If this works it would be great.  There may be variations in EL wires,=20
so I'm going to give this a try as I see there are versions that go to=20
299, 360 and 400Vp-p.  I read something about someone varying the=20
frequency and getting a variation from green to blue, so perhaps there's=20
some tolerance there.  But from what I've read so far, to control=20
brightness, you'd have to vary the voltage.

I'll look at the internal functional diagram to see if I should bother=20
doing it with discretes.  If anything, it may be a good learning experience=
..

Thanks,
-Neil.



On 11/19/2015 3:49 AM, William Westfield wrote:
> There are special-purpose chips aimed at backlighting in=20
> wrist-watches. (Huh. Microchip even has a line; it looks like they=20
> must have acquired Supertex!=20
> http://www.microchip.com/ParamChartSearch/Chart.aspx?branchID=3D9020 ) I=
=20
> experimented with some of these quite some time ago, and discovered=20
> that they are not really very well matched to EL wire requirements;=20
> both voltage and frequency tend to be too low, and total power is low=20
> as well (they=92re designed for a square inch or two of EL panel at +/-=20
> 80Vp-p and 400Hz, while EL Wire would like 2kHz @110Vrms (~300Vp-p))=20
> However, the =93operational description=94 looks like something that woul=
d=20
> be implementable in discretes. The usual circuit is a pretty=20
> conventional inductor-based boost circuit (and you can get really tiny=20
> inductors for watches/etc) to generate high-voltage DC, followed by a=20
> HV H-bridge to generate =93AC=94 at a frequency that is independent of th=
e=20
> boost circuit switching freq. At one point, I was thinking that having=20
> microprocessor control over the AC frequency was the ideal way to=20
> control EL brightness, and I designed a circuit and PCB that would let=20
> a PIC or AVR do all the work. But I never got around to actually=20
> building it, so I couldn=92t say whether it actually works=85 These days=
=20
> there are also some tiny IC aimed at charging caps for Xenon flash=20
> circuits (and extra tiny transformers to go with them.) That might be=20
> another possibility. BillW=20

--=20
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