night light



We got this cabin in the mountains, and it's DARK up there at night.
The HOA forbids exterior lighting... I'd forgotten how many stars
there are.

We inherited a 4-poster bed that has huge klunky dark-varnished
turned-wood posts. If you get up to pee in the middle of the night,
chances are pretty good you'll walk right into one on the way back,
right at head level.

So I got a couple of clear plastic dome sorts of things at the
hardware store, intended for the legs of chairs to slide on carpet or
something. I painted them inside with strontium aluminate
glow-in-the-dark paint and set them on top of the bedposts. Not bad,
but they don't get charged up much in the afternoon - the room faces
east - and so they're very dim in the early morning hours.

Next idea: bore a hole in the top of each post and drop in a night
light made from from a AA lithium battery and a high-efficiency LED.
Some of the led's we use are visible in room light at 1-2 uA, so I'm
thinking maybe 5-10 uA would do for a post marker light. A Tadiran 3.6
volt lithium is good for about 2.5 A-h, or 250K hours at 10 uA, over
20 years. I could even hack in a photosensor circuit to shut it off
when there's ambient light, but that's hardly worth the effort.

I wonder which color LED would be most visible to dark-adapted
eyeballs at very low current.

Even cooler would be a couple of those tritium-powered light sticks.
They're available in the UK and asia, but are for some reason illegal
in the USA. Looks like some furrin' scofflaws will sell them on ebay
and ship to the US, so maybe I'll give that a try.

John




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