For the PAR inclined . Apogee upgraded sensor

[ksc]

That's quite a correction needed on the mq-500.

[theatrus]

Originally Posted by shermanang

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)

[koral_lover]

Originally Posted by Mark426

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...

[theatrus]

Originally Posted by koral_lover

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

[oreo57]

Originally Posted by theatrus

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

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..

Teflon ®AF 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 ®AF fluoropolymers is very attractive in photonics and photovoltaics.

AND I'm guessing they are not using a Teflon polymer lens now.

[nighthawk26]

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/

[karimwassef]

It's blocked. Easiest to share what to google to get to it.

[gus6464]

Originally Posted by nighthawk26

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.

[ClownWrangler]

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?

[shred5]

Originally Posted by ClownWrangler

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/