On 06/08/2012 01:35, Arfa Daily wrote:


"David" wrote in message
. uk...
On 05/08/2012 13:22, Arfa Daily wrote:
Hi all. Has anyone seen / used a 'light' switch that is just momentary
rather than latching like a normal switch ? I'm sure that somewhere in
the dim distant past, I have seen something that looks exactly like a
single gang flat-plate rocker light switch, but is actually spring
loaded back to the 'off' position. Or am I just imagining this in a
senior moment ? I've looked all through the Tool Station catalogue, but
nothing springs out at me.

Help confirming that they exist, or pointers to one, anyone ??

TIA

Arfa

I have lights that use a momentary switch in some labs at work,but the
switch is connected to a controller that uses the momentary output to
toggle the state of the light.Other inputs come from PIRs so the
lights go out when the area is unoccupied.

So,yes this type of switch is certainly available.try the MK Grid range


cheers

David


Similar sort of thing here. I have just replaced the shower extractor
fan / light, the original having a motor that wouldn't run any more due
to collapsed bearings. The reason for this is that in its 'standard'
form, the fan is controlled from the lighting switched live. That means
that the fan always runs if the lights are on. The shower room is at the
top of the stairs, and its lights cast a gentle light in the area
through the fanlight over the door, so tend to get left on all evening
until I finally go to bed (usually very late !!) and turn them off. So
I've done a mod to the new one, and designed and built a little
controller that senses when the shower pump motor is drawing current,
and produces a DC voltage to drive a mains-rated relay that I managed to
fit inside the fan run-on controller's casing. This means that the light
on the fixture can just come on normally from the switched live, along
with the other lights in there, and the fan won't run. When the shower
is used, the fan starts, and runs as long as my sensor circuit detects
that the pump is running. When it stops, the relay drops, and the run-on
timer takes over to continue extraction for a few minutes. An added
advantage of this is that in the summer when people take a shower
without putting the lights on, the extraction will still come on.

You can get either fans with humidistats, or standalone humidistats to
do much the same job. ;-)

I want the momentary switch to mount outside the shower room to bridge
the relay contacts. That way, if I want extraction without the shower
running (there's a bog in there as well, so use your imagination ... )
I can just stab the switch, which will start the extractor fan. It will
then run for the run-on time controlled by its own timer. It does all
work exactly as planned, and I have the wire running down the inside of
the airing cupboard which is next to the shower room, so all that's now
needed is to bring it through the wall, and obtain and connect the
switch :-)

Yup, that's handy.


--
Cheers,

John.

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