EL Wire Driver Interference

[Colonel Monk]

Howdy

It goes without saying that most of us have noticed the bleeping whine of an EL wire driver. Some are quiet-ish, but only drive a small amount of wire.

For this year, I had my chinese rickshaw out on the play and its crown jewel was a 2.5 foot wire sculpture of a dragon head - covered with EL wire!

The problem I had was that the 12V inverters are freaking noisy! Even the little inverter itself made an audible noise from several feet away, let alone the fact that the speaker wires / amplifier picked up the signal and amplified it - yeah the rickshaw has speakers....

So what do you all do to combat this? Obviously, we would try to keep the wires isolated but it seemed that the interference may have also come thru the common power source? I tried wropping the inverters (drivers) in tin foil and grounding it (playa fix) but that didn't work either.

Thanks,

CM

[dragonfly Jafe]

try an RF choke?

[Colonel Monk]

yEAH maybe - you think put it on the output of the inverter? Wouldn't make sense I guess to put it on the DC supply. ... Anyone?

[junglesmacks]

I'm thinking that the guys at Cool Neon would be pretty knowledgeable about this.. have you tried asking them?

http://www.coolneon.com/index.html

[uski]

I can help you but I need to know :
1) What was the power consumption of the inverters ?
2) What was the approximate frequency of the noise ? (very approximately! 200, 500, 1000, 2000 Hz...)
3) Are you sure the inverters you were using were designed to drive the length of EL wire you were using ?

[Token]

The problem lies with cheap drivers. The sad truth is that you are unlikely to find anything out there but the cheap stuff.

El Wire runs on AC 110V 1-4kHz. We are really good at hearing those frequencies.

The noise comes from the little transformers in the driver. It is a mechanical effect of the thin iron plates of the cheap transformer vibrating. Shielding with foil won't help.

Unless you are willing to build your own driver with quality components (lots of schematics available on the net), best bet is to put all the drivers in a sealed padded box with small holes for the leads.

Good Luck.

[gyre]

Lead foil is available.
Sheet is harder to find.

Dandy for acoustic isolation.

Mu metal is good for shielding, available as foil.

[Colonel Monk]

I can help you but I need to know :
1) What was the power consumption of the inverters ?
2) What was the approximate frequency of the noise ? (very approximately! 200, 500, 1000, 2000 Hz...)
3) Are you sure the inverters you were using were designed to drive the length of EL wire you were using ?

Sorry, I fell down on the job with my thread!

1) don't know the power consumption - I'm guessing in the mA range though. It was connected to a 130Ah battery.

2) The inverters I have are 2kHz.

3) Yes. They were designed from 20-50 ft.

http://www.coolight.com/category-s/29.htm

IFW 5681 2K 12v 20-50ft AND
IFW 5768 2KS - STROBER 12v 20-50ft

Hmmm. Now that you mention it, the strobing one I may not have had 20 feet.

Why are they different frequencies? I have some drivers (battery powered) that don't make noise, and I have some that are terrible - like these.

I had planned to have more EL wire on my intergalactic rickshaw but ended up just getting my dragon head sculpture done and then maybe 20 feet of purple on the frame.

I'm almost certain the strober didn't have 20 feet on it.... The "always on" one definitely had more than 20, and likely had close to 40 feet.

Thanks!

CM

[Colonel Monk]

The problem lies with cheap drivers. The sad truth is that you are unlikely to find anything out there but the cheap stuff.

El Wire runs on AC 110V 1-4kHz. We are really good at hearing those frequencies.

The noise comes from the little transformers in the driver. It is a mechanical effect of the thin iron plates of the cheap transformer vibrating. Shielding with foil won't help.

Unless you are willing to build your own driver with quality components (lots of schematics available on the net), best bet is to put all the drivers in a sealed padded box with small holes for the leads.

Good Luck.

Thanks Token - I hadn't thought of doing my own since they are so cheep. But I suppose it wouldn't be that difficult. I do have some experience building my own kit amps and such.

What makes the biggest difference, the quality of the transformer?

[bud buddah]

This is totally out of left field, but it might work if you can actually open the driver and see the transformer. If it really is just physical vibrations (which makes sense) could you dip the whole thing in some elastic coating, to hold things in place. I'm thinking of that stuff you use to dip tool handles in. It might be a whole lot easier than building one from scratch.
Bud

[bud buddah]

This is totally out of left field, but it might work if you can actually open the driver and see the transformer. If it really is just physical vibrations (which makes sense) could you dip the whole thing in some elastic coating, to hold things in place. I'm thinking of that stuff you use to dip tool handles in. It might be a whole lot easier than building one from scratch.
Bud

[gyre]

The term is conformal coating for the wire.

May help for noise.

I like the silicone spray.

[Token]

Thanks Token - I hadn't thought of doing my own since they are so cheep. But I suppose it wouldn't be that difficult. I do have some experience building my own kit amps and such.

What makes the biggest difference, the quality of the transformer?

It's real simple. Use a 555 timer to drive a transistor and a transformer with a current limiting resistor or somesuch. Might have to match impedance and deal with the capacitance in the wire.

Plenty simple schematics available.

How the heck you here the driver buzz over the Playa noise is a much more interesting question.

[Colonel Monk]

This is totally out of left field, but it might work if you can actually open the driver and see the transformer. If it really is just physical vibrations (which makes sense) could you dip the whole thing in some elastic coating, to hold things in place. I'm thinking of that stuff you use to dip tool handles in. It might be a whole lot easier than building one from scratch.
Bud

The whole driver is potted in epoxy already. No can open....

[Colonel Monk]

Thanks Token - I hadn't thought of doing my own since they are so cheep. But I suppose it wouldn't be that difficult. I do have some experience building my own kit amps and such.

What makes the biggest difference, the quality of the transformer?

It's real simple. Use a 555 timer to drive a transistor and a transformer with a current limiting resistor or somesuch. Might have to match impedance and deal with the capacitance in the wire.

Plenty simple schematics available.

How the heck you here the driver buzz over the Playa noise is a much more interesting question.

Thanks.

Yeah that's just the thing - the interference is amplified thru the sound system! So the 2 X 200W amp was amplifying the noise.

[Token]

Doh! How did I miss that part!

If your sound system is picking it up it's a different problem from what I was writing about.

Shielding and fixing the driver may help a bit but the main culprit is the wire itself. Huge antennae they are and you can't very well wrap them in foil.

Possible solutions:

Switch to CCFLs. More light but are rigid and 24" max length.

Wrap elwire with hair-thin wire such that the gap on the winding is at 1/4 wavelength of the driving frequency. Ground this shielding wire. This is a labor heavy way to go so test it before you invest the time and effort.

Ground and shield the audio equipment and cables. Ground the generator as well.

Actually, do a test at home. Plug the audio gear into municipal power where you know the groud is good. Run the elwire and see if it picks up the buzz.

[Snow]

sounds like your interference is electrical not audio. But I have heard this tip to get rid of the audio noise (which btw you can't hear really when on playa). Open up the driver and coat the transformer with hot glue. This gets rid of that annoying hum. I haven't tried this myself since I don't notice when on playa, but it can be maddening in other settings.

[tomasz]

Hey guys,

I was hacking around tonight with my EL wires and noticed something very similar, but the difference is that the audio system that picked it up was my smartphone's hands-free headphones/microphone (the person on the line also heard it). What's more is that the sound got louder as I put my hands closer to the actual EL wires. Not sure what that means, but it suggests that it's actually the EM field around the wires that's causing the interference, and not just ground interference.

[gyre]

The ballast is probably running at 110 vac or higher and 2-4kHz, according to one site.

So rf is a real possibility.