Re: Controlling Holiday Lights

[sylvan butler <ZsdbUse1+noZs_0610@xxxxxxxxxxxxxxxxxxxxx>]

On Sat, 21 Oct 2006 06:38:10 +0000 (UTC), John Haskey <johnh@xxxxxxxxx> wrote:
> In article <slrnejfnul.uc9.ZsdbUse1+noZs_0610@xxxxxxxxxxxxxxx>,
> sylvan butler  <ZsdbUse1+noZs_0610@xxxxxxxxxxxxxxxxxxxxx> wrote:

> I agree that the parallel port is much faster but how fast is fast

My design threshold is 1000hz.  That seems to be fast enough to PWM
lights (remember that is 1000 on and 1000 off per second).

> enough?  Your relay is going to take ~8ms to turn on.  An incandescent

No, that is only for a zero-crossing detecting swith.  Typically those I
use for small lighting loads (a few amps) cycle in well under 1ms.  I
only use zero-crossing for larger loads (currently up to 40a) where that
characteristic matters, or where I don't need blazing speed.

> It depends on how many relays you are going to control and that's
> pretty limited unless you multiplex your parallel port.

Very.  12 on a standard parallel port, but only 8 of those are 'fast'.
That's why I was asking about multiple parallel boards.  :)

The PC is primarily the prototyping platform for sw development.  The
final target is a microcontroller that will either be autonomous
(little) or sit on an ethernet (big).

> Do whatever works.

Yup.

sdb
--
Wanted:  Omnibook 800 & accessories, cheap, working or not
sdbuse1 on mailhost bigfoot.com