Hi Sean,

Probably fine if driven with 50% duty cycle. The output from the EL-wire
definitely is suboptimal with or without a blocking capacitor when
driven from the asymmetric output of a photoflash or flyswatter
inverter.

Cheerful regards, Bob

On Sun, Nov 22, 2015, at 12:56 PM, Sean Breheny wrote:
> Bob,
>=20
> What about a DC-blocking capacitor?
>=20
> Sean
>=20
>=20
> On Fri, Nov 20, 2015 at 12:35 AM, Bob Blick <bobblick@ftml.net> wrote:
>=20
> > Hi Neil,
> >
> > No, square wave is OK. But if you have a DC source and you want an AC
> > square wave, you either need 3-terminal DC (positive, ground, negative)
> > and two switch elements, or an H-bridge. Either one will allow you to
> > alternate positive and negative excitation of your EL-wire. DC or DC
> > switched on and off will rot your EL-wire.
> >
> > Removing the rectifier from a photoflash and taking the output straight
> > from the transformer will be sub-optimal. The positive and negative
> > voltages are not balanced because the transformer is driven by one
> > transistor(with corresponding weird duty cycle. It will work OK but is
> > hard on the EL-wire, which doesn't last all that long anyway.
> >
> > Best regards, Bob
> >
> > On Thu, Nov 19, 2015, at 09:13 PM, Neil wrote:
> > > Oh, you mean sine-wave then I guess?
> > >
> > >
> > > On 11/19/2015 11:40 PM, Bob Blick wrote:
> > > > Switching it on/off is not AC.
> > > >
> > > > BB
> > > >
> > > > On Thu, Nov 19, 2015, at 07:14 PM, Neil wrote:
> > > >> Hi Bob,
> > > >>
> > > >> I was suggesting that I'd generate DC with the LED driver and then
> > > >> switch that on/off rapidly to get the 1KHz-2Khz AC (though square
> > wave).
> > > >>
> > > >> Cheers,
> > > >> -Neil.
> > > >>
> > > >>
> > > >> On 11/19/2015 12:46 AM, Bob Blick wrote:
> > > >>> Hi Neil,
> > > >>>
> > > >>> I've experimented a bit with this, and one thing I found is that =
EL
> > wire
> > > >>> really likes AC, like push and pull that is fairly well balanced.=
 DC
> > and
> > > >>> chopped DC don't work very well.
> > > >>>
> > > >>> Best regards, Bob
> > > >>>
> > > >>> On Wed, Nov 18, 2015, at 08:59 PM, Neil wrote:
> > > >>>> So I've got an EL driver that I want to use for a wearable, but =
it's
> > > >>>> bulky for that purpose, and I need something very thin.  Seems t=
he
> > > >>>> battery and transformer are the larger parts of the whole driver
> > > >>>> module.  I decided to redesign it with a LiPo, but it seems that
> > all the
> > > >>>> EL driver circuits I'm finding have transformers.  The EL-wire s=
pec
> > is
> > > >>>> 90-120V at 1Khz-2kHz.  Couldn't I use a high-voltage LED driver =
for
> > this
> > > >>>> purpose?  Something like Fig 8 here...
> > > >>>>
> > http://www.monolithicpower.com/DesktopModules/DocumentManage/API/Docume=
nt/getDocument?id=3D3473
> > > >>>>
> > > >>>> I'd still have to throw an oscillator in there to modulate the L=
ED
> > > >>>> driver, so I'll have to experiment to see if the LED driver can
> > switch
> > > >>>> on/off that quickly.
> > > >>>>
> > > >>>> Anyone know of a simpler way to do this?  Or maybe even a very t=
hin
> > (say
> > > >>>> few mm tall) transformer that can work for this purpose?
> > > >>>>
> > > >>>> Cheers,
> > > >>>> -Neil.

--=20
http://www.fastmail.com - Accessible with your email software
                          or over the web

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.