DIY PAR meter, Yeah you heard me

[mistergreen]

Originally Posted by HD Blazingwolf

I still need to get my meter calibrated.... anyone up for grabs????!!!! i know someone has a PAR meter, hoppy. green!!!

I have one but how do you even calibrate your lux meter?

[HD Blazingwolf]

Measure it against known par values and divid to get correct par. I believe it to be at 61 lux/par. Going against manufacturer numbers. Id measured against my light and hoppy's chart it seems pretty accurate as well

[mistergreen]

ah, you're doing with mathematically. I can't send you my PAR sensor (you need a volt meter) but if you want to send me you lux meter, let me know.

[HD Blazingwolf]

I have a volt meter but i understand. Me shipping a 20 dollar meter and potentially not getting it back is much better than u losing a par meter

Shoot me an address

[Hoppy]

The ratio between PAR and Lux readings, for 6500-10000K fluorescent lights is more like 76 than 60. But, if you are measuring the light from a pink bulb, the sun, incandescent bulbs, etc. the ratio can be much different. Lux meters are very useful for rough measurements to see if a light fixture/bulb is going to work well for you, but they are not useful for actual research type measurements - determining how effective an actinic bulb is compared to a 6700K bulb, for example.

[HD Blazingwolf]

Well i have a 6 k, 6500k a purple bulb and a red one.. does that help LOL!

[mcarroll]

Originally Posted by Hoppy

Lux meters are very useful for rough measurements to see if a light fixture/bulb is going to work well for you, but they are not useful for actual research type measurements - determining how effective an actinic bulb is compared to a 6700K bulb, for example.

Unbelievably well said! There's a lot of truth in that statement and I think it bears repeating. :-)

(Yes, I meant it....everyone read that again! )

Having a $20 LUX meter to go by is so eye opening (no pun) - so much better at showing you what the light really does as it radiates from your light source, as it overlaps with other light sources, etc, than "eyeballing it". If you're someone who DIY's or experiments with your lighting at all in any way, it would seem a shame not to have one of these to use. Even without being calibrated to anything (which just makes a LUX so much more informative).

-Matt

[Whitebeam]

Any chance you could post the latest Arduino sketch for this please? I have the sensor and an Uno and would love to have a play.

Also, has anybody made a unit using the TCS3200D sensor that was suggested?

Peter

[O2surplus]

Here's the actual sketch that we used for the "Close Enough" PAR Meter.

// CLOSE ENOUGH PAR Written in Arduino 23 By MISTERGREEN

#include <LiquidCrystal.h> // modified by O2surplus to include correct LCD pinout for "CLOSE ENOUGH PAR Meter" V1.0
                           //  Code also includes provision for seial output of PAR values to a PC.
float average = 0;
float output = 0;
float factor = 1.52;
unsigned long time; 
int counter = 0;
// create the LCD
LiquidCrystal lcd(8, 7, 5, 4, 16, 2);
// set up backlight
int bkl = 6; // backlight pin

void setup() {
  time = millis();
  // set up the LCD's number of rows and columns: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("CLOSE ENOUGH PAR");
  pinMode(bkl, OUTPUT);
  digitalWrite(bkl, HIGH);
  // initialize the serial communication:
  Serial.begin(115200); // Max for Arduino Uno
}

void loop() {

  int sensorValue = analogRead(0);
  average += sensorValue;
  counter++;

  //every second or 1000 millis
  if(millis() > time+1000) {
    //corrections to fit par
    average = average/counter;

    if(average <= 560) {
      factor = 1.55;
    } 
    else {
      factor = 1.36;
    }
    //corrects for high PAR
    output = average * factor;

    // set the cursor to column 0, line 1
    // (note: line 1 is the second row, since counting begins with 0):
    lcd.setCursor(0, 1);
    // print the number of seconds since reset:
    lcd.print(output);
    // send PAR data to the Serial output.
    Serial.println(output, BYTE);
    
  }
  //reset timer & counter to get ready for the next second.
 // time = millis();
  counter = 0;
  average = 0;
 delay(1000);
}

[Whitebeam]

Superb - my thanks.

I just want to take relative readings between my current T5s and my new multi-chip leds, once I've assembled them, so I won't need to worry too much about calibration.

Peter

[bhazard451]

Originally Posted by mistergreen

I should have a batch of 5 or six done at the end of this month.

I got tired of getting allergies and tearing out carpeting at the moment so I'm preoccupied.

I absolutely must have one of these when they are ready. I rarely use my Apogee now, but a need for it always randomly pops up. This would help me tremendously.

[mistergreen]

Originally Posted by bhazard451

I absolutely must have one of these when they are ready. I rarely use my Apogee now, but a need for it always randomly pops up. This would help me tremendously.

huh?? If you have an Apogee, why would you need this?

[bertyboy69]

Originally Posted by mistergreen

I should have a batch of 5 or six done at the end of this month.

I got tired of getting allergies and tearing out carpeting at the moment so I'm preoccupied.

just wondering if you finished these up yet. im very intrested in one i was going to build one myself but the semester is starting up on monday and ill be way to busy.

just wondering if i missed these units or if they arent ready yet.

[bhazard451]

Originally Posted by mistergreen

huh?? If you have an Apogee, why would you need this?

I don't need $350 of apogee hanging around for the few times I use it, when this can do the job for much less.

[dzaninov]

Construction and testing of an inexpensive PAR sensor:
http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf