# INTRODUCTION :

### 555 timer is one of the most versatile linear integrated circuits. Signetics corporation first introduced 555 timer as SE/NE 555 in early 1970.Since its debut,the device is being used in a number of novel and useful applications.This is an eight pin Integrated circuit ( IC ) package and used in making 555 projects.

`why it is called 555 timer?`

This is called 555 timer because in the circuit design it use three resistors of 5 KΩ. The 5 of every resistor is grouped  and so it is called 555 and due to its time delays furthermore it is called 555 timer. These resistors also provide voltage division in the circuit.

Above diagram is the internal circuit of the 555 timer but in its use the circuit is abstract therefore we work only with the pins for the reason that  to reduce complexity .

This is the pin diagram of the 555 timer and first of all try to learn the basic points and After getting the basic knowledge you can start making projects:

# 1.BLINKING LED  IN 555 PROJECTS:

555 timer ‘s best and simple project is blinking of LED. This project is in the first place when making project on this IC. Components required  for this project:

1. One 555 timer IC
2. Some resistors and capacitors( 1kΩ , 470kΩ , 1µf )
3. Jumper wires(male to male)
4. Power Supply and Led

First of all put the 555 timer IC onto the breadboard and pins should be at different potentials and make the connections according to the diagram shown below and on giving the power supply , the 555 will produce a delay and as a result led will start blinking.

By changing the values of R1 ND R2 we and C1 we can change the time delays because time of charging and discharging are dependent on them tc=0.693(R1+R2*.C1 and td=0.693*R2*C1 .This is considered to be the one of the simplest project due to the simplicity of the design .

# 2.SQUARE-WAVE GENERATOR IN 555 PROJECTS:

This is the second  recommended project because of the simplicity of design and ease of working is quite high. A square wave generator is a circuit which produces square wave forms  on applying analog input. A square wave generator is an important tool in the experiments of subjects like (Digital Electronics , Electronics and devices). The components required are as follows :

2. Jumper wires(Male to Male)
3. few capacitors(1kΩ,470kΩ,1µF)
4. One Ne 555 IC
5. Power Supply(5 volt)
6. CRO (for checking the output)

# 3.Motion Detector IN 555 PROJECTS:

This circuit works along with the Passive Infrared sensor which automatically activates a device when the distance is very small to the circuit . For the security purpose and to keep a check on thief motion detector is very practical because of the efficiency of the circuit. It turns on the lights when someone come closer to the circuit . This circuit is mainly used for security systems, corridor lights and bathroom lights .

2. Jumper wires(Male to Male)
3.  Capacitors and resistors
4. One Ne 555 IC
5. One 7806 IC
6. Transformer (230 v ,50 hertz)
7. BC547 transistor (NPN)
8. Power Supply
9. P-N diode
10. Led

However Motion detector design requires some basic knowledge of working principle of transformers .

# 4. Sound Timer IN 555 PROJECTS:

This  circuit is based on LM324 quad-operational amplifier and NE555 timer. Time delay can be reduced or increased according to the combination of resistor or capacitor from few seconds to 30 minutes. A sound sensitive burglar alarm uses a sound timer. A single side PCB layout for the sound operated timer and its component layout is also provided. After assembling the circuit on the PCB, enclose it in a suitable plastic box. The components required for the project are:

1. Jumper wires(Male to Male)
2.  Capacitors and resistors
3. One Ne 555 IC
4. Ic LM324
5. Transformer (230 v ,50 hertz)
6. Condenser
7. Power Supply
8. P-N diode
9. ON/OFF switch
10. PCB

While this circuit is also complicated to design, it is very useful during our student life.

# 5.SEQUENTIAL TIMER FOR DC MOTOR IN 555 PROJECTS:

The most simple sequential timer can be developed using NE555 ICs wired in monostable mode. Cascading a number of these monostable stages forms a sequential timer. The output of one stage is applied as the trigger to the next stage. So, when the output of a stage drops, it triggers the next stage and the output of the next stage goes high, and likewise the chain reaction starts. The components required :

1. Jumper wires(Male to Male)
2.  Capacitors and resistors
3. One Ne 555 IC
4. Transformer (230 v ,50 hertz)
5. Power Supply
6. Dc motor
7. PCB

This is the last project in my list because of its design structure i will prefer you not to start in the beginning stage but once you become a veteran you must do this for more knowledge.

For more projects you can also visit :

Simple projects engineers can do in less funds

Latest Microcontroller Projects for Engineering Students

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