional power circuits like high-frequency AC), but
it makes no sense at all when talking about DC. At least not
to me. Perhaps others reading this could shed different light?

OTOH, how do you know it is DC? All mains-powered
fluorescent AND neon lamps run on AC that I have ever
seen. Even the DC-powered ones run on AC because they
use a transformer to boost the voltage.

The power source for the controller/inveter is DC - from
a lighter plug. The instructions say the device can be powered
with AC, but only after using a 12Vdc converer (power brick).

I thought you were talking about the OUTPUT from the inverter
(the part with the over-long leads to the lamp.) That is what I
would strongly suspect is high-frequency AC.

Of course the INPUT is 12VDC as you already stated and I can't
think that the input wiring would be anything but completely
ordinary and straightforward.

Do you undestand how an inverter works?

Also, due to the warning about running the light with the wires
bound together (see below),

But if you are not "binding together" the wires, this seems
like a red herring.

I assumed it is sending high voltage DC to the lamps.

I don't see any way of coming to the conclusion that it is DC.
I would be very surprised if it were DC as there is no reason
to rectify it when the lamp doesn't care (or more likely even
runs better on AC)

I guess I should hook up my meter to determine if it's sending
AC or DC. My meter can read either up to 600v, so that
should work.

NO! NO! NO! D-A-N-G-E-R, WILL ROBINSON! (*)
I WOULD *NOT* CONDUCT THIS EXPERIMENT!!!!!
(* http://www.imdb.com/title/tt0058824/quotes )

It has a HIGH level of RISK (to both YOU and to your meter)
and it will prove nothing useful. If they are warning about
"binding together" the wires causing damage, then most
certainly connecting a meter carries a high risk. Unless you
have a specialty high-voltage probe (which I am assuming
you do NOT.)
http://www.fluke.com/images/80k15_02h_p.jpg

The controllers for CCFls ARE called inverters, so it
could very well be using AC.

I'd wager a nice dinner that they ouput high-frequency AC.

....

The instructions don't mention shortening the leads, but it
does emphatically warn against running them while bundled
or tied together. From them: "Do not gather the cables and
bind together when the light is in use. Turning on the light
with the cables bound together will cause the controller unit
to malfunction."

Since you appear to be planning on puting the inverter inside
the enclosure WITH the lamp(s), it would seem like you have
an even more ideal opportunity to route the cables as far apart
as physically possible, so I wouldn't worry about their "bound
together" warning.

My understanding is that this would be because of the wiring
losses and resistances that I first spoke about above
("induction?").

My best guess would be that the inverter is putting out high-
frequency AC, and the capacitance caused by "binding together"
the output wires would cause an extra load on the inverter output
(or even cause the marginal circuit design to change frequency
outside the design range.)

Again, I may be showing my ignorance, or lack of experience
and training in these matters. It may be the current losses, not
the voltage, I should be talking about.

The lamps likely run on high voltage (hundreds of volts), but
very low current. Power = current multiplied by voltage so
you can see that for equal power, the current goes down as
the voltage increases (and vice-versa).

There is always a trade-off between voltage and current, and
that is how the utility power grid works. They boost the voltage
very high (10s of thousands of volts) to travel long distances
over relatively small wires. Then they use transformers to
bring it down to 240/120V to send to individual houses.

I can't believe that it is the RESISTANCE of the wires that
would cause any reduction of light output from the lamps.
It seems more likely that it is capacitance from "binding
together" the wires that could likely cause problems at
high AC frequencies.

....

The product is called "Neon" on the package, but I know
true neon uses large, noisy controllers,

Not really. They use ordinary transformers that put out
high AC voltages. Some are quite small and completely
silent. Large neon signs use proportionally larger
transformers. They may be less careful about making
the transformers quiet because they know that they will
be many yards away from anybody to hear them.

and these lamps do have a whiteish coating,

In that case, they are certainly what I would call "fluorescent"
(or CCFL = Cold-Cathode Fluorescent)

and are incased in clear lexan tubes.

You didn't mention before that the lamps were enclosed in
plastic tubes. In this case, the risk from any possible explosion
is so low that I wouldn't give it a second thought.

Merry Christmas (*) and Happy New Year.
(* It is only the 2nd day of Christmas. Two turtle-doves, etc.)

 

[Rondor]

In article <vup6g6i1f17k8b@corp.supernews.com>, Richard Crowley says...

I've read that DC wiring can have large losses if the
conductors are run close together,

I'd like to see a reference for this. By itself, it doesn't make
any sense to me. Very large DC currents are commonly run
in conduits where the conductors are right next to each other.
Can't imagine any electrical/physical reason why there would
be "losses" from running DC through adjacent conductors.

