Re: Re: Led lights

["Frank Mc Alinden" <fmcalind@xxxxxxx>]

Thanks for the info David....

Had a quick look inside my only x10 app module ...didnt realise that was an
impulse relay (also have  been called a clutch relay).....

frank


----- Original Message -----
From: "David Buckley" <db@xxxxxxx;
To: <ukha_d@xxxxxxx;
Sent: Saturday, February 07, 2004 10:33 AM
Subject: [ukha_d] Re: Led lights


> I've just had a quick shuftie inside an AM12
>
> The AM12 uses a (single pole) pulse (sometimes called impulse)
> relay, rather than a conventional relay.  Thus each time a control
> pulse is applied to the relay coil, the relay changes state.  The
> single pole switches the live line.  This is quite clever, as it
> minimises the power consumption of the thing, reducing the heat
> buildup.  (The relay uses a mains voltage coil, which is pulsed by
> an SCR)
>
> The corollary of using a pulse relay without an additional
"state"
> monitoring contact is that the electronics has no way of knowning if
> the relay output is on or off.  Which is bad, because (for example)
> when you go "all units off" you expect the appliance module
to
> either (a) If its on go off, or (b) if its off, stay off.  Just
> flipping state on principle would lead to some units going on, which
> is not at all what is intended :-)
>
> The solution embodied is to sample the mains output through a
> resistor, and so when the relay is on there is voltage on the sense
> resistor, and when its off, there isnt.  Thats the 80K explained.
>
> And I suspect if you chop the brown wire which supplies the sensor
> resistor (insert bomb defusing joke here) the device will change
> state once and then be confused forever.  I cant test that, as this
> particular AM12 (the only one within 10 miles of this keyboard) is
> ferked, having died within a week of being used.
>
> So, I cant see any good solutions involving simple hacking of an
> appliance module.
>
> Even so, this 80K would only allow 3ma to pass, which isnt much
> juice, representing a mere 0.75W.
>
> Solutions - all ugly.  External mains operated relay, with true dry
> contacts supplying your LEDs.  Or use a universal module to switch
> the low voltage side.
>
> Dig at X10 time:  Whilst trying to find the name of the universal
> module ('cos I'd forgotten) I was looking up www.smarthome.com,
> which I find to be a really handy informative site.  And they ship
> internationally.  But I digress.  I just loved this user comment
> about the Universal Module:
>
> "...I have used these for lawn sprinkler controls with approx 99%
> reliability."
>
> And thats why I hate X10.  It *almost* works...
>
>
>
>
>
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