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light box intensity

libraryman

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libraryman

libraryman

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Hi all, having moved from a DSLR to a CCD camera, I find that my light box is way too bright for my flats..

What's the easiest way to reduce the intensity...I'm thinking of something like a small resistor type controller/dimmer?

I have tried to add material in front of the light but its still too bright!!!, i have also reduced the voltage but that did not work?

Ray

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libraryman

libraryman

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O.k Roger, i made the light box using white led bulbs that come in strips....not ideal apparently! But it appeared to work o.k.

The LED's are covered with several lamination pouches but clearly still too bright.

The light is 12volt...I tried less voltage but no light comes onap at all!

Ray

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nightster

nightster

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JAS is correct. Those PWM controllers are great. I built my dew heater controller from one of these and now I am building a LED light box and simply using my dew controller to dim the LEDs. I am also using a spare channel on the PWM controller to dim a strip of red LEDs used to illuminated the laptop keyboard inside my blacked out PC box (a black plastic storage box layed on its side to keep stray laptop light away from scope or dark adjusted eyes and to keep dew from my laptop.) I might add some red LEDs to the outside of the box to illuminate the rig when night adjustments are needed.

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perfrej

perfrej

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I just read the top post again. The LEDs do not dim with reduced voltage, so they are driven in switched mode. If you wave them rapidly back and forth they will show broken light traces to your eyes, not solid ones. Adding another PWM in front will most likely damage the circuitry that handles the switching.

So, if you have broken light traces when you wave them, or if you can check some other way if they are indeed rapidly switched on and off, perhaps alternating between diode banks, you need to find out how the circuitry works before you add a PWM in front!

Another question; if it doesn't dim when you lower the voltage manually, how could it dim if you do it with a limiting box instead, PWM or linear?

Not trying to be rude; just making sure you do not burn the thing to pieces :)

/per

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libraryman

libraryman

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Sorry for the late reply, been away for the w/e!

Thanks /Per for the advise, you might gather that i am not electrically biased, all i can say is that they are powered by my Maplin regulated Dc power supply!

I'll try to check the idea behind the broken lines and come back

Ray

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nightster

nightster

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I just bought a 15 meter roll of LEDs for like 4 US dollars. The cost of a nice coffee. The strips seemingly have some electronics built into them. Every third light is a contact area that can be cut with scissors and this is where you attach the contacts that have the wires to power them. I have never seem these lights before they are really amazing. Some have a clear flexible rubber coating that makes them weather proof. I can take some more detailed photos and some macros if you would like. I want to string these lights all over the house as they are seemingly very energy efficient.

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perfrej

perfrej

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Me Penrice, when it comes to dimming flat light sources, I'll second any cloth, paper, plastic, filter or frosted glass solution in favour of anything electronic. Mind you, this is a one-off situation ;)

/per

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ollypenrice

ollypenrice

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Me Penrice, when it comes to dimming flat light sources, I'll second any cloth, paper, plastic, filter or frosted glass solution in favour of anything electronic. Mind you, this is a one-off situation ;)

/per

I'm going to get this printed on paper and ask you to sign it, Mr Frejvall! A non-electronic solution approved by Per???

I need to sit down...

:grin: lly

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perfrej

perfrej

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Sit down, have a beer, or rather French you have become, perhaps some Champagne? Funny - I just had a bottle of 2002 Legras & Haas with my wife and it was quite good. Slightly dimmer due to some cloth, but then again...

/p

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