Re: X-10 'Drop in' Lights switches

["the_home_automator" <db@xxxxxxx>]

>
> Why do the dimmer modules need a neutral anyway?
>

Dimmers are electronic devices and as such need power.  The only
question is how to get that power.

Many simple dimmers are installed in-line in the live wire, in the
same way as a conventional switch.  When the dimmer is off, its easy
to see there is 240v across the terminals of the dimmer, and thus the
dimmer can "rob" power.  As the lighting level increses,the
dimmer
operates as a switch, operating 100 times a second.  The briliance of
the lamp is determined by how much the switch is on.  As the
briliance increases, the power available across the dimmer terminals
reduces, to at 100% level, the dimmer is always on, and thus there is
no power available across the dimmer terminals, and thus the dimmer
cant work as it has run out of power.

Most dimmers thus only go upo to about 95% of full power, thus
allowing that last 5% to be robbed to power the dimmer.

To get to 100% level, you need to get power other than by robbing,
and thus a conventional power supply is needed, and hence a
"proper"
mains suply involving live and neutral.

Also, an X10 dimmer needs more power than a simple dimmer, and so the
robbing technques may not supply enough power.  Finally, there is the
minr matter that the X10 signal is across the live and the neutral,
and thus X10 detetion is a bit hard without the neutral as a
reference ...

David





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