Mobile Phone Battery Charger with Emergency Light[DIY]

           Mobile Phone Battery Charger with Emergency Light[DIY]

Contents 

·         1 Mobile Phone Battery Charger Circuit Diagram:

o    1.1 Circuit Components:

o    1.2 Working of Mobile Phone Battery Charger Circuit:

A very easy circuit of “variable power supply and charger” is being explained here. It is not only very much useful in the time of power cut but also used as main power supply. At your workbench you can use this circuit to check or testing of your electronic projects. Mobile phone batteries can be charged with the help of these circuits. This circuit can work as an emergency light.

Mobile Phone Battery Charger Circuit Diagram:

                                                   

Mobile Phone Battery Charger Circuit

Circuit Components:

·         LM317 – 1

·         Resistor

·         R1 (220E) – 1

·         R2-R12 (220E) – 11

·         R13 (470E)

·         VR1 (100K) – 1

·         C1 (100uF) – 1

·         C2 (. 1uF) – 1

·         D1-D4 (1N4007) – 4

·         S1-S5 (on/off switch) – 5

·         LED1-LED12 – 12

·         Transformer – 1

·         Battery – 1

·         Zener diode (3.3) – 1

Components Description:

1.   LM317: It is a variable voltage supplier. It is a device with three terminals. It works on voltage range of 1.25 V to 37 V at a current of 1.5 amps.

2.   Resistor– The flow of current in any of the circuit is being controlled by the resistor. It is basically a passive device. There are two types of resistor available i.e

1.   Fixed Resistor – whose value of resistance is fixed

2.   Variable Resistor – whose value of resistance can vary

3.   Capacitor– It is used to store the electrical charges . It is also a passive device and are available in the market in two types i.e.

1.   Polarized Capacitor – Capacitors with polarity i.e. have + and – terminal eg electrolytic capacitor

2.   Non-Polarized Capacitor – Capacitor without any polarity e.g. ceramic and paper capacitor.

4.   Diode – It is mainly used to allow the single directional flow of current. It is a passive device with two terminals.

5.   Switches -Literal sense of a switch is “transform of state”. In an electrical logic, ON and OFF are the two conditions and switch assist to alter the condition of an electrical machine from ON to OFF or reverse. Firmly talking, it doesn’t turn on or off the machine; it merely creates or break the contact.

6.   LED (Light emitting diode) – It is a semiconductor device that produces a diverse source of beam at its output. When they are electrically biased in the forward state of p-n junction it emits a narrow spectrum of light. LED are found in the market very easily in a variety of colors via red, yellow, green and many more like white, orange etc.

7.   Transformer -A transformer  is a device which is used for transforming current from one circuit to another.  During the transformation process, characteristic of AC signal changes. For example a low voltage AC may be changed to a high voltage AC and vice versa. The working of the transformer is based on the magnetic field to build around the conductor when current flows through it. This principle is called as electromagnetic mutual induction. Transformers are made up of two coils of wire wrapped around a core.

8.   Battery – Battery is mainly a group of one or more than one electrochemical cell and in that chemical energy that is already stored is turned into electrical energy. From the age of Volta the principles of operation have not been altered. Every cell in the battery is made up of two halves of cells which are linked in series via an electrolytic solution. While 1/3 of the cell is made up of two houses named as the anode and cathode positive ions of the anode roam from the electrolyte to the cathode.

9.   Zener Diode – This diode work in the reverse bias  state and start conducting when the voltage achieves the break point. If you want to get stable voltage then all you need is to  couple a resistor across it so that current flow can control.

Working of Mobile Phone Battery Charger Circuit:

As per your need you can take the output from  the circuit by just  flipping the different number of switches (from S3, S4 and S5) in the circuit. If you require the variable power supply as your output than set switch S3 into “on” state. LM317 is used in the circuit which is a variable voltage regulator to  supply variable power. The LM317 is basically positive voltage regulator has three terminals. 1.2 V to  37V is the range of the output  voltage that is provided by the LM317. Different range of voltage can be achieved by just  adjusting  the variable resistor that is provided in the circuit and with the help of multimeter output can be seen and the voltage which is desirable can set. The power supply range  can altar from 1.5V to  12V.

