Published May 26, 2020 © GPL3+

Light Control with Automated Control Systems

We will see how easily can control a parameter (light, sound) using Operation Amplifiers. It is an introductional example to PID controller.

IntermediateFull instructions provided10 hours2,142

Light Control with Automated Control Systems

Things used in this project

Hardware components

Arduino UNO

9V 1A Switching Wall Power Supply

Photodiode, 12 °

High Brightness LED, White

Jumper wires (generic)

Trimmer Potentiometer, w/ Knob

Texas Instruments General Purpose Dual Op-Amp

Resistor 10k ohm

Resistor 1k ohm

Through Hole Resistor, 274 ohm

TaydaElectronics DC POWER JACK 2.1MM BARREL-TYPE PCB MOUNT

Breadboard (generic)

Software apps and online services

Arduino IDE

Hand tools and fabrication machines

Tape, Barricade

Story

Introduction

We are going to control the brightness of a LED automatically. But we need to know some basics about our friends..... OpAmps. Therefore, I will give you a hint.

Operational amplifiers

are linear devices that have all the properties required for nearly ideal DC amplification and are therefore used extensively in signal conditioning, filtering or to perform mathematical operations such as add, subtract, integration and differentiation.

An Operational Amplifier is basically a three-terminal device which consists of two high impedance inputs. One of the inputs is called the Inverting Input, marked with a negative or “minus” sign, ( – ). The other input is called the Non-inverting Input, marked with a positive or “plus” sign ( + ).The difference of two inputs will be enhainced by a gain.

Below we can see a type of amplifier. But we have many different types of OpAmps based on our purposes.

Figure 1

Differental amplifier

amplifies the difference between two voltages making this type of operational amplifier circuit a Subtractor unlike a summing amplifier which adds or sums together the input voltages.Amplifier's gain depends on the price of resistor we use. So, we can control the value of volts we can amplify in output.

For more: https://www.electronics-tutorials.ws/opamp/opamp_5.html

Figure 2

Figure 3

Voltage Follower(Unity Gain Buffer)

If we made the feedback resistor, Rƒ equal to zero, (Rƒ = 0), and resistor R2 equal to infinity, (R2 = ∞), then the circuit would have a fixed gain of “1” as all the output voltage would be present on the inverting input terminal (negative feedback). This would then produce a special type of the non-inverting amplifier circuit called a Voltage Follower or also called a “unity gain buffer”.

Figure 4

Phototransistors

Elements that detect optics radiation and convert perspective electricity signal

Separated in :

Figure 5

"Window" at the top

• Often the Base, which is sensitive to light, does not

is connected (as in our circuit) and simply serves to generate electricity

in the transistor.

• In our circuit, its connection transistor is that of the common collector. THE

emitter is connected via one load on the ground and the collector on the voltage.

The exit is on the show.

• The circuit gives the output voltage that ranges from a low to a high price

is connected (as in our circuit)

http://m.eet.com/media/1049853/C0086-Table1a.gif

Figure 6

Interested Parameter

Spectrum Response
Lineality of signal output
Sensitivity
Response time to changes incident light

Automated System

Closed loop of photoresistor control system. But first, we need to know some important things about manifacturing process.

Figure 7 Closed-Loop Circuit

As an input we use a potentiometer which gives different voltage values. The output is a result of the light that the phototransistor will receive and will convert it into voltage. It depends on both the geometric characteristics of the LED-phototransistor pair and the environmental conditions.For example natural light that affects the layout. The differental amplifier plays the role of controller as it controls the voltage that will supply the LED. So it controls the operation of both the LED and the phototransistor. The voltage follower acts as the actuator as it will supply the LED through it.

LED is the process as we want to control its brightness. The phototransistor plays the role of the sensor as it "feels" any fluctuation of the voltage through the photons it receives. So through the feedback it sends a signal to the controller depending on the conditions.

Anything that would prevent the sensor from taking measurement. Any obstacle (eg paper). Noise can be of many kinds. From our experience we have seen noise in jumpers due to their function as antennas. But it may also be due to other electronic components.

Even in an unwanted voltage that may interfere.

IMPORTANT: Install the LED and the phototransistor in opposite, close positions on the actual breadboard!

Figure 8 Blueprint

It is needed for the operation of 9 V at 8 and grounding at 4

So, we can see the chart from arduino voltage meter. We use arduino to make sampling of voltage prices to time for the LED and phototransistor. Below can observe the efficiency of system in case of effecting by external enviroment.

You can easily converter your arduino to voltage meter through serial plot. But I cannot show how to do that immidiately. Althought, I will share the code. Many tutorials, many ways! Try them out and have fun!

Figure 9 LED

Figure 10 LED

Figure 11 Phototransistor

Code

CODE FOR VOLTAGE METER

int analogInput = 1;
float Vout = 0.00;
float Vin = 0.00;
float R1 = 100000.00; // resistance of R1 (100K) 
float R2 = 10000.00; // resistance of R2 (10K) 
int val = 0;
void setup(){
   pinMode(analogInput, INPUT); //assigning the input port
   Serial.begin(9600); //BaudRate
}
void loop(){
   
   val = analogRead(analogInput);//reads the analog input
   Vout = (val * 5.00) / 1024.00; // formula for calculating voltage out i.e. V+, here 5.00
   Vin = Vout / (R2/(R1+R2)); // formula for calculating voltage in i.e. GND
   if (Vin<0.09)//condition 
   {
     Vin=0.00;//statement to quash undesired reading !
  } 
Serial.print("\t Voltage of the given source = ");
Serial.print(Vin);
delay(1000); //for maintaining the speed of the output in serial moniter
}

Credits

Iasonas Christoulakis

9 projects • 31 followers

Biomedical Engineer MedispLab Instructor Former General Manager at IEEE NTUA Student Branch

Thanks to Michail Kalakos.

Light Control with Automated Control Systems

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Introduction

Operational amplifiers

Differental amplifier

Voltage Follower(Unity Gain Buffer)

Phototransistors

Interested Parameter

Automated System

Schematics

Schematic for light control

Video about function

Code

CODE FOR VOLTAGE METER

Credits

Iasonas Christoulakis

Comments

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Light Control with Automated Control Systems

Light Control with Automated Control Systems

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Introduction

Operational amplifiers

Differental amplifier

Voltage Follower(Unity Gain Buffer)

Phototransistors

Interested Parameter

Automated System

Schematics

Schematic for light control

Video about function

Code

CODE FOR VOLTAGE METER

Credits

Iasonas Christoulakis

Comments

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