Re: Making an X-10 lamp module immune to dimming

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"isw" <isw@xxxxxxxxxxx> wrote in message
news:isw-B62626.10184909062008@xxxxxxxxxxxxxxxxxxxxxxxxx
<stuff snipped>

>> Are there other devices that can interrupt current flow with a gate
>> trigger?

> Yes. There are gate-turn-off (GTO) thyristors:
> http://en.wikipedia.org/wiki/Gate_turn-off_thyristor

So that's how my auto-thyristor flash works!

> > > Right on. But think about how a half-sine looks -- a linear increase
in
> > > on-time does NOT result in a linear increase in power delivered to the
> > > load.
> >
> > Right.  This looks very much like an "area under the curve" sort of
problem.
>
> Close, but more complex, because the load (assuming an incandescent
> lamp) is not constant. The resistance of a lamp filament is lowest when
> it's cold (which is why a burn-out so often occurs when it's switched
> on), and rises as the filament heats up.

I see
>
>>>> So it might even be possible it's really just noise with no particular
>>>> function but no particular harm to the operation of the module.
> > >
> > > It's not noise; it's a regular string of pulses.
> >
> > I thought that any signal other than the one you wanted could be
> > considered noise.
>
> That's a simplistic definition, although it sometimes works.

I'm a simplistic guy.  (0:  I assume the anything that is non-random
shouldn't really be called noise.

>>> I didn't care about repeaters. What I wanted to do was control a large
>>> number of electrical valves for an irrigation system. As I said, the
>>> problem was that it was not repeatable -- the same number of "brighten"
>>> pulses did not always result in the same pulse width, and so I could not
>>> reliably select which irrigation circuit I wanted to run.
> >
> > Too bad.  What's a large number?  There's a lot of headroom with 256
> > discrete X-10 addresses, even if you're controlling a modern home.
>
> That National chip (an LED bar generator) has ten outputs, and it can be
> hooked up sort of like a ten-value A-to-D converter. Having to use an
> X-10 module for each and every sprinkler valve would work, but has even
> more problems -- not least of which is the tendency of the things to
> turn on for no evident reason ("noise" if yo will).

Indeed.  The only (marginal) solution for me is double-stacking modules.  So
far, only operator error has inadvertently activated something I've got
"double-stacked" appliance modules but I still would be reluctant to control
water valves without some other independent verification of operation.

> > <stuff snipped>
>> This sounds like one reason that circuit designers are always tweaking
>> the values of capacitors and resistors between board versions:  to
optimize
>> the various design trade-offs.  (-:

> Well, yes, but usually a *real* designer will have a good notion of what
> values to use and not have to try a bunch of things to see what works.
> Changing a board layout can slightly alter things like the capacitance
> between adjacent traces, and that can cause instability, especially if
> the original values were determined "experimentally" by someone who
> didn't understand worst-case design, margining, and so on.

Good point.

<stuff snipped>

> > It seems as if the R/C circuit is one of the most common electronic
> > "building blocks."
>
> Yes, it is. Both components are cheap, and easy to get in a wide range
> of values.
>
> Here's an interesting item: Of all physical units (weight, volume,
> current, voltage, heat, ...) resistance is available over by far the
> widest range, easily from under a micro-ohm to over a hundred megaohms
> -- say fourteen orders of magnitude. That's why electrical simulations
> of other phenomena are so easy.

And now there's a fourth basic component:  the memristor!  (The other three
are resistors, capacitors and inductors.)

"The newly discovered circuit element - called a memristor - could enable
mobile phones that can go weeks or longer without a charge, PCs that start
up instantly and laptops that retain your session information long after the
battery dies. It also could challenge flash memory:  the HP discovery would
be faster, use less power and take up far less space than today's flash."

http://news.google.com/news?hl=en&um=1&tab=wn&q=memristor&btnG=Search+News

--
Bobby G.