“Digital Light Intensity Meter

Zubair khan 19092

• Introduction • Block diagram• Main components • Schematic Diagram• How do these components work together• Practical Applications of light intensity meter • Test result

Content:

Here is lux meter or light intensity meter circuit that has many applications in real world but the main application of this meter is use for measuring light intensity

This project aims to design and develop an inexpensive and accurate light intensity meter basically using only electronics components. It also provides an opportunity to apply the knowledge of electronics module to design a prototype of a product.

Introduction :

Description:

• ADC Analog to digital convertor• Digital Encoder• Op Amp Comparator• LDR Light dependent Resistor • Digital Decoder• Display Driver• Display

Main component:

Schematic diagram:

LDR Light dependent resistor :

Voltage Divider Network :Connecting a light dependent resistor in series with a standard resistor like this across asingle DC supply voltage has one major advantage a different voltage will appear at theirjunction for different levels of light.

Analog-to-Digital (A/D) Conversion:

The simultaneous, or flash, method of A/D conversion uses parallel comparators to compare the linear input signal with various reference voltages developed by a voltage divider. When the input voltage exceeds the reference voltage for a given comparator, a high level is Produced on that comparator’s output

8 - to - 4 bit Encoder or [Priority Encoder] :The Priority Encoder solves the problems mentioned above by allocating a priority level to each input. The priority encoders output corresponds to the currently active input which has the highest priority. So when an input with a higher priority is present, all other inputs with a lower priority will be ignored. The priority encoder comes in many different forms with an example of an 8-input priority encoder along with its truth table shown below

BCD to 7-Segment Display Decoder :

Another useful decoder is the 74LS47. This is a BCD-to-seven segment display with active LOW outputs

The a-g outputs are designed for much higher current than most devices (hence the word driver in the name).

BCD inputs

LT

RBI

BI/RBO

Outputs to seven segment device

• LT stands for Lamp Test• BI stands for Blanking Input• RBI stands for Ripple Blanking Input

7-Segment Display:

The Common Cathode Display (CCD) – In the common cathode display, all the cathode connections of the LED's are joined together to logic "0" or ground. The individual segments are illuminated by application of a "HIGH", logic "1" signal to the individual Anode terminals

The Common Anode Display (CAD) – In the common anode display, all the anode connections of the LED's are joined together to logic "1" and the individual segments are illuminated by connecting the individual Cathode terminals to a "LOW", logic "0" signal

BCD to 7-Segment Display :

Application : • Sensitive Medical Equipment• Checking lamp or fluorescent tube light illumination• Automatic solar tracking device• Measurement Sunlight lux in day time• light sampling• Checking light intensity in the room.• Automatic street lights intensity controlled.

Devices Specifications

Function Description Power requirements dc 5v (800 mA)

Intensity range 0~2000 Lux Display type 7 segment led display 2 “ inch

Operating Temperature 30℃ ~ 65℃ Device type solid-state control device Sample rate 1 time/sec

Accuracy ±(3% +30d)

Test Result :

Test Result :

Hardware Testing & PCB Fabrication!!!!

Thank You!!

Join us on Facebook : Engineering garage v=ir