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EL Wire FAQ
What is this?
This is electroluminescent wire, basically, its a copper core wire,
with a phostphor material sputtered onto it, then 2 very fine small wires
like 26 gauge wrapped
around it, then ontop of that is a colors (sometimes - depends on the
color) plastic coating, then a normal plastic insulation on top of that.
When AC current at the
proper voltage, and frequency is applied to this wire, it glows very
beatifully.
What colors does it come in?
It comes in 9 different colors and costs 4 bucks a foot. You will need
a
circuit to drive it at 200VAC at 1200Hz. Sipex makes a nice SMT SOT-8
chip that takes only a couple of external components, all surface mount.
It runs off a single 1.5V battery. Its kind of tricky to terminate,
I
used heatshrink tubing that had an internal glue layer to make a
water-proof seal. I'll probably put the entire driver circuit in the
heatshrink and only leave the battery leads exposed on my next try.
Technical stuff - Do you know
how to work with it?
Lets talk about it PRIOR to spending a fortune on this stuff..
So far as I know it's pretty simple stuff. The intensity of the
light
generated is actually a response to the frequency of the AC current
you
run through it as opposed to voltage. You can simply put a standard
household outlet on one end and plug it in to the wall (or an inverter
for that matter).
It burns out. At 60hz (household) it'll lose 1/2 it's luminosity
in
about 7 years of continuous use. At higher frequencies, this
is much
faster. At 2000hz it's still in the range of hundreds of hours
and
the
stuff is quite bright.
I think it never actually burns out but it does burn down.
Also, LiveWire makes battery-powered inverters to power this stuff that
they sell for $15 or so. The current draw is miniscule.
I think it's
something like 1 amp/800 feet or on that order. Very low draw.
A few notes:
The intensity is based on voltage and the color is based on frequency.
I've used their inverters, and they work with 9V, 12V and 18V
battery
sources. The last time I checked, they had 4 different inverters.
They
were low power/low frequency, low power high frequency, high power
low
frequency, high power high frequency. The low power inverters
are used
for strands up to 15' and the high power ones can be used up to 50'.
We
always pushed those limits and was able to run a 200' strand with a
12VDC to 110VAC RV inverter. The base phosphor glows with a blue/aqua
and the other colors are derived by colored coatings. The colors
I
thought were best were the blue/aqua and the violet. I didn't
like the
orange/gold very much, it seemed somewhat off colored. Be careful,
If
left in the sun, the colored coatings will bleach out with time.
One
very nice thing about this EL wire is it's lack of latency. When
the
electricity is off, it does not continue to glow. The inverters
that
are sold by LiveWire have an interesting wave pattern that causes the
EL
wire to produce a strobe effect. When you swing the wire you
can see
the distinct pulses. This worked against Greg when he put the
wire on
the spokes of his bike and tried to synchronize them with the speed
of
the wheels, but can be put to use with other applications.
I just wanted to reiterate a couple of technical points to make sure
I'm
clear:
- The fibre's brightness is a function of the voltage applied.
- The colour (to a degree) varies with the frequency, and changing
the
frequency can yield some interesting effects.
Someone also mentioned that they sell 4 different types of inverters
- I
was curious if there were inverters wherein the frequency could either
be manually (or ideally, programmatically) altered. I'm a programmer,
but don't have much electrical experience, but I'd love to have a system
where I could have the frequency altered based on a program, or some
other external signal. Any ideas?
.... No such inverters that I'm aware of, but it should be pretty
straightforward to build one. If you want something highly portable,
it'll
take a dedicated-hardware design.
If it's for a base camp, though - the easy
way would be to use a
programmable frequency generator to drive an inverter. Some frequency
generators have e.g. serial ports. You could also use the
programmable
squarewave generator that's built into all PCs - the speaker driver.
It's
clocked at 1.193182 MHz. You write a value to the divisor register
and it
produces a square wave by dividing the clock by the divisor.
