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Old 10-07-2012, 08:01 PM   #136
Hoppy
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The rotary tool worked pretty well for roughly cutting away the unwanted parts. Then some filing and sandpaper finished it off. So far, so good!
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Old 10-07-2012, 09:00 PM   #137
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Default new tool so cool

i love it when a plan comes together and the ability to accquire a new tool i mean tools are cool! and if you can justify them that is even cooler. i like the idea of keeping most of the sensor body and just adding the tube w/acrylic bottom to make it water tight/ i have been thinking of a way to use it in a tank w/water by adding a aluminum arrow blank that you can get at the wally world and attaching it so you can hold it at the level you need for a reading. or even a telescoping antenna thing you can get at the shack. now i have to think of a way of a good attachment method. i have been experimenting like i told you with the hamburg filter thing and found that besides weldon gorilla CA glue will work also the other types would not. i have almost decided on the design as the one i used in he ten gallon QT tank will work but not very pretty. i have better plans for the 75 gallon one. "keep er up and get er done" hoppy!
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Old 10-07-2012, 09:18 PM   #138
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Default new tool so cool

i love it when a plan comes together and the ability to accquire a new tool i mean tools are cool! and if you can justify them that is even cooler. i like the idea of keeping most of the sensor body and just adding the tube w/acrylic bottom to make it water tight/ i have been thinking of a way to use it in a tank w/water by adding a aluminum arrow blank that you can get at the wally world and attaching it so you can hold it at the level you need for a reading. or even a telescoping antenna thing you can get at the shack. now i have to think of a way of a good attachment method. i have been experimenting like i told you with the hamburg filter thing and found that besides weldon gorilla CA glue will work also the other types would not. i have almost decided on the design as the one i used in he ten gallon QT tank will work but not very pretty. i have better plans for the 75 gallon one. "keep er up and get er done" hoppy!
doc
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Old 10-07-2012, 10:07 PM   #139
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Until I get the acrylic tube I have gone as far as I can. I just cut off the wires to the photodiode and soldered a new cable on. This was to avoid having to do any soldering near the plastic parts. A milivoltmeter indicates that the diode works fine now - about 250 mV in my room light. The tubing should arrive Tuesday or Wednesday.

The way I hold a PAR meter in the water is with an acrylic tube, which fits snugly into a next size larger piece of tube cemented to a strip of acrylic sheet which is the bottom of the sensor and arm to get the sensor away from the influence of the tube acting as the "probe". This is how I have our local aquarium club Quantum meter set up.
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Old 10-08-2012, 06:14 AM   #140
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that answered the question very well thank you
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Old 10-10-2012, 02:03 AM   #141
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Today my one foot length of 1 1/2 inch dia acrylic tube arrived, and with some difficulty I cut off a piece for the housing. First I found that the vendor had not cut the tube square on both ends, so I marked off a 21/32" length and used a small plastic miter box from HD and a hack sawa to cut it off. My cut was 1/32 out of square. So, I cut about a sixteenth of an inch off taking care to keep it square, then hand sanded it so it was square. I then clamped a "stop" to the miter box 11/16 inch from the blade, and cut that while slowly rotating the tube with the end hard against the stop. That worked very well, so after sanding to clean it up, I have my housing.

Next problem: the tube is 1 1/4" ID and the cylinder from the lux meter is also 1 1/4 " OD, so it won't fit inside the tube. Tomorrow I will sand either the inside of the tube or the outside of the cylinder until they fit together. (Probably inside the tube so I don't have to handle that lux meter cylinder any more than necessary.) As with any DIY project, each step hands you another little problem.
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Old 10-10-2012, 08:08 PM   #142
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After just a little sanding on both the OD of the lux meter cylinder and the ID of the acrylic cylinder:


Next, mark the acrylic cylinder for the wiring hole and drill it. Then put it together:


The hardest part was getting the tiny screw that holds the diode plate in place without hitting the electric cable behind it. I used needlenose pliers to put a kink in the cable to clear the mounting screw.

Finally, I got the lid back on top of the lux meter cylinder:


Somewhere along the way I put a hairline crack in the filter that fits in the lid, above the diode. I'm assuming that will have negligible effect on the operation.

To hold the lux meter cylinder in place, 4 small drops of Weldon #16.
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Old 10-10-2012, 08:53 PM   #143
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Shown with the filter pack of 4 filters attached with small strips of Scotch tape. The tape is primarily to keep them in place while the cosine diffuser is being glued on.



With the cosine diffuser glued on and the glue drying. I used Weldon #16, of course. When it dries well, I will put a filet of glue around the diffuser to cylinder joint on the outside. Before gluing this I tested it - it reads the same as it did when the original sensor was together, with the same filters.
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Old 10-10-2012, 10:22 PM   #144
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All that's left is to glue the sensor to the "handle", a 1 5/8" x 5" piece of acrylic, that seals the bottom of the sensor and lets me hold it in place under water without my arm or hand interfering with the measurement.

I think this is the ultimate PAR meter for the DIYer. Easy to make and cheap.
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Old 10-10-2012, 11:35 PM   #145
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very nice Hoppy!
i'm going have to order some acrylic tube and give this a try haha.
I noticed you now use 4 filters. Using the 6 you sent me orginally does the same thing correct?
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Old 10-11-2012, 01:14 AM   #146
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Quote:
Originally Posted by h4n View Post
very nice Hoppy!
i'm going have to order some acrylic tube and give this a try haha.
I noticed you now use 4 filters. Using the 6 you sent me orginally does the same thing correct?
No, with the 4 filters, the meter reads 10X PAR, so the 20,000 scale on the meter reads actual PAR. What I sent you made the meter read PAR, but not as accurately as with the 4 filters.

Look for a Rosco dealer near you and pick up a free sample stack from them, then you have enough of each of those 4 filters to make at least 4 meters. You could make a lot more, but then you have to worry about centering the filter stack over the window for the photodiode. With the 3/4 inch squares I used, the filters can't slide off far enough to be a problem.
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Old 10-11-2012, 04:13 AM   #147
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Great job on the new design, Have you tested in your tank how does it compare from the old test? Also what 4 filters are you using should i remove the other 2 filters you sent or just keep with the 6?
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Old 10-11-2012, 04:40 AM   #148
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Looks really good Hoppy! Appreciate the detailed instructions and especially the photos. When I get some time I'm going to try to make one.

But which 4 Rosco filters are you using? I thought you mentioned it before but can't seem to find it now.

I may ?? be going to Smoky Mountain Park next week so while down that way might try to find the Rosco dealer in Knoxville and pick up a sample stack.
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Old 10-11-2012, 11:11 AM   #149
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I see! So should I remove two filters then? Or just leave the 6?
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Old 10-11-2012, 04:01 PM   #150
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The four filters used are Rosco #398, #4830, #53, #302.


This is a different group from those I mailed out to a few people. Selecting the right filters is sheer drudgery, but drudgery like working a good jigsaw puzzle is. You have to get filters whose total transmissivity is 1/7.6 (.1316), and whose spectral transmissivities add up to give you a good final spectral sensitivity. This required a spreadsheet where I copied the spectral sensitivities of many of the Rosco filters and combined different groups until I found a good grouping. There is a lot of logic involved in doing that, but there are also several different ways to approach it, only one of which finally worked for me.

I think I have enough of the four I selected left for perhaps 3 more meters, if anyone wants them.

I know this has been a confusing thread, since this final effort is at least the 4th version, and all are different in significant ways. It was a learn as you go experience for me. If it helps in figuring this out, this final version starts at http://www.plantedtank.net/forums/sh...&postcount=132
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