Well- I would re-think that...
at 60 Hz, an AC 1/2 wave is only 8.333 mS long. Since we regularly turn them
on with non-zero-crossing devices at any point on the 1/2 wave that we want,
your answer has to be much smaller than 40mS.

If the triac were used with a zero-cross firing circuit as a simple static
AC switch, it could delay turn on by 8 ms or so. If it for some reason
didn't gate and latch, an appropriate gate control method may hold the gate
signal until it does latch, such as that used by the atmel gate chips. So
while it is conceivable that several 1/2 cycles could go by before the
device stays on, this would be due to a design flaw - not device
characteristics.

If it were random or phase-angle fired in a perfect world, it should turn on
instantly. Gate capacitance and all else aside. Otherwise the 3 uS quote is
pretty accurate....

You know the old saying about BS, right???!!!!

Chris

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of John Pearson
> Sent: Thursday, April 24, 2003 12:03 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE]: Triacs, turn on characteristics
>
>
> I should get straight to the point, while all the info is
> very helpfull too.
>
> What would be the longest possible time it would take to turn on an
> incandecsent 150 watt bulb with a triac controlling 110 volt
> 60Hz current.
> Somehow I figured it could be as long as .040 secs. This is
> assumming a
> perfect light bulb, that would illuminate instantly and a
> perfect triac,
> that would turn on instantly.
>
> Thanks
>
> John
> ----- Original Message -----
> From: "Michael Reid" <mikecreid@MSN.COM>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Thursday, April 24, 2003 8:38 AM
> Subject: Re: [EE]: Triacs, turn on characteristics
>
>
> > there are some great TRIAC tutorials on the teccor web
> site, on ST's web
> > site, as well as other manufactures of TRIAC's.  Most TRIAC's are 3
> quadrant
> > devices.  Teccor also has sensitive gate TRIAC's that can
> be triggered
> > directly from I/O's of some microcontrollers, using an
> inexpensive diac
> vs.
> > opto isolator.
> >
> >
> >
> >
> > On Thursday 24 April 2003 08:13 am, John Pearson wrote:
> > > How fast are generic Radio Shack triacs for switching 110v 60Hz
> > > current to...say...a 150Watt incandecsent light bulb.
> >
> >
> > > When the triac is enabled, where on the AC wave form will it turn
> > > on? Anywhere?
> >
> > You don't "enable" a triac, you turn it on. And it turns on within a
> > very short time (a few usec) of turning on the trigger current.
> >
> > > How about turning off, as I recall, the AC needs to cross zero for
> > > a triac to turn off?
> > >
> > > Thanks for any help. I am in a real pickle here. Got caught BSing
> > > on a forum and need to do some damage control. ; )
> >
> >
> > --
> > Ned Konz
> > http://bike-nomad.com
> > GPG key ID: BEEA7EFE
> >
> > --
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