DIY PAR meter, Yeah you heard me

[O2surplus]

Originally Posted by mistergreen

lol, it's actually pretty easy now. It should go pretty fast. By the way, the meter you build is quality stuff.

Hey thanks! I just keep practicing. Design....build.....re-design.....re-build. I find my mistakes at each design iteration and keep going. Eventually I'm able to create something that actually works.LOL... I really want/need to learn how to write software though, but that may never happen, as this "Old dog" is finding it harder to learn "new tricks".

[Wolf19]

Originally Posted by mistergreen

Whenever I'm free. I still have ~14 more to build. After that, that's it for me.

Start turning a small profit on it I'm sure these would comfortably still sell at $80. Just personal opinion tho hah

[mistergreen]

Originally Posted by Wolf19

Start turning a small profit on it I'm sure these would comfortably still sell at $80. Just personal opinion tho hah

Nah, profit was never the goal. If you add shipping it's up around $80. Oh, I just saw the paypal fee. It's pretty high.

[tippeecanoe]

Very neat project. Thanks for sharing. I began reading this thread a little over a year ago when you first started this project and promptly lost track. After catching up, things have really progressed nicely! I may have to run down to the local RShack to see if I can pick up one of these Arduino things, an LCD display, etc., and build one of your PAR meters myself now! It doesn't seem terribly difficult, but at least I can always come here if I have any questions, I hope. Thanks again for all your hard work, both of you, and for sharing.

[NutZilla]

missed the sales, sigh......

[bhazard451]

Originally Posted by NutZilla

missed the sales, sigh......

same here. bummed

[Whitebeam]

How much tweaking of the calibration pot are you guys having to do to get the thing calibrated against the real PAR meter? Is the circuit still as the first post, but with a pot inline with the fixed resistor? If so, what's the typical pot setting when in cal?

Peter

[mistergreen]

Originally Posted by Whitebeam

How much tweaking of the calibration pot are you guys having to do to get the thing calibrated against the real PAR meter? Is the circuit still as the first post, but with a pot inline with the fixed resistor? If so, what's the typical pot setting when in cal?

Peter

I just measured the resistance of a calibrated meter. I got 24.7 k ohm.

There's an inline 15k and the pot is 10 or 15k.

Sent from my iPad using Tapatalk HD

[Whitebeam]

Originally Posted by mistergreen

I just measured the resistance of a calibrated meter. I got 24.7 k ohm.

There's an inline 15k and the pot is 10 or 15k.

My thanks for that. Any idea how consistent that 24.7 from one meter to the next?

Peter

[mistergreen]

not sure. I'll measure more when I make them but they all should be around that.

[tmclane]

Mistergreen,

I was wanting to build myself one of these 'good enough par' meters.
But I am having a bit of trouble imagining how you incorporated the diffuser plastic (2447) into the build. Would building an acrylic box out of it and mounting the diode inside be a good plan?

Any chance you can do a writeup of the final build howto including the plastic diffuser?

[mistergreen]

You just need the light to be filtered. It's up to you how you waterproof it. The black thing is a 1/4" Heyco cord grip. It makes the wire coming into the cup waterproof.

[tmclane]

Thanks for the pictures!

[genocdex]

mistergreen,
this is a very interesting read, for that i thank you very much. i have to admit i got about half way threw this thread before posting this but, did you ever find a way to callibrate these without going out and buying/barrowing an off the shelf unit?
i think id hate myself to buy something like this when i enjoy building it myself XD. at this point i just need a way to calibrate anything i come up with....

edit:
i saw you offered to calibrate another member's par meter, is that an open offer? when i build mine would you be willing to do the same for me?

again thanks so much for the great article!!!

[All your base]

Skimmed the thread and I have a few questions. Some you guys are probably sick of answering but I guess I missed em so forgive me.

The parts list in the first post claims to be updated 9-25-12, is that the most current information? I see a 27k resistor on the low side of the jack, I'm assuming that's the resistance that's being discussed recently as far as calibration (someone mentioned a 15k resistor and 15k pot, I think?)

What light source are you all calibrating to?

Are you all just using a pair of wires for the cable to the sensor? Has anyone had interference or noise issues and switched to shielded cable?

Ironic that you're using 2447 as the diffuser. That's what my overflow box and ATS scaffolds and a bunch of other nicknacks on my tanks are built from, and I have lots of it around the shop.