Light monitoring LED circuit

[Ben Micklem]

Hi,

I'm very inexperienced and am looking for advise on how best to solve my
problem:
I need to illuminate a small area with white LEDs during daylight, and IR
LEDs during the night. The intensity of the white LEDs should go down as the
light fades, and the IR LEDs should slowly come on.

I will also be supplying power to a camera (5V 1.5A), so was thinking of a
2x5V transformer (from 240V mains). The LED arrays will each draw 120 mA. I
guess I need a light-dependent resistor and a simple IC to control this?
Both arrays should also be able to be turned on and off (not independently)
by an output from the camera. The output is described:
"With a maximum load of 100mA and a maximum voltage of 24V DC, this output
has an open-collector NPN transistor with the emitter connected to the GND
pin. If used with an external relay, a diode must be connected in parallel
with the load, for protection against voltage transients."

Any advice, or directions to a source on the web that could solve this
problem?


Ben

 

[Phil Allison]

"Ben Micklem"

I'm very inexperienced and am looking for advise on how best to solve my
problem:
I need to illuminate a small area with white LEDs during daylight, and IR
LEDs during the night.

** Errrr - this small area = the size of a shoe box ?

Or the size of a tennis court ?

Can you please be more vague.

It really makes our day.





........ Phil

 

[Ben Micklem]

On 28/11/07 06:30, "Phil Allison" <philallison@tpg.com.au> wrote:

"Ben Micklem"

I'm very inexperienced and am looking for advise on how best to solve my
problem:
I need to illuminate a small area with white LEDs during daylight, and IR
LEDs during the night.

** Errrr - this small area = the size of a shoe box ?

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

 

[Phil Allison]

"Ben Micklem"

I'm very inexperienced and am looking for advise on how best to solve my
problem:
I need to illuminate a small area with white LEDs during daylight, and
IR
LEDs during the night.

** Errrr - this small area = the size of a shoe box ?

Or the size of a tennis court ?

Can you please be more vague.

It really makes our day.


It doesn't make any difference to the circuit-

** It makes a VERY big difference to us deciding if you are a lunatic or
not.

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.

** Shoe box - right ?

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.

** Hey - what a good guess I made !!!

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

 

[Ben Micklem]

in article 5r4o5tF12ksruU1@mid.individual.net, Phil Allison at
philallison@tpg.com.au wrote on 28/11/07 08:45:

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.


** Hey - what a good guess I made !!!

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.

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 white LEDs can just be operated by a timer surely

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).

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

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.

Simple solutions ARE best.

Give it a go.



...... Phil

I'm currently looking a circuits such as the one show at the end of this
article:
http://www.videsignline.com/howto/sensorsoptics/191000886

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

 

[Phil Allison]

"Ben Micklem"
Phil Allison at

** Hey - what a good guess I made !!!

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.

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 white LEDs can just be operated by a timer surely

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).

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

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.

** OK - first you have to get the basic physics right or nothing will
work out as you want.

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

 

[Ben Micklem]

in article 5r57i5F12mj1oU1@mid.individual.net, Phil Allison at
philallison@tpg.com.au wrote on 28/11/07 13:08:

The white LEDs can just be operated by a timer surely

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).

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

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.


** OK - first you have to get the basic physics right or nothing will
work out as you want.

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.

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

 

[HapticZ]

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

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:5r4o5tF12ksruU1@mid.individual.net...

"Ben Micklem"

I'm very inexperienced and am looking for advise on how best to solve
my
problem:
I need to illuminate a small area with white LEDs during daylight, and
IR
LEDs during the night.

** Errrr - this small area = the size of a shoe box ?

Or the size of a tennis court ?

Can you please be more vague.

It really makes our day.


It doesn't make any difference to the circuit-


** It makes a VERY big difference to us deciding if you are a lunatic or
not.


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.


** Shoe box - right ?


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.


** Hey - what a good guess I made !!!

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

 

[HapticZ]

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


"Ben Micklem" <benmicklem@hotmail.com> wrote in message
news:C373209D.45737%benmicklem@hotmail.com...

in article 5r57i5F12mj1oU1@mid.individual.net, Phil Allison at
philallison@tpg.com.au wrote on 28/11/07 13:08:

The white LEDs can just be operated by a timer surely

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).

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

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.


** OK - first you have to get the basic physics right or nothing will
work out as you want.

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.

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