Planted Tank Guru

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Truly some pioneering DIY action! Great job!
"The fewer our wants, the nearer we resemble the gods." — Socrates
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No more Bow ties
Thanks. Trying to make the hobby more accessible.
No more Bow ties
I don't think I showed you how I'm reading the values so far.
It's all through USB... It's supplying the ardiuno power and a way for the ardiuno to communicate to my computer...
This is my serial monitor outputting the values.
The values jump/dance around like it's being hit by photons, kinda cool. So I wrote the code to find the average within every second...
NONPAR code...(NOT FINAL)
Oh, I double checked the readings by going outside... Full sun will give me the maximum value of 1023.. In the shade, around 100120.
It's all through USB... It's supplying the ardiuno power and a way for the ardiuno to communicate to my computer...
This is my serial monitor outputting the values.
The values jump/dance around like it's being hit by photons, kinda cool. So I wrote the code to find the average within every second...
NONPAR code...(NOT FINAL)
Code:
unsigned long average = 0; unsigned long time; int counter = 0; void setup() { Serial.begin(9600); time = millis(); } void loop() { int sensorValue = analogRead(0); average += sensorValue; counter++; //every second or 1000 millis if(millis() > time+1000) { average = average/counter; Serial.println(average); //reset timer & counter to get ready for the next second. time = millis(); counter = 0; average = 0; } }
No more Bow ties
For those wanting to play with a microprocessor, check the Texas instrument one. It's only $4.50!!!
http://processors.wiki.ti.com/index....+launchpadwiki
I haven't played with it but my dad got one for me.
http://processors.wiki.ti.com/index....+launchpadwiki
I haven't played with it but my dad got one for me.
Planted Tank Guru
I think PAR in full sun at midday is around 2000. That suggests your readings may be about half of the true PAR values.
Hoppy
No more Bow ties
Yeah, I'm mapping out the values now to see the relationship...
Hoppy, I have a question about your PAR  distance chart.
Your graph implies a parabolic curve, meaning the closer you get to the bulb, the more it gets to infinity or to the max value (the sun 2000 PAR). This is assuming your bulb is outputting at the level of the sun? It doesn't seem right.
I'm definitely getting a fixed value no where near the maximum with my DIY meter.
Hoppy, I have a question about your PAR  distance chart.
Your graph implies a parabolic curve, meaning the closer you get to the bulb, the more it gets to infinity or to the max value (the sun 2000 PAR). This is assuming your bulb is outputting at the level of the sun? It doesn't seem right.
I'm definitely getting a fixed value no where near the maximum with my DIY meter.
Planted Tank Guru
Super awesome DIY. Keep your findings coming.
No more Bow ties
Here you go..
The proportions doesn't look like a x2 constant calibration... It looks like a gaussian curve (bell curve).... Will work on the equation unless some math wiz out there beat me to it
The proportions doesn't look like a x2 constant calibration... It looks like a gaussian curve (bell curve).... Will work on the equation unless some math wiz out there beat me to it
No more Bow ties
Ok,
I found the equation... There were some guessing going on because I didn't know what hoppy's chart start value is.
It looks like these bulbs output are bell curves rather than parabolas.
f(d) = A * (11e^(d^2/(2*35^2)))
A is the value from my DIY sensor, d is distance.
I'll graph this out to see how close they fit.
I found the equation... There were some guessing going on because I didn't know what hoppy's chart start value is.
It looks like these bulbs output are bell curves rather than parabolas.
f(d) = A * (11e^(d^2/(2*35^2)))
A is the value from my DIY sensor, d is distance.
I'll graph this out to see how close they fit.
Wannabe Guru
Great idea. This might be my next dig as well.
Sent from my DROIDX using Tapatalk
Sent from my DROIDX using Tapatalk
Patience is the name of the game.
Changing Mood. Rimless Array  DIY LED Light Panel  DIY Rimless tank + Stand  DIY 72L Stand
Changing Mood. Rimless Array  DIY LED Light Panel  DIY Rimless tank + Stand  DIY 72L Stand
Planted Tank Guru
The inverse square relationship of PAR and distance only works within a relatively small range of distances. When you get close to the bulb it breaks down. I determine relationships like this by just plotting the data on loglog graph paper. If the points form a straight line, it demonstrates that one variable is a function of a power of the other variable, with the slope of the straight line being the power.
It is very hard to measure distances very accurately with tests like this, and PAR meter readings can fluctuate as you read the meter, and vary from hour to hour. So each data point can be assumed to have a pretty large uncertainty. Considering all of that, if a line with a slope of minus 2 will fit the data points reasonably closely within the distance range that is relevant for aquariums, it is a good approximation to assume the inverse square relationship. Then, when you toss in values for multiple bulb fixtures, using the PAR number divided by number of bulbs, and those data points follow the same line, you can see that it is a good approximation to say that n bulbs give n times the PAR of one bulb.
