Line Follower Robot-Based LDR

Line follower robot circuit at its core is 2 pieces of current DC motors based on input from sensors LDR, if the white lines mendeksi LDR (light) and black lines (dark) then there will be a change in resistance value of LDR, which will activate / deactivate the transistor 2N3904 . To set the input voltage to the base in order to create a 2N3904 transistor saturation, the voltage divider is used, in this case trimpot / potentiometer 50k-100k. Changes 2N3904 transistor logic will also cause the LED on or off, as an indicator of whether LDR read black line / white. Changes in the collector logic 2N3904 well as input on the basis 2N2907, which will enable / disable the DC motor, which is a 2N2907 transistor switching transistor standard. Consider the following picture: 

 

You can use some of the items used to make these robots, for example using the wheel as the wheel BB Rexona robots. Components and the necessary equipment is complete: 

* 2 pieces LDR light sensor 

* IC PCB hole 

* 2 pieces transistor 2N3904 

* 2 pieces transistor 2N2907 

* 2 pieces Trimpot / potentiometer 50k-100k 

* 2 fruit 3.3K resistors 

* 2 fruit 1K resistor 

* 2 pieces LED (Light-emitting diode Emiting) 

* Spacer (PCB feet) 

* Robot Acrilic body diameter 20 cm. 

* Solder, tin solder and wires sufficiently 

* 6V battery box 

* Wheel marks reliever BB Rexona 

* 2 fruit DC motor with gearbox for GT1 and GT1 wheels 

Or 

* 2 fruit DC motor with gearbox and rubber Wheel GT5 to GT5 (even better) 

* PCB Drill 

* Glue Candle 

* Multitester analog / digital

Assembly 

The steps to assemble the robot is as follows: 

1. Prepare IC PCB holes, then fit and appropriate circuit components solderlah above. 

2. Give 6V voltage, set the light on the LDR provision by opening or closing the LDR surface with fingers or a paper, set trimpot / potentiometer so that the optimal results. This section is the most critical part in making robo tini, because if tuning is not right, aka robots are not suitable path beralan made. 




4. Put the PCB and its supporters acrilic. Connect the cable to the output DC motor PCB. Connected to the input battery 6V Supply PCB. 

 

5. If you've assembled on the floor try to run the already installed curved black lines (can use duct tape), then the robot will follow the path beralan. If the sensor is less sensitive, slowly rotate trimpot / potentiometer robot, for optimal results. LDR Make sure the sensor close enough to the floor. If the motor turns too fast, you can adjust the voltage of the DC motor, for example using a variable regulator IC LM317. 

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Know Your Light Sensor

Another type of resistor Light dependent resistor (LDR). LDR resistance changes with changes in light intensity about it. In the dark resistance of about 10MΩ LDR and in light of 1KΩ or less. LDR made from semiconductor materials such as cadmium sulfide. With this material the energy of the light that falls cause more load to the electric current is released or increased. This means that the material resistance has decreased. 

LDR is used to convert light energy into electrical energy. Automatic light switches and burglar alarms are a few examples of tools that use the LDR. However, because the response to light is slow, LDR is not used in situations where the intensity of light changed drastically. 



Function light sensor for detecting the light that surrounds us. Sensor to detect light famous is LDR (Light Dependent Resistor). The sensor will change its resistance value when there is a change in light brightness. 

These principles we will use to activate the transistor to a DC motor drive (similar to the dynamo in the toy cars children). Change the value of the LDR resistance will lead to changes in input voltage difference at the base of the transistor, so that will activate / disable transistors . Another application of this LDR sensor is in alarm Thief.

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Know Your Electronics Components

Resistor 

Resistors are electronic components that serves to provide resistance to the flow of electric current. In the electric circuit of resistors required certain specifications, such as major obstacles, the maximum current to be missed, and the characteristics of resistance against temperature and heat. Resistors provide resistance to a given component of the voltage current flowing through it is not large, and can be used as a voltage divider. 

Capacitors 

capacitor is an electrical component that serves to store electrical charges. One type of capacitor is keeping parallel capacitor. This capacitor consists of two parallel pieces of metal separated by an insulator called a dielectric. When the capacitor is connected to a battery-charged capacitor until the potential difference between the two terminals with battery voltage. If the battery is removed, electric charges will be exhausted in a very long time, except when a conductor is connected to the two capacitor terminals. 

Diodes 

Diodes are semiconductor devices that stream flow in one direction only. Diodes made of Silicon Germanium or better known as Junction diodes. Diode is also used on the adapter that functions as a rectifier of the AC signal to DC. 

  

LED (Light emitting diode) 

LED is a component that can emit light. LED is a product of the other findings after diode. The structure is also similar to the diode, but later found that the electrons that hit connection PN also releasing energy in the form of heat energy and light energy. LEDs are made to be more efficient if the issue of light. To obtain light emission in semiconductors, doping is the use of gallium, arsenic and phosporus. Different types of drugs produce different colors of light as well. 

At this time the colors of LED light that there is a lot of red, yellow and blue hijau.LED very rare. Basically, all colors can be produced, but it will be very expensive and inefficient. In addition to selecting the LED color, need to be considered working voltage, maximum current and power dissipation. 

Relay 

Transistor can not function as a switch (switch) DC voltage or high voltage. In addition, generally not used as a switch for large currents (> 5 A). In this case, the use of a perfect relay. Relay functions as a switch that works based on input he had. 

Benefits relay: 

· can switch AC and DC, DC transistor switches only 

· Relays can switch high voltages, transistors can not be 

· Relay choice for switching large currents 

· Relays can switch many contacts in the 1st time 

Lack of relay: 

· Relay size much larger than the transistor 

· Relay can not switch quickly 

· Relay need greater power compared to the transistor 

· Relay requires a large input current 


Transistor 

Bipolar transistors are used as electronic switches and amplifiers in digital electronic circuits. Transistor has 3 terminals. Transistors are usually made of silicon or germanium material. Three different foot shape is a bipolar transistor emitter, base and collector. They can be combined into NPN or PNP type which became one as the three legs of transistors. The figure below shows the shapes and symbols for NPN type. (The PNP transistors, emitter arrow opposite direction). 


 

Picture Symbols NPN and PNP transistors 


In electronic circuits, the input signal is 1 or 0 is always used at the base of the transistor, which the collector and emitter as a liaison to the breaker (short) or as the opening sequence. Rules / procedures transistor as follows: 

· NPN transistor, providing a positive voltage from the base to the emitter, causing the collector to emitter connections connected short, which causes the transistor active (on). Providing a negative voltage or 0 V from the base to the emitter causes the open collector and emitter, which is called the transistor die ( off) 

· In the PNP PNP transistors, providing a negative voltage from the base to the emitter of this transistor turns on (on). And provide a positive voltage or 0 V from the base to the emitter of this will make the transistor die (off).

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