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Old 11-15-2010, 10:02 PM   #46
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I got tired of the Hamamatsu runaround and by chance I was rechecking if alliedElectronics sold anything similar to that photodiode but don't have a minimum order.

They do
http://www.alliedelec.com/search/pro...0078#tab=Specs

So, I canceled my account with Hamamatsu and ordered this instead.
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Old 11-18-2010, 07:02 PM   #47
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I have been away a few days. Sweet, another new source for photodiode. Keep at it mistergreen.
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Old 11-18-2010, 07:46 PM   #48
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Yup, the new photodiode just arrived today actually.
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Old 11-19-2010, 01:02 AM   #49
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I soldered in the new photodiode. It took 10 seconds; a snap. It's reading my desk lamp and it looks good.

Now I need the sun to come out so I can set the maximum parameter.
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Old 11-21-2010, 12:25 AM   #50
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Ok, I got to make some readings


And this is the result.


So, toward the end there, it doesn't look like it falls off correctly. THe values are too high.
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Old 11-21-2010, 04:14 PM   #51
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I'm starting to think that cosine correction filter is pretty important to shift that line curve into place.
Readings can shift if I tilt the sensor slightly.
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Old 11-21-2010, 05:42 PM   #52
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mistergreen,
I think you are almost there. The graph seem to have the same order of magnitude.
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Old 11-21-2010, 09:14 PM   #53
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looks like its getting close!!! keep up the good work!
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Old 11-22-2010, 10:29 PM   #54
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I was looking around the web for a company that sells cosine correction filters. I finally found one but prices are a bit steep.

Quote:
T UV-Vis Internal Diffuser
$67
Used in addition to the W for improved cosine response, especially with thin film filters. For spectral ranges 250- 700nm.
TD Low Cost UV-Visible Diffuser
$67
Domed teflon diffuser for use with IL detectors for spectral ranges 250- 700nm.
W Quartz Wide Eye Diffuser
$144
Internal hemisphere of solid quartz for use with IL detectors for cosine response
A312 Opal Diffuser
$144
Opal Diffuser, Mounted in A310 Ring
A313 Flat Quartz Diffuser
$167
Flat Quartz Diffuser, Mounted in A311 Ring
A cheaper router would be go onto ebay and buy a cheap light meter and harvest the diffuser.


Or maybe look around hobby and art store for anything spherical and can act as a diffuser.
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Old 11-23-2010, 12:33 AM   #55
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Quote:
Originally Posted by aaronbrown View Post
this might help you all out at least to make the sensor http://www.colorado.edu/eeb/facultys...e_Daniel03.pdf
Oh! thanks to aaron, a sheet of opal acrylic will work as the diffuser. I think HD carries it..
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Old 11-26-2010, 05:04 AM   #56
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Well, it's harder to find opal acrylic than I thought. There are suppliers in China but I'm not going that route.

I used a regular piece of white plastic instead...



And the result is quite funny.


A linear line, no inverse law what soever . Very strange.... I'll have to remove the piece of plastic.

I did learn one thing though. My initial reading from the very beginning might have been affected by the tank and water... I remember reading where hoppy said the water and sides of the tank might act to reflect and magnify the light. I'll have to remove my light and test it outside the tank.
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Old 11-27-2010, 03:55 AM   #57
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Latest readings


Good nuff.... Now to go measure stuff. I have a feeling my 75G tank has too much light and that's the source of my minor algae issues.

Oh, I'll build a JAVA app that'll output the 'PAR' too. It's cross platform for anybody that wants it.
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Old 11-27-2010, 05:38 AM   #58
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That's looking good now, probably as accurate as you will need it to be. How did you get the data to fall where they do now?
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Old 11-27-2010, 05:51 AM   #59
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I took the white plastic off the sensor and measured the light outside the tank.

I noticed measuring in the tank full of water was giving me higher readings that didn't fall on the inverse law curve.

over all cost:
~$10 - photo diode + S&H
~$.50 - plastic paint cup
~$4 - electrical cord
~$30 - ardiuno MP (there's a $20 version too, and there's a $5 texas instrument one)
~$.50 - 27K resistor

total: $45.00
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Old 11-27-2010, 06:58 AM   #60
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mistergreen is a secret agent from north korea :P
^^refering to post 45
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