It makes no difference to us, when we are looking for an aquarium light, whether or not the PAR varies with square of distance at distances of 1 inch to 4 inches, so I never bothered to measure it at those distances, except with single LEDs. Single LEDs are so near a point source that the inverse square relationship will hold true at even 34 inches from the single LED. It gets much more complicated when you have an array of LEDs.
It is very hard to measure distances very accurately with tests like this, and PAR meter readings can fluctuate as you read the meter, and vary from hour to hour. So each data point can be assumed to have a pretty large uncertainty. Considering all of that, if a line with a slope of minus 2 will fit the data points reasonably closely within the distance range that is relevant for aquariums, it is a good approximation to assume the inverse square relationship. Then, when you toss in values for multiple bulb fixtures, using the PAR number divided by number of bulbs, and those data points follow the same line, you can see that it is a good approximation to say that n bulbs give n times the PAR of one bulb.
It makes no difference to us, when we are looking for an aquarium light, whether or not the PAR varies with square of distance at distances of 1 inch to 4 inches, so I never bothered to measure it at those distances, except with single LEDs. Single LEDs are so near a point source that the inverse square relationship will hold true at even 34 inches from the single LED. It gets much more complicated when you have an array of LEDs.
Hoppy
No more Bow ties
Doh! there's no way to tell the sensor what the distance is to the light source... will have to rethink the equation.
No more Bow ties
Quote:
Originally Posted by Hoppy
View Post
The inverse square relationship of PAR and distance only works within a relatively small range of distances. When you get close to the bulb it breaks down. I determine relationships like this by just plotting the data on loglog graph paper. If the points form a straight line, it demonstrates that one variable is a function of a power of the other variable, with the slope of the straight line being the power.
It is very hard to measure distances very accurately with tests like this, and PAR meter readings can fluctuate as you read the meter, and vary from hour to hour. So each data point can be assumed to have a pretty large uncertainty. Considering all of that, if a line with a slope of minus 2 will fit the data points reasonably closely within the distance range that is relevant for aquariums, it is a good approximation to assume the inverse square relationship. Then, when you toss in values for multiple bulb fixtures, using the PAR number divided by number of bulbs, and those data points follow the same line, you can see that it is a good approximation to say that n bulbs give n times the PAR of one bulb.
It makes no difference to us, when we are looking for an aquarium light, whether or not the PAR varies with square of distance at distances of 1 inch to 4 inches, so I never bothered to measure it at those distances, except with single LEDs. Single LEDs are so near a point source that the inverse square relationship will hold true at even 34 inches from the single LED. It gets much more complicated when you have an array of LEDs.
It is very hard to measure distances very accurately with tests like this, and PAR meter readings can fluctuate as you read the meter, and vary from hour to hour. So each data point can be assumed to have a pretty large uncertainty. Considering all of that, if a line with a slope of minus 2 will fit the data points reasonably closely within the distance range that is relevant for aquariums, it is a good approximation to assume the inverse square relationship. Then, when you toss in values for multiple bulb fixtures, using the PAR number divided by number of bulbs, and those data points follow the same line, you can see that it is a good approximation to say that n bulbs give n times the PAR of one bulb.
It makes no difference to us, when we are looking for an aquarium light, whether or not the PAR varies with square of distance at distances of 1 inch to 4 inches, so I never bothered to measure it at those distances, except with single LEDs. Single LEDs are so near a point source that the inverse square relationship will hold true at even 34 inches from the single LED. It gets much more complicated when you have an array of LEDs.
Planted Tank Guru
I plotted your data for the 3 bulb unit on log log paper and got:
The line is the slope if the data follows the inverse square rule. You can see how much scatter there is, and that the close to the bulb readings diverge from the other data. This isn't much different from the data I got from other sources. And, it is why the charts I made are only good for approximating the PAR  you have to measure in your tank with your lights to get really accurate measurements.
If I were to add your data to my charts I would read off data points from that line, not your actual data. That reduces the scatter a great deal, and makes it possible to do this.
The line is the slope if the data follows the inverse square rule. You can see how much scatter there is, and that the close to the bulb readings diverge from the other data. This isn't much different from the data I got from other sources. And, it is why the charts I made are only good for approximating the PAR  you have to measure in your tank with your lights to get really accurate measurements.
If I were to add your data to my charts I would read off data points from that line, not your actual data. That reduces the scatter a great deal, and makes it possible to do this.
Hoppy
No more Bow ties
This is the best I can do, with my sensor
(multiply 8 to the single bulb data)
But as we know I went outside into the sun I'd get 8000 PAR
I'm curious to see if the mamamatsu photo diode would give me a better output. I think the Infra Red is affecting the readings.
(multiply 8 to the single bulb data)
But as we know I went outside into the sun I'd get 8000 PAR
I'm curious to see if the mamamatsu photo diode would give me a better output. I think the Infra Red is affecting the readings.

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