A light meter is a device used to measure the amount of light in digits.
This device will also help us in Energy Audit, controlling light intensity in polyhouse

The device made by me is very simple D-I-Y lux meter. Its low cost & open source device

I used microcontroller ADC(Analog to Digital convertor)
which sense light through LDR in analog and shows output on digital display.

2)Who's done what beforehand?

Lux meter is available commercially in the market. Though its not commonly available in schools or with technician carrying out rural lighting projects.

Many times people specify their lighting requirement in terms of wattage consumed. Incandescent lamp consumes more power than CFL or LED lights.
But light intensity delivered per wattage of power is different in both cases. I have not found simple D-I-Y kit for Lux meter.

In camera, there are good sensors to control flash light by measuring light intensity. But there are many other applications like house lighting, classroom lighting, polyhouse lighting. They need device to measure light and take decision. I want to work in that area.

I did this device in FABLAB with local available material,less complicated and can be used as DIY kit

3)What did you design

I have designed D-I-Y Kit for lux meter from locally available component. Following are its main parts :

a) Electronic Design

1)Design Input circuit with Light sensor

2)Output circuit with LCD screen

For LUX meter I have design my board as per following.,

Resistor,microcontroller (Attiny44-for programming and ADC),
photovoltaic sensor(important because this sense light intensity and convert analog signal to digital)and LCD screen display

we will get output in digitsal format (Lumens.Micro-controller implementation of ADC and other calculations and interface with LCD).

b) Assembly part

1)2D design for laser cutter assembly

2)3D design for holder assembly plus I design and print trophy

4)What material and components were used?

List of components:

(1)resistors
10k-3nos.

470 ohm - 2nos.

LDR - 1no.

Switch - 2nos.

Capacitors 0.1uf - 2nos.

Connectors - 3 PIN -5nos.

LCD JHD162a - 1NO.

LED - 1/2 watt - 1no.

Wires, soldering material, SMD soldering gun, twizzer, cutter, wire striper etc.

5)Whcih Machine and software tool?

Software tools

1)Eagle - Schematic design for electronics production

2)Inkscape,Auto cad,Libre cad - 2Assembly design

3)Tinker cad, Blender, Google sketch up - 3D design

4)TUX paint - Editing of files

5)V-curve pro-Shopbot design and toolpaths

Machine

1)Modela MDX20-Milling PCB,Engraving machine wax,Scaning

2)Vinyl cutter-Cutting Radium paper, mill PCB circuit

3)3D printer-Print job in 3D

4)Laser Cutter-Cut assembly on acrylic

Some hand tools for finishing purpose

6)Where did they come from?

I am very clear about my project so I have decided to make LUX meter Open source device with localy available material
my FABLAB is situated in rural area already I reached upto my goal and used all machine available in Vigyan Ashram acept Shopbot
I went in COEP,Pune FABLAB and complete my remaining task there,On other hand I used electronic componenets from FABLAB inventory and some remaining from market

7)How much did they cost?

Total cost of my project is less than Rs.1000/- ( $ 15 ) only. I have added 12% labour charges.I have used following SMD components for my projects, details as per below,

Resistor - 50paise (each)

Capacitors - 25paise (each)

LED(0.5 watt) - 50 paise

LDR (NOT SMD) - Rs.2/-

Attiny 44 - Rs.60/-

switch - Rs.1/-(each)

LCD display (JHD162A)-Rs.300/-

connectors strip - Rs.10

PCB board (size 5"x4")- Rs.60

Soldering metal (50 meter) - Rs.50

Laser cut container (3mm thk) - Rs.400

TOTAL = Rs.1000/-($13-$15)

8)What parts and systems were made?

Parts

PCB design mill on Modella MDX20 machine

FAB ISP for burning code or if you don't have then you can useSerial or parallel port for burning of code,

LCD screen (Purchase from market)

9)What processed were used?

1)Designing

2)PCB milling, wax engraving

3)Code writing and program burning

4)3D printing

5)Laser cutting

10)What question were answered?

I want to make this gadget for school children to teach them about light intensity. This D-I-Y kit will also be a good exercise for practicing soldering / programming / sensors and casing design.

I have made circuit less complex. I have also used simple LDR as sensor It is very cheap and locally available.

The program written for the circuit is very simple. Its only of few lines and can easily explain to children.

I have calibrated it with commercially available LUX meter and found it to be sufficiently accurate.

I have also worked on making D-I-Y instructions so that it can be integrated in our school assignments.

11)How was it evaluated?

I have calibrated my device with standard lux meter. IT was calibrated at complete darkness, with 1W LED light and 200 w light bulb intensity.

This device is calibrated for reading of lumense on lux meter,its accuracy and callibaration.

12)What are the implication?

After making this device I have calibrated with standard lux meter and I found that I reached almost accurate range.