With the help of flipping the S5 switch which is provided in the circuit Li-ions  battery can be charged, which are generally used in the mobile phones with the assist of your mobile connectors. While the charging current in the circuit  is being controlled with the help of resistor R13. Turn over to switch S5 if you want  to use the emergency light. Reflectors can be used in the circuit if you wish to enlarge the intensity of light.

S1 and S2 are the two switches that are given in the circuit so that you can power your circuit either directly with the AC supply or else you can take help of any battery. If you want to use an AC supply than flip to switch S1 while if you want to have supplied from the battery than flip to switch S2. In the place  of  AC power supply solar panels can be used and for storing the charge you can take rechargeable batteries, this will not merely save electric bill but also assist you a lot in the state of power failure.

  

DECLARATION:
OUR BLOG IS NOT FOR COMMERCIAL PURPOSE.ONLY FOR EDUCATIONAL PURPOSE.ALL CREDITS GOES TO BLOG AND RESPECTIVE AUTHOR.CLICK HERETO GO ORGINAL PAGE.

Smoke Detector Alarm Circuit[DIY]

                Smoke Detector Alarm Circuit[DIY]

Contents 

·         1 A Brief Introduction to Smoke Sensor

·         2 Circuit Diagram

·         3 Components Required

·         4 Working

A Smoke Detector is a smoke sensing device that indicates fire. Smoke Detectors are very common in homes, offices, schools and industries. Smoke Detectors are very useful devices as the damage caused by fire accidents is catastrophic.

Now a days, smoke detectors and smoke alarms are very cheap as its usage is increasing and cost of manufacturing is decreasing. In this project, we are implementing a simple Smoke Detector Circuit using simple hardware.

We used a Gas/Smoke sensor for detecting smoke. The article is divided into information about Smoke sensor, circuit diagram and working.

                                                        

A Brief Introduction to Smoke Sensor

There are two types of smoke detectors. Optical or Photoelectric smoke detectors and Ionization smoke detectors.
Optical smoke detectors consists of a light source like LED and a light detector like photocell.

The photocell conducts as long as the light falls on it. When there is smoke, the light from the source is interrupted and the photocell doesn’t conduct.

Ionization smoke detectors consists of two electrodes and an ionization chamber filled with ions. When there is no smoke, the ions move freely and the electrodes conduct normally.

In the presence of smoke, the chamber is filled with smoke and interrupts the movement of ions. The electrodes do not conduct anymore. Depending on the type of sensor and manufacturer, the conductivity conditions may change but the idea remains the same.

Based on the output of the smoke detector, an alarm system can be implemented.

The sensor used in this project is MQ-2 Gas/Smoke sensor. It is sensitive to LPG, Hydrogen, Smoke, Methane, Propane, Alcohol, Butane and other industrial combustible gases.

It has two electrodes made of Aluminum Oxide (Al2O3) and a heating element made of Tin dioxide (SnO¬2) which acts as the main sensing layer.

Circuit Diagram

                                                            

Components Required

·         MQ-2 Sensor

·         LM358

·         10KΩ

·         330Ω

·         LED

·         0.1µF

·         10KΩ POT

Working

Smoke Detectors are amazing devices as they are small, cheap yet very useful. In this project, we implemented a simple Smoke Detector Circuit with adjustable sensitivity.

We used a Smoke Sensor MQ-2 as the main sensory device. The working of the circuit is simple and is explained below.

LM358 acts as a comparator in this circuit. The inverting terminal of LM358 is connected to POT so that the sensitivity of the circuit can be adjusted.

The output of LM358 is given to an LED as an indicator although a buzzer can be used as an alarm. The non-inverting terminal of LM358 is connected with output of smoke sensor.

Initially, when the air is clean, the conductivity between the electrodes is less, as the resistance is in the order of 50KΩ. The inverting terminal input of comparator is higher than the non-inverting terminal input. The indicator LED is OFF.

In the event of fire, when the sensor is filled with smoke, the resistance of the sensor falls to 5KΩ and the conductivity between the electrodes increases.

This provides a higher input at the non-inverting terminal of comparator than the inverting terminal and the output of comparator is high. The alarming LED is turned ON as an indication of presence of smoke.

Note

·         The heating element in the Smoke Sensor must be preheated before it can sense any smoke or gas.

·         The sensor gets hot because of the heating coil and it is advised not to touch the sensor while it is switched on.

