Portable Luxmeter
Intro: Portable Luxmeter
This project is about making portable luxmeter. It can be used in schools, where children can measure different kinds of light sources.
Functions:
1. measure intensity of light in lux.
2. calculate solar irradiation from lux to watts/m2 (factor 112)
3. charging battery using USB port
Total cost is around 13 $ without case. Luxmeter take 15 mA, so it will works long time on one Li-Ion battery.
STEP 1: BOM
- For project you need this components(affiliate links, if you want to support me):
Arduino Pro Mini 5V
MAX44009
- Wide 0.045 Lux to 188,000 Lux Range
VCC = 1.7V to 3.6V () - ICC = 0.65µA Operating Current
- -40°C to +85°C Temperature Range
- Link
OLED display
Diagonal Screen Size:0.96"
Number of Pixels:128 x 64
Color Depth:Monochrome (Yellow&Blue)
Dimension:27.8 x27.3x 4.3 mm
Working Voltage: 3.3~ 5V DC
Power: 0.06W
MaxViewing Angle: >160 Degree
Duty:1/32Brightness ( cd/m2):150 (Typ) @ 5V
Interface: I2C
TP4056
- need USB to micro USB cable for charging
- input 5V
Li-Ion battery
- 3 - 4.2 Volts
- Link
18650 holder
Switch jumper
Cables and header
- female to female
- female and male header
- Link to cables
- Link to pin headers
STEP 2: Circuit
You need of course 5V Arduino to power it with Li-Ion battery (4,2 V!)
Connections:
Arduino - MAX44009 (same for OLED display)
A4 - SDA
A5 - SCL
VCC - VIN
GND - GND
TP4056 - Arduino Pro Mini
OUT+ - VCC
Arduino - battery
VCC - plus terminal (max 5 V for Arduino 5V)
Arduino - switch jumper
GND - first switcher
TP4056 - switch jumper
OUT - - second switcher
Battery - switch jumper
minus terminal - first and second switcher
STEP 3: Code
#include <Wire.h> #include <Adafrfuit_SSD1306.h>
#include <Adafruit_GFX.h>#include <Fonts/FreeSerif9pt7b.h>
#include "MAX44009.h"
MAX44009 Lux(0x4A);
float lux; float watts; // OLED display TWI address #define OLED_ADDR 0x3C Adafruit_SSD1306 display(-1); // restart display with reset button on arduino void setup() { Lux.Begin(0, 188000); display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR); display.clearDisplay(); display.display(); // display a line of text display.setTextSize(1); display.setTextColor(WHITE); display.setFont(&FreeSerif9pt7b); display.setCursor(1,15); display.print("MAX44009"); display.display(); } void loop() { lux=Lux.GetLux(); // get luxs watts =Lux.GetWpm(); // get watts/m2, only for SUN source display.fillRect(1, 20, 100, 100, BLACK); // create black rectangle on values position display.setCursor(1,40); display.print(lux); display.setCursor(80,40); display.print("lux"); display.setCursor(1,60); display.print(watts); display.setCursor(80,60); display.print("W/m"); display.setCursor(115,55); display.print("2"); display.display(); delay(1000); }
STEP 4: Solder
I create on prototype board socket for Arduino Pro Mini and pins for connect other things. I also build simple case from plywood. Use Plastic Zip Cable Wire for mounting display to door, also for joints.
STEP 5: Charging
I mount charging module - TP4056 to luxmeter. Red light showing charging, blue light not connected usb cable (micro usb). With switch jumper, I can switch on/off charging.
STEP 6: Formal Lesson Plan
1. Teacher describe what are luxs, watts and describe how to work with luxmeter.
2. Students will have task, to measure luxs:
a, choose light sources, and measure distance from source using length gauge
b, measure intensity of light source
c, write all values to table.
STEP 7: Own Measurement
- Street lamp gives 5 - 25 lux, probably depend on height of light source.
- Daylight gives 80 000 - 100 000 lux, depend on angle between sensor and sun beams.
- Sun under cloud during sunny day 15 000 lux
- LCD monitor give me 78 lux (0 cm distance), 63 lux (10 cm), 50 lux (20cm)
- smartphone 60 lux (0 cm)
- inside room during sunny day retracted blinds 60 lux
For calculation Watts/m2, you need to know luminous efficacy (in lumens per watt ).
For Sun it is around 110 lumens/W (on horizontal plane), 96 lumens/W ( on direct Sun beams).
So for Sun I get direct 700 - 900 W/m2 intensity.
Lux to watt/m2 calculator https://www.rapidtables.com/calc/light/lux-to-watt-calculator.html
5 Comments
MariuszW2 3 years ago
RobertoS147 4 years ago
Este equipo mide intensidad y radiación.
En las clases de laboratorio con los estudiantes necesitamos medir además la longitud de onda.
Cómo incorporar la medición de la longitud de onda a este dispositivo?
Michal Choma 4 years ago
This equipment measures intensity and radiation.
In laboratory classes with students we need to measure the wavelength.
How to incorporate the wavelength measurement to this device?
Then answer is: It is very hard to measure wavelength of light source. You mean measure spectrum of light? Like sun, or LED? I can only measure IR, FULL spectrum, in relative units. I think, the good project will be, add UV, IR and VISIBLE light detectors. It should works. Also I find sensor, which can measure what wavelengths can object absorb. https://learn.sparkfun.com/tutorials/spectral-triad-as7265x-hookup-guide/all?fbclid=IwAR3OEzOqO4sdi3-5gBWBg4oV7H761-nKQLnkcEq9njSDPbKJA5uswfLhmeM#hardware-overview
Lacybad 4 years ago
Michal Choma 4 years ago