This lets you
produce a frequency from 1.193182 MHz down to 18.2 Hz, which I suspect
encompasses the entire useful range :)
If the lowest frequency of use is 50Hz or
so, you could probably get away
with modifying a generic 60Hz 12VDC->120VAC inverter: replace its clock
circuitry with a feed from your programmable frequency generator.
Then put a
step-up transformer on the output to bring the 120VAC up to whatever
you want.
Below 50Hz, the cores of the inverter transformer and step-up transformer
are
liable to saturate.
A couple application notes.
I just dug out my data sheets from a while back.
The efficiency of the wire peaks at 100VAC but is still acceptable as
low
as 60VAC and starts tapering off above 120VAC.
Power consumption is higher at higher frequencies. It seems to
average
200mw/meter.
Brightness at 100VAC is nearly 3 times greater at 1000hz compared to
200hz.
Current consumption is averaging around .002 Amps per meter.
Can you splice together colors? How would you make the lights change?
It is constructed more or less like coaxial cable. The wire has
2
conductors. Terminating the strand amounts to connecting the
conductors
together to form a circuit. Splicing should not be a problem.
I had the chance to speak to one of their engineers once for about a
half
hour. I ~wish~ I could remember his name. Anyway, he explained
to me
that they have a blue-green wire which will change colors as the
frequency varies. He further explained that the blue-green was
the only
color which would do this. All of the other colors will simply
light
brighter or dimmer.
>>It comes in 6 different colors and costs 4 bucks a foot. You will
need a
>>circuit to drive it at 200VAC at 1200Hz. Sipex makes a nice SMT SOT-8
>>chip that takes only a couple of external components, all surface
mount.
>
>This is a clue only to how they decided to do it. SMT SOT-8
is a package
>type not a part #. See if you can get a part #. When I
get a chance,
>I'll try and look at a Sipex web site. It's probably a micro
power low
>voltage oscillator that drives some sort of step up device (cheap
>switchmode or IF transformer probably). Maybe the step-up's
already on
>the chip...
>
>Ok, it's later now - I've been to the web page. Sipex makes
>Electroluminscent Lamp drivers. I'm printing out some app. notes
right
>now. I'll look it all over. Yes, this seems like the way
to go if this
>stuff applies well to Live Wire (I'm sure it does). I know some
of this
>stuff is for watch dials but it looks like theres some others for
more
>power. I'll have to look over this data.
>
>>I have the feeling we'll be seeing a lot of this stuff in '99, should
be
>>fun to see what people do with it. Hint: Moto HC05's are cheap and
have
>>alot of pins that can be pulsed.
>
>Hmmm, I'm pretty sure he/she's referring to a *series* of Motorola
CMOS
>low voltage digital parts but I'm not sure. HC05 alone is not
a good #
>I'm pretty sure....
>
>As far as sequencing goes, simple logic gate based circuits are probably
>the easiest thing unless there's a Gigsvillian who's really quick
with
>something like the Basic Stamp. I'm guessing tho that for each
"switched
>segment" of wire, there should be a separate little power supply (which
>probably isn't as bad as it sounds specially after seeing the Sipex
>stuff). I say this simply because it *may* be a pain to switch
200V even
>when there's almost no current involved (I've never tried it). I'd
love
>to see a schematic for some of the switched stuff from last year just
>Someone also mentioned that they sell 4 different types of inverters
- I
>was curious if there were inverters wherein the frequency could either
>be manually (or ideally, programmatically) altered. I'm a programmer,
>but don't have much electrical experience, but I'd love to have a
system
>where I could have the frequency altered based on a program, or some
>other external signal. Any ideas?
The Q&D way would be a monolithic voltage to
frequency converter
(the old 9400CJ comes to mind) fed from a slow speed DA converter or
a switchable set of function generators. Strobe like effects
could be
possible with square or staircase waveforms. Alternately a random
noise
chip would make the light vary, well, randomly ;-)
The outer shell seems to be clear PVC, so it can't take extreme heat.
The phosphor doesn't seem to be too affected by the heat from a
soldering iron.