·         The sensitivity of the circuit to different concentrations of smoke can be adjusted by using the POT.

·         The output LED can be replaced with a loud buzzer for effective alarm.

DECLARATION:
OUR BLOG IS NOT FOR COMMERCIAL PURPOSE.ONLY FOR EDUCATIONAL PURPOSE.ALL CREDITS GOES TO BLOG AND RESPECTIVE AUTHOR.CLICK HERETO GO ORGINAL PAGE.

12V DC to 220V AC Converter[DIY]

                              12V DC to 220V AC Converter[DIY]

Contents 

·         1 Principle Behind this Circuit

·         2 Inverter circuit Using Transistors

o    2.1 Circuit Diagram

o    2.2 Components required

o    2.3 Working

·         3 12v DC to 220v AC Converter Circuit Using Astable Multivibrator

o    3.1 Circuit Design Explanation

o    3.2 12v DC to 220v AC Converter Circuit Operation

o    3.3 Applications of 12v DC to 220v AC Converter Circuit

o    3.4 Limitations

Inverters are often needed at places where it is not possible to get AC supply from the Mains. An inverter circuit is used to convert the DC power to AC power. Inverters can be of two types True/pure sine wave inverters and quasi or modified inverters. These true /pure sine wave inverters are costly, while modified or quasi inverters are inexpensive.

These modified inverters produce a square wave and these are not used to power delicate electronic equipments . Here, a simple voltage driven inverter circuit using power transistors as switching devices is build, which converts 12V DC signal to single phase 220V AC.

Principle Behind this Circuit

The basic idea behind every inverter circuit is to produce oscillations using the given DC and apply these oscillations across the primary of the transformer by amplifying the current. This primary voltage is then stepped up to a higher voltage depending upon the number of turns in primary and secondary coils.

Inverter circuit Using Transistors

                                                        

A 12V DC to 220 V AC converter can also be designed using simple transistors. It can be used to power lamps up to 35W but can be made to drive more powerful loads by adding more MOSFETS.

The inverter implemented in this circuit is a square wave inverter and works with devices that do not require pure sine wave AC.

Circuit Diagram

                                                        

Components required

·         12v Battery

·         MOSFET IRF 630 -2

·         2N2222 Transistors

·         2.2uf capacitors-2

·         Resistor

·         680 ohm-2

·         12k-2

·         12v-220v center tapped step up transformer.

·         2N2222 Datasheet

·         IRF630 Datasheet

Working

The circuit can be divided into three parts: oscillator, amplifier and transformer. A 50Hz oscillator is required as the frequency of AC supply is 50Hz.

This can be achieved by constructing an Astable multivibrator which produces a square wave at 50Hz. In the circuit, R1, R2, R3, R4, C1, C2, T2 and T3 form the oscillator.

Each transistor produces inverting square waves. The values of R1, R2 and C1 (R4, R3 and C2 are identical) will decide the frequency. The formula for the frequency of square wave generated by the astable multivibrator is

F = 1/(1.38*R2*C1)

The inverting signals from the oscillator are amplified by the Power MOSFETS T1 and T4. These amplified signals are given to the step-up transformer with its center tap connected to 12V DC.

The turns ratio of the transformer must be 1:19 in order to convert 12V to 220V. The transformer combines both the inverting signals to generate a 220V alternating square wave output.

By using a 24V battery, loads up to 85W can be powered, but the design is inefficient. In order to increase the capacity of the inverter, the number of MOSFETS must be increased.

12v DC to 220v AC Converter Circuit Using Astable Multivibrator

Inverter circuits can either use thyristors as switching devices or transistors.  Normally for low and medium power applications, power transistors are used. The reason for using power transistor is they have very low output impedance, allowing maximum current to flow at the output.

One of the important applications of a transistor is in switching.  For this application, the transistor is biased in saturation and cut-off region.

When the transistor is biased in saturation region, both the collector emitter and collector base junctions are forward biased. Here the collector emitter voltage is minimum and collector current is maximum.

Another important aspect of this circuit is the oscillator. An important use of 555 Timer IC is in its use as an astable multivibrator.

An astable multivibrator produces an output signal which switches between the two states and hence can be used as an oscillator. The frequency of oscillation is determined by the values of capacitor and resistors.

