I'm trying to get an el sequencer to fade the el on and off ever so slightly, like the cathode in a vacuum tube warming up. No slower than 1/4 to 1/2 second of fade. Do you think a capacitor in series with the output would work? How many micro farads?
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Nevada
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Re: Fade on, Fade off
Mon, August 6, 2007 - 7:20 AMhmmmm........I don't know that it would work (though you can try)
it may be helpful for you to know, that electrically the wire is acting as a capacitor itself.
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Re: Fade on, Fade off
Mon, August 6, 2007 - 8:04 AMI think that this is actually rather hard, there have been discussions on this board about various solutions and none have been ideal. The output of the driver is high frequency AC so a capacitor won't work like it will in a DC circuit. You can try putting a capacitor across the DC input leads, try 1 uF and go up from there. Let us know what you find! -
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Re: Fade on, Fade off
Mon, August 6, 2007 - 9:33 AMAgreed, a capacitor is not going to work.
To have EL wire fade in and fade out, you'll either need to play with the voltage, or play with the duty cycle (PWM). I'm pretty sure that apparent brighness is not going to be linear with either votage or duty cycle, so you'd have to experiment to see what looks like a smooth fade. Not an impossible task, but not a trivial one either. -
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Fading.............
Mon, August 6, 2007 - 1:58 PM -
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Re: Fading.............
Mon, August 6, 2007 - 6:00 PMyeah, but I think there's a whole lot of circuitry behind that thing that makes it work (I've played with one of those units) as far as I know, it's not going to be easy to take an existing driver/sequencer and add a dimmer into it.
In fact, at the soldering party just on Friday, someone asked that very question, and the electrical tech head who answered the question said that it was a different circuitry than you'd find in most of the other drivers....the other drivers use the capacitance of the wire actually as part of the circuit, but that dimming driver did not. (doesn't quite make sense to me, but that's what he said.
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Re: Fading.............
Mon, August 6, 2007 - 9:53 PM -
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Re: Fading.............
Tue, August 7, 2007 - 11:07 AMI know some of the sound reactive inverters vary the brightness....
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Re: Fade on, Fade off
Tue, August 7, 2007 - 6:18 PMHatfield is correct, vary either the voltage or the duty cycle. I built a timer once to allow to me vary the duty cycle and pulse width of the wire and was able to get some pretty trippy effects. It was on a body suit and one person said it looked like the space around me was on acid when I moved and danced. For the fade in/out effect you're after I'd try varying voltage though, and I think you'll have better luck if you don't fade all the way off, just very dim.
on a tangential but related note: the aqua wire can color shift from blueish to greenish if you vary the frequency driving it. -
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Re: Fade on, Fade off
Tue, August 7, 2007 - 9:54 PMThanks, all. You all know some helpful stuff, and I appreciate that we can share it here. The project I completed last night is a two foot tall Nixie or Numitron tube, using bent coat hangers for letters/numerals and orange el fastened to it with clear wire loom. It's all housed in an acrylic dome used to house aircraft warning beacons so it looks like a giant vacuum tube.
The fading would have helped, but won't make it in time for Burning Man 2007.... but there's always 2008!
Here's an example of the slight effect I was going for:
www.youtube.com/watch
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Re: Fade on, Fade off
Fri, March 21, 2008 - 4:26 PMHey,
I've been messing around with EL now for awhile and have made a board for switching with OCTs. Now I am working on the inverter side of things, and one of the effects I implement is glow intensity control. In the current version I generate synthesized (stepped) AC wave-form and effect visual 'linearity' by indexing magnitude through a lookup table, --the kludge works fairly well up to the minimum flourescent cut-off voltage. Length also affects the upper-lower voltage range I've noticed. Maybe if not too complicated I could adaptively sense load and auto-scale the table at init? The problem I'm having is trying to find an appropriate transformer. I used the design article from CoilCraft, ("Structured Design of Switching Power Transformers") with appropriate parameter changes but their cores are too expensive for my application cost point, however, the design does work well.
I use an 18Fxxxx series PIC uController as the switch engine. The Chinese cores I've tested so far exhibit poor product quality control and roughly 1/3 don't work out of the same run, but they are really cheap.... I keep plugging on. Eventually I will (been working on this as time permits over the past couple of years now), eventually I will post all of my project details so people can make their own or buy kits from me?
Good luck.
Love - tron