Well, I've searched my bookmarks and saved pages, but can't find that reference.
Typical! I went back to the site that I thought the info came from, but
couldn't find it. (OT and BTW, since sites are constantly changing, I've started
to save pages of interest in .mht format so I will always have access to the
info) The article was quite technical, and even gave percentage losses occuring
from varying distances of the conductors to each other, saying that even 12"
apart, the effect was mesurable and significant.

Inductance and capacitance have no effect on *steady-state*
(continuous) DC current. They are effectively AC phenomenon.
They may have brief (fractions of a second), transient effect
when turning on or off the DC current.

The article was refering to the high current battery to inverter conductors.
Maybe because the current carried by these conductors does change, depending on
the load required by the inverter, is why the issue was discussed. No way to
know for sure, 'cause I can't find the blasted article!

My understanding is that the magnetic fields created in the
conductors will create a resistance in the wire if the positive
and negative conductors are run adjacent to each other, with
each conductor's field negatively affecting the other. This is
the loss to which I was trying to refer.

No offense, but this sounds like 10% physics and 90% baloney.
Some of it makes sense if talking about AC (and only in very
non-conventional power circuits like high-frequency AC), but
it makes no sense at all when talking about DC. At least not
to me. Perhaps others reading this could shed different light?

No offense taken at all. That's why I'm here asking these questions. If I have
inaccurate information flowing in my cranium, I want it OUT! In searching
for this article, I did come across some info about interference in DC wiring,
but they recommended twisting the power leads together the length of the run so
as to avoid this interference. Totally opposite from what I had thought was
correct!

I assumed it is sending high voltage DC to the lamps.

I don't see any way of coming to the conclusion that it is DC.
I would be very surprised if it were DC as there is no reason
to rectify it when the lamp doesn't care (or more likely even
runs better on AC)

This was based on my understanding at the time that dc conductors run together
caused losses or interference. Bad information leads to incorrect assumptions.

I guess I should hook up my meter to determine if it's sending
AC or DC. My meter can read either up to 600v, so that
should work.

NO! NO! NO! D-A-N-G-E-R, WILL ROBINSON! (*)
I WOULD *NOT* CONDUCT THIS EXPERIMENT!!!!!
(* http://www.imdb.com/title/tt0058824/quotes )

It has a HIGH level of RISK (to both YOU and to your meter)
and it will prove nothing useful. If they are warning about
"binding together" the wires causing damage, then most
certainly connecting a meter carries a high risk. Unless you
have a specialty high-voltage probe (which I am assuming
you do NOT.)
http://www.fluke.com/images/80k15_02h_p.jpg

My meter is an AC/DC clamp/probe meter rated up to 600v and 1000A (probes are
marked CATIII 600V). I know you can't use the clamp for voltage metering, but
you can tell if the current is AC or DC by the readout. (metering constant DC
current while on AC setting will cause a fluctuating or 0 readout) However,
since it's lowest measurement is 0.1A, and I am most probablly dealing with very
low current AC, and with that EXCELLENT warning from you, I will forgo any
metering!

You didn't mention before that the lamps were enclosed in
plastic tubes. In this case, the risk from any possible explosion
is so low that I wouldn't give it a second thought.

OK. Thanks for alleviating my experimentation fears. As I stated before, I've
seen firsthand the damage electricity can do, so I treat it with respect.
Again, many thanks for your taking the time to help me with this, Richard. You
have racked up many electric Karma points!

All the best to you and yours in the coming New Year!

 

[Richard Crowley]

"Rondor" wrote ...

My meter is an AC/DC clamp/probe meter rated up to
600v and 1000A (probes are marked CATIII 600V).
I know you can't use the clamp for voltage metering, but
you can tell if the current is AC or DC by the readout.
(metering constant DC current while on AC setting will
cause a fluctuating or 0 readout) However, since it's
lowest measurement is 0.1A, and I am most probablly
dealing with very low current AC, and with that
EXCELLENT warning from you, I will forgo any
metering!

Note that using any electrical/electronic equipment right
at the upper limit specification is not advisable. You
typically want at least a 100% safety factor, meaning
that I would use something rated to 600V only up to
300V. Note further that the output of those DC invertors
that run neon/fluorescent tubes may have higher-voltage
spikes even than the "nominal" RMS rating.

High-frequency AC is nasty stuff and quite a bit more
hazardous than line/mains voltage measurement. Even
after 40 years of experimenting with electronics, I
wouldn't even attempt to measure it even WITH my HV
probe unless there were a REALLY GOOD reason to
mess with it.

From what we percieve as your level of experience
with electronics, I would STRONGLY ADVISE you
to not mess with the HF AC except to route, connect,
and insulate it as recommended.