 Circuit Diagram

                                                        

Circuit Diagram of 12v DC to 220v AC Converter

Circuit Components

·         V1 = 12V

·         R1 = 10K

·         R2 = 150K

·         R3 = 10Ohms

·         R4 = 10Ohms

·         Q1 = TIP41

·         Q2 = TIP42

·         D1 = D2 = 1N4007

·         C3 = 2200uF

·         T1 = 12V/220V step up transformer

Circuit Design Explanation

Oscillator Design: An astable multivibrator can be used as an oscillator. Here an astable multivibrator using 555 timer is designed. We know, frequency of oscillations for a 555 timer in astable mode is given by:

f = 1.44/(R1+2*R2)*C

where R1 is the resistance between discharge pin and Vcc, R2 is the resistance between discharge pin and threshold pin and C is capacitance between threshold pin and ground.  Also the duty cycle of the output signal is given by:

D = (R1+R2)/(R1+2*R2)

Since our requirement is f =50Hz and D = 50% and assuming C to be 0.1uF, we can calculate the values of R1 and R2 to be 10K and 140K Ohms respectively. Here we prefer using a 150K potentiometer to fine tune the output signal.

Also a ceramic capacitor of 0.01uF is used between the control pin and ground.

Switching Circuit Design:Our main aim is to develop an AC signal of 220V. This requires use of high power transistors to allow the flow of maximum amount of current to the load. For this reason we use a power transistor TIP41 with a maximum collector current of 6A, where the base current is given by the collector current divided by the DC current gain.  This gives a bias current of about 0.4A *10, i.e.4A. However since this current is more than the maximum base current of the transistor, we prefer a value less than the maximum base current. Let us assume the bias current to be 1A. The bias resistor is then given by

R_b = (V_cc – V_BE(ON))/I_bias

For each transistor, the V_BE(ON) is about 2V. Thus R_b for each is calculated to be 10 Ohms. Since the diodes are used for biasing, the forward voltage drop across the diodes should be equal to the forward voltage drops across the transistors. For this reason, diodes 1N4007 are used.

The design considerations for both the PNP and NPN transistors are same. We are using a PNP power transistor TIP42.

Output Load Design: Since the output from the switching circuit is a pulse width modulated output, it might contain harmonic frequencies other than the fundamental AC frequency. For this reason, an electrolyte capacitor needs to be used to allow only the fundamental frequency to pass through it. Here we use an electrolyte capacitor of 2200uF, large enough to filter out the harmonics. Since it is required to get 220V output, it is preferred to use a step up transformer. Here a 12V/220V step up transformer is used.

12v DC to 220v AC Converter Circuit Operation

·         When this device is powered using the 12V battery, the 555 timer connected in astable mode produces square wave signal of 50Hz frequency.

·         When the output is at logic high level, diode D2 will conduct and the current will pass through diode D1, R3 to the base of transistor Q1.

·         Thus transistor Q1 will be switched on. When the output is at logic low level, diode D1 will conduct and current will flow via and D1 and R4 to the base of Q2, causing it to be switched on.

·         This allows the DC voltage to be produced across the primary of the transformer at alternate intervals. The capacitor ensures that the frequency of the signal is at the required fundamental frequency.

·         This 12V AC signal across the primary of the transformer is then stepped up to 220V AC signal across the transformer secondary.

Applications of 12v DC to 220v AC Converter Circuit

1.   This circuit can be used in cars and other vehicles to charge small batteries.

2.   This circuit can be used to drive low power AC motors

3.   It can be used in solar power system.

Limitations

1.   Since 555 Timer is used, the output may slightly vary around the required duty cycle of 50%, i.e. exact 50% duty cycle signal is hard to achieve.

2.   Use of transistors reduces the efficiency of the circuit.

3.   Use of switching transistors has the possibility of causing cross over distortion in the output signal. However this limitation has been reduced to some extent by the use of biasing diodes.

Note

Instead of 555 timer one can use any astable multivibrator. For example this circuits can also be build using 4047 astable multivibrator,whose output current is amplified and applied to the transformer.

DECLARATION:
OUR BLOG IS NOT FOR COMMERCIAL PURPOSE.ONLY FOR EDUCATIONAL PURPOSE.ALL CREDITS GOES TO BLOG AND RESPECTIVE AUTHOR.CLICK HERETO GO ORGINAL PAGE.