Best way to detect light color or frequency for Prop based Spectrum Analyzer

Macore

I am wondering which sensor or technique would be best for determining light color or frequency with a Prop chip with the intent of making a cheap Spectrum Analyzer?

Both the ColorPAL and the TAOS sensors seem like they are orientated to the color of objects, not ambient light. Is this correct?

What about a Phototransistor or the Photoresistor? They seem like they only handle "white" light? The Blue-Enhanced Photodiode looks from the datasheet that it might be able to discern individual light components?

My plan was to use a Full Color LED that has RG and B lines, vary those with Digital Potentiometers to get some different base readings and then use 2 of the Light Intensity to Square Wave Frequency chips and compare the outputs?

Now I have every intent of doing some experiments to test some things and try them out, but I really don't want to buy a ColorPAL or the TAOS sensor only to find out they wont really do what I want. I already have some Photoresistors, the Diode and Light Intensity sensors...

Thanks for any help

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Often the joy is not so much in the having, its in the building...

Phil Pilgrim (PhiPi)

The ColorPAL can only be used with near-range reflective sources. The TCS3200-DB can be used with both reflective and emissive sources — the latter simply by leaving its LEDs turned off. Neither is a true spectrophotometer, though, as they both measure the color response in three broad RGB wavelength bands (much as the human eye does). A spectrophotometer, by contrast, uses a prism or grating, along with a linear image sensor, to measure the response at hundreds of different wavelengths. Such instruments tend to be very expensive.

What is your final objective with this? There is much you can measure with an RGB detector like the TCS3200.

-Phil

Macore

Well Phil, I wanted to have a Bot that could roam around and collect certain kinds of payloads based on the color (wavelength) of light that it was emiting. Then if it was a match pick it up and move it to a reserved area. I suspected what you said about the ColorPAL and the TCS3200-DB is kinda pricey (missed the sale the other day). You don't think I can get away with comparing a base light composed of RGB sources against the test light using the Light to Frequency Converter, or a Photo resister, transistor, diode, etc?

Thanks, will get the TAOS if its my best shot. I guess.

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Often the joy is not so much in the having, its in the building...

Phil Pilgrim (PhiPi)

How big and how bright will the payloads be? The TCS3200-DB is like a one-pixel color camera that includes a lens. To see an object, that object has to be within the camera's field of view. To detect that object's color, it will have to fill the field of view completely. And to locate such an object, you will have to scan the camera, either by mounting it on a servo-panned turret or by turning the robot itself. Will that work in your application?

-Phil

Macore

Well I was envisioning a sort of small box with say a Red, Green or Blue LED on top. A Boe-Bot roaming around would see the light form this box, drive over for a closer look and try to ID the color of the LED... So I am not sure really, this is all just a wild thought process at the moment... I thought about doing it with Sound too, but it seemed there is a plethora of visual sensors out there so it must be able to be done. If I have to I can make the Boe-Bot try to move around the box for an optimum position (if it is a Box), the Boe-Bot will be scanning for objects with a Ping sensor...

Crazy ideas, huh? Thanks Phil

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Often the joy is not so much in the having, its in the building...