Hello everyone,

I'm now working on constructing a device that can sense various light properties (hue, saturation, color temperature, etc...) in a team of four. The device has to sense incident light in some way and then calculate various light properties and send them to a PC via USB and then PC software has to pinpoint a position on a color graph of the incident light color.

For the color sensing circuitry, I must use Kingbright KPS-5130PD7C RGB color sensor, which is just a glorified array of 3 photodiodes (R, G and B) with a common cathode.

I'm trying to wrap my mind around some photodiode concepts, so I'm wondering if what I'm understanding so far is correct.

Photodiodes can operate in two modes, photovoltaic and photoconductive depending on their biasing. In photovoltaic mode, the diodes will output a voltage proportional to light intensity and they need no biasing. In photoconductive mode, diodes need to be reverse biased and then they will let a small photocurrent through which is proportional to light intensity.

Since the KPS sensor in photoconductive mode lets TINY currents through (micro amps) it would be hard to sense these small currents, amplify them and convert them to voltages and then send them to a microcontroller for processing without losing a lot of accuracy, i've decided to use the KPS sensor in photovoltaic mode and sample the voltages directly.

So if I don't bias the sensor, and then shine various lights at it while looking at the voltages across it's terminals, i should see those voltages change proportionally to the light intensity. Is this correct?

I have the sensor, but since its an SMD component it is too tiny to put on a breadboard and play with. Any ideas how to get an SMD component on a breadboard? Solder it to a piece of veroboard perhaps?

Thanks,
-NSKL

 

hi,
You should get a photovoltage prop to light over the range of the photodiode.
In the order of 0v thru +0.4v, this will of course depend upon the PD spec.

You can buy carriers for the SMD devices, not cheap, artwork your own or use strip board.

http://www.solarexpert.com/GlossaryPV.html

http://books.google.co.uk/books?id=0...sult#PPA177,M1

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Eric
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