Digital Light Intensity Meter Project Content: Introduction Block diagram Main components Schematic Diagram How do these components work together Practical Applications of light intensity meter Test result More info email Us : Engineeringgaragevir@gmail.com Regards xubair khan

1. “Digital Light Intensity Meter
Zubair khan 19092

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

3. Introduction :
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.
Description:
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

5. Main component:
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ADC Analog to digital convertor
Digital Encoder
Op Amp Comparator
LDR Light dependent Resistor
Digital Decoder
Display Driver
Display

6. Schematic diagram:

7. LDR Light dependent resistor :

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

9. 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

10. 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

11. 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).
• LT stands for Lamp Test
• BI stands for Blanking Input
• RBI stands for Ripple Blanking Input
BI/RBO
BCD
inputs
Outputs
to seven
segment
device
LT
RBI

12. 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

13. BCD to 7-Segment Display :

14. Application :
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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
Power requirements
Intensity range
Display type
Operating Temperature
Device type
Sample rate
Accuracy
Description
dc 5v (800 mA)
0~2000 Lux
7 segment led display 2 “ inch
30℃ ~ 65℃
solid-state control device
1 time/sec
±(3% +30d)

15. Test Result :

16. Test Result :

17. Hardware Testing & PCB Fabrication!!!!

24. Thank You!!
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