On 8 Sep, 10:46, Recyclist wrote:
On 7 Sep, 20:17, "Bill Wright" wrote:





The cupboard has two doors, which open independently. The plan is to fit two
push switches of the type sold for this purpose, one for each door. The
switches will control a light that will shine into the cupboard, which is
rather deep and gloomy. These switches are 'on' when the plunger is out, so
the light comes on when the door is open. I also intend to use a timer so
that if the door or doors are left open the light will eventually go out.
The timer will commence timing when the supply is applied (the door(s) are
opened) and if the door or doors are left open the light will eventually go
out. If the doors are closed during the timing period the light will go out
immediately. In order to initiate a timing period and turn the light on the
door must be closed, then the timing period starts when the door opens. I've
sorted the timer out. It's a multifunction one, and it does what I want. But
ideally I'd like the light to come on if either or both doors are opened,
and stay on for the full duration of the timing period even if one of the
two doors is shut. With one door it's simple. The one switch controls the
timer perfectly. But with two doors and two switches the best I've done is
to have the switches in series, so that both doors have to be open to
initiate the timing period. With the switches in parallel, if one door has
been left open the timing period will not commence when the other door is
opened. It is necesssary for both doors to be closed, then either to be
opened. If the switches are in series, for the timing period to start one or
both doors must be shut, then both must be open.

Suggestions anyone?

Bill

I'd use a PIR sensor and a timer, or even a PIR sensor with a timer
built in.

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Or a photo-sensor, if it doesn't matter that the cupboard light won't
come on if it is dark and there are no other lights on nearby (which
doesn't seem too unreasonable).