Light monitoring LED circuit

"Ben Micklem"

Or the size of a tennis court ?

Can you please be more vague.

It really makes our day.

....... Phil

It doesn't make any difference to the circuit- the light sensor is monitoring daylight, not the LED light. As I said in the original post that I had LED arrays that draw 120mA each, I thought you would be able to guess the order of magnitude of the area.

It will be a range of boxes from 150 x 120 x 150 mm up to 200 x 200 x 400 mm. It is for a sealed camera and lighting module that can be moved between bird boxes, depending on which boxes are used or the timing of nest building/laying/hatching/fledging.

Ben

"Ben Micklem"

Now we know you clearly have a solvable problem - maybe even a rather interesting one.

You may be able to simply leave the IR source on 24/7 - I bet the birds will never know.

The white LEDs can just be operated by a timer surely ?

Any decent CMOS or CCD camera has enough automatic light compensation to cope.

Simple solutions ARE best.

Give it a go.

...... Phil

in article snipped-for-privacy@mid.individual.net, Phil Allison at snipped-for-privacy@tpg.com.au wrote on 28/11/07 08:45:

Thanks for your reply Phil. I'd rather the IR was not on all the time, as it gives a purplish tint to the shadows seen through the camera during the day. The camera doesn't have a movable IR filter (as most camcorders/security cameras do when they have a monochrome night mode- mine just drops into a monochrome mode when the visible light levels drop low enough) so the IR will get through to the sensor even during colour/daylight operation.

The idea is to provide a fill light- at the moment the spot of light coming through the hole is a burn-out blob moving across the inside of the box (or if you adjust the exposure, the shadows are too dark, and the spot OK).

I want the white LED light to adjust proportionately to the daylight so that the image still looks naturally lit, and so that on dark days the birds aren't disturbed by their nest being strongly lit. During full sun, the LEDs will have to be quite bright to fill in the shadows- this amount of light during a dull day would be very obvious to the birds.

I'm currently looking a circuits such as the one show at the end of this article:

I don't know how suitable those components are for my use- looks like they couldn't take being soldered by hand. Also, I need to have the IR LEDs fading when the white ones are on....

Ben

"Ben Micklem" Phil Allison at

Light coming from the sun is ** INCREDIBLY ** bright - easily 100 times that of most man made light sources ( carbon arc lamps excepted) .

Just try a torch or any domestic light out in the open, in average daylight, to see that fact.

I recommend you completely eliminate that " burn out blob " by screening direct sunlight from entering the box - ie erect a light shield.

Make the bird box fairly dim, like a room with the blinds drawn, so the white LEDs can in fact be the main light source.

Then a timer is all you need, one that switches the LEDs from white to IR.

...... Phil

in article snipped-for-privacy@mid.individual.net, Phil Allison at snipped-for-privacy@tpg.com.au wrote on 28/11/07 13:08:

Unfortunately, I am also bound by the basic rules that I have to follow as a wildlife photographer. Filming birds at nest is a very sensitive subject- any avoidable disturbance is unacceptable, and may be illegal. A bright LED illumination of the inside of the box suddenly coming on at dawn is an unacceptable disturbance. Even if it was faded in, the biorhythms of the birds would be affected by the lighting. If the breeding male didn't sing at the same time as his neighbours, his territory may be infringed, leading to conflicts when they should be putting effort into getting food. The chicks may not be able to judge the passing of time without minute day length changes, or may choose to leave the nest on a very dark, wet day, and so have much reduced chances of survival.

As for the light intensity- the fill light required is within the power of the 6 white LEDs- I have tested this with the camera. The inside of the box is not illuminated by full sunlight- it is in the shade of a tree (you don't want boxes to be in full sun- the birds won't choose to nest there because their young would be overheated, or eggs hatch before the parents decide to start incubating the brood).

Ben

birds want the lights on to breed their chicks? i thought they chose cozy dark places for a reason!

my

i concur, artificially illuminating them birds may be hazardous to their procreative health, and to the success of the project

just stick with the IR leds and be satisfied with a b/w image

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