Another tip: The best way I found to strip this stuff is to use
needle
nose pliers. Grip the wire 1/4" from the end with the tip of
the pliers
and pull. This removed both the inner and outer plastic coatings,
leaving the two fine outer wires intact. The easiest way to connect
to
the finer outer wires is to use a small strip of copper foil wrapped
around the outer case near the stripped section. Fold back the
outer
wires over the copper foil and solder them to it. This gives
you a
solid base to which you can attach the power leads to the very fine
outer wires. Take note, this stuff can bend, but not too much.
The
problems that we ran into most were shorts caused by excessive bending
of the wire.
You can splice it together like any other wire.
Wally Glenn wrote:
>
> Can you splice together colors? How would you make the lights change?
>
That's an interesting comment on the color. I found that there
is a
notable color change with all of the wires. It was more pronounced
with
the blue/aqua though. I think that it's like that because it's
the base
color. All of the other colors are derived by coating the wire
with
another color.
> I'm guessing tho that for each "switched
> segment" of wire, there should be a separate little power supply
(which
> probably isn't as bad as it sounds specially after seeing the Sipex
> stuff). I say this simply because it *may* be a pain to switch
200V even
> when there's almost no current involved (I've never tried it).
I'd love
> to see a schematic for some of the switched stuff from last year
just
It's not too difficult to switch those voltages.
If you want to take a HV DC power supply and produce switched HV AC
from it,
you can do it with 2-3 high-voltage transistors per circuit if you
use a
double-ended HV power supply (which is easy: two diodes and two capacitors
on
the output of an inverter) or 4-6 HV transistors on the output of a
single-ended power supply. This approach has the advantage that
you can
control the frequency and duty cycle of each segment individually,
for color and
brightness variation.
If you want to take the output of a HV AC power supply and switch it
to various
segments, use reed relays (cheap and good for millions of cycles),
solid-state
relays, or just a triac. Triacs and some solid-state relays will
only work if
there is a brief off period in the inverter output while it changes
polarity.
If you're designing your own inverters, that's easy to arrange.
If
not, you
need either a rectangle wave or sine wave inverter, not a square wave
inverter.
Another approach is to use a single high-power low-voltage double-ended
inverter driver connected to a bunch of inverter transformers, with
each
segment enabled by selectively grounding the other side of a transformer's
primary winding with a triac or high-power MOS transistor. This
avoids any
high-voltage switching, at the expense of one transformer/segment.
It also
lets you select the voltage for each segment individually.
If you have lots of segments and don't need varying voltages/frequencies
for
them, I think the triac-switched HV AC output will end up being the
cheapest,
simplest way to go. If you're tricky and add a delayed turnon
synchronized
with the AC drive, you should be able to dynamically control the brightness
too.
>It burns out. At 60hz (household) it'll lose 1/2 it's luminosity
in
>about 7 years of continuous use. At higher frequencies, this
is much
>faster. At 2000hz it's still in the range of hundreds of hours
and the
>stuff is quite bright.
Here's a question that hasn't been asked before:
How does lifetime
and brightness vary with the type of driving waveform? I'm thinking
of
the 'modified' sine waves put out by most inverters nowadays.
> > Could anyone on this list supply me with their proven circuit designs?
>
> I'm not on the list, but I've got a proven design :) We've
improved a bit
> on the 12V circuits that we used last year on the horse and other
costumes.
> We have eliminated some bulk by switching the high voltage side with
triacs
> instead of switching the 12 volt side. I'm just now moving
out of the bread
> board stage and tomorrow I should have a prototype PC board to test
with.
> These are very simple designs. The hard part, of course, is
the software
> and wiring labor.
>
> Anyone interested in one of the little boards should email me.
I can give
> you a schematic or if there's enough interest in these little boards,
the
> price goes down with volume just like the wire. I'll be making
a bunch of
> these so I can include anyone who wants some boards.
>
> We're still using 12V fixed-rated inverters designed to operate within
a
> given range of wire length. My next goal is to redesign the
inverter and
> integrate it into my switching circuits. If there are any magnetics
people
> out there interested in tackling this project I'd like to talk to
them.
>