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Old 09/02/2016, 07:20 AM   #76
ksc
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That's quite a correction needed on the mq-500.


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Old 09/02/2016, 11:25 AM   #77
theatrus
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Quote:
Originally Posted by shermanang View Post
Hi Theatrus,

How can i get myself one of these?

On the multi meter it show the PAR reading direct?
Can I hook my old Apogee sensor? Or I need to get the new sensor?


It's not needed with the old sensor head - almost any multimeter can read those directly (just multiply by 5)


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Old 09/02/2016, 01:04 PM   #78
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Originally Posted by Mark426 View Post
For those that are interested in real life comparisons between the old and new Apogee sensor go over to reef builders. They have a nice write up. If you cant find it there search for "Immersion Effect" on their website.
Interesting - based on this I don't really see any reason to upgrade to the new sensor...


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Old 09/02/2016, 01:52 PM   #79
theatrus
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Originally Posted by koral_lover View Post
Interesting - based on this I don't really see any reason to upgrade to the new sensor...


The spectral response is much better, even if the incident light angles are far worse. The latter is easier to correct for since it's only dependent on indices of refraction


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Old 09/02/2016, 02:34 PM   #80
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Originally Posted by theatrus View Post
The spectral response is much better, even if the incident light angles are far worse. The latter is easier to correct for since it's only dependent on indices of refraction

Quote:
Apogee took these underwater immersion factors in mind and has come up with a correction factor which seems to rectify our expected PAR values quite a bit.

When measuring PAR with the old MQ-200 or similar sensors, a correction factor of 1.07 should be added to all light readings.
Meanwhile if you have the new Apogee MQ-500, the correction factor is much higher at 1.32, basically increasing the underwater light measurements by 32%.
but again, it "captures" more of the bandwidth more accurately.. so the conversion factor is more global than w/ the 200 which still has the same old spectral "errors"..

They should try a teflon diffuser lens..
http://engineering.case.edu/centers/...phous_fluo.pdf

not going to pretend to actually understand the ramifications of the above.. Just a gut feeling..

Quote:
Teflon ŽAF polymers have the lowest index of refraction of any known polymer, making them very suitable as low-index claddings for
waveguide applications. Because of the combination of electric and optical properties, the use of Teflon ŽAF fluoropolymers is very attractive in photonics and photovoltaics.
AND I'm guessing they are not using a Teflon polymer lens now.



Last edited by oreo57; 09/02/2016 at 02:49 PM.
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Old 11/21/2016, 01:32 PM   #81
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Interesting I was just googling these meters as I noticed some decent Black Friday Sales. Come across this thread with someone posting about an article on ************. Go over there, and not 3 hours ago, another revision for a nwe meter.

https://************.com/2016/11/21/...ter-par-meter/


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Old 12/05/2016, 05:07 PM   #82
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It's blocked. Easiest to share what to google to get to it.


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Old 12/06/2016, 06:55 PM   #83
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Originally Posted by nighthawk26 View Post
Interesting I was just googling these meters as I noticed some decent Black Friday Sales. Come across this thread with someone posting about an article on ************. Go over there, and not 3 hours ago, another revision for a nwe meter.

https://************.com/2016/11/21/...ter-par-meter/
It's not a new sensor but a new reader. The sensor is the same. If you are not going to buy the reader as well then it's the same. Blueacro's PCB adapter will be the same.


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Old 06/16/2021, 02:05 AM   #84
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I have the SQ-500 sensor and was researching op-amps with low DC offset error to build my own amplifier circuit and stumbled across this thread. I may just purchase this one since you did all the legwork. I saw in the schematics there is a filter circuit in the op-amp circuit. What's the cutoff frequency? I'm only curious because I'm unsure how the sensor responds to PWM dimmed LED lighting. The spec sheet indicates the SQ-500 has a response time of <1ms, so it could in theory be used to read PWM signals less than 1khz. Is this sort of averaged out in the analog circuitry, or does this need to be accounted for in the microcontroller code? Will PWM dimming create any sort of aliasing problems in the sampling, or do the filters take care of that?


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Old 07/08/2021, 09:13 AM   #85
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Quote:
Originally Posted by ClownWrangler View Post
I have the SQ-500 sensor and was researching op-amps with low DC offset error to build my own amplifier circuit and stumbled across this thread. I may just purchase this one since you did all the legwork. I saw in the schematics there is a filter circuit in the op-amp circuit. What's the cutoff frequency? I'm only curious because I'm unsure how the sensor responds to PWM dimmed LED lighting. The spec sheet indicates the SQ-500 has a response time of <1ms, so it could in theory be used to read PWM signals less than 1khz. Is this sort of averaged out in the analog circuitry, or does this need to be accounted for in the microcontroller code? Will PWM dimming create any sort of aliasing problems in the sampling, or do the filters take care of that?
They have also now added the ePAR sensor which is even better:

https://www.apogeeinstruments.com/epar-sensors/


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