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Cell Phone Detector Circuit


The most common electronic equipment used is cell phones. With advancement in communication technology, the requirement of cell phones has increased manifold. A cell phone typically transmits and receives signals in the frequency range of 0.9 to 3GHz. This article provides a simple circuit to detect the presence of an activated cell phone by detecting these signals.

Basic Principle of Mobile Phone Detector Circuit:

The basic principle behind this circuit is the idea of using a Schottky diode to detect the cell phone signal. Mobile phone signal is in the frequency range of 0.9 to 3GHZ.  Schottky diodes have a unique property of being able to rectify low frequency signals, with low noise rate. When an inductor is placed near the RF signal source, it receives the signal through mutual induction. This signal is rectified by the Schottky diode. This low power signal can be amplified and used to power any indicator like an LED in this case.
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Ninja Blast

Water Level Controller using 8051 Microcontroller


This system mainly works on a principle that “water conducts electricity”. The four wires which are dipped into the tank will indicate the different water levels. Based on the outputs of these wires, microcontroller displays water level on LCD as well as controls the motor.

Circuit Components:
  • At89c51 controller
  • At89c51 programming board.
  • 16*2 LCD
  • 5V Relay
  • Bc547 (NPN) transistors – 5
  • Resistors (1K) – 4
  • Resistor – 330 ohm
  • AC Motor
  • Pot – 10k
  • Programming cable
  • Connecting wires

Water Level Controller using 8051 Circuit Design:

The main heart of this project is AT89C51 microcontroller. The water level probes are connected to the P3.0, P3.1, P3.2, and P3.3 through the transistors. Port P2 connected to the data pins of LCD and control pins RS, RW and EN of LCD are connected to the P1.0, P1.1, and P1.2 respectively.
Initially when tank is empty, LCD will display the message EMPTY and motor runs automatically. When water level reaches to quarter level, now LCD displays QUARTER and still motor runs. For further levels, LCD displays the messages HALF and ¾ FULL.
When tank is full, LCD displays FULL and motor automatically stops. Again motor runs when tank is empty.
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Unknown

1 - 30 Minutes Timer Circuit

In this circuit you can switch on an appliance for a desired time. The circuit provides selectable time settings of 1, 2, 5, 10, 15 and 30 minutes, and can be used for domestic as well as industrial applications.

The circuit can be divided into two sections—power supply and timer. The power supply is built around transformer X1, bridge rectifier BR1, capacitor C1 and 12V voltage regulator IC LM7812 (IC1). The 230V AC mains supply is stepped down by transformer X1 to deliver the secondary output of 12V, 250 mA. The transformer output is rectified by full-wave bridge rectifier BR1, filtered by capacitor C1 and regulated by IC1. The circuit can also be powered by a 12V battery. The power source can be selected by using switch S2.


CIRCUIT DIAGRAM

The timer section is built around IC NE555 (IC2) along with resistors R1 through R6, capacitor C2, transistor BC548 (T1) and a 12V relay. IC2 is configured in monostable mode to provide the different time settings ranging from 1 to 30 minutes. The desired time is selected by rotary switch S1 as shown in the table. Pressing switch S3 starts the operation. Once triggered, the timer returns to its original state after the preset time. 
Working of the circuit is simple. Capacitor C2 charges through a resistor or combination of resistors R1 through R6. When start switch S3 is pressed, the monostable triggers and its output pin 3 goes high for the time selected by the position of rotary switch S1. The output time (T) of the monostable in seconds is T =1.1RC.

Assemble the circuit on a general-purpose PCB and enclose in a suitable case. Fix the unit near the appliance that has to be controlled. Use a 12V relay (RL1) with contact current rating suited for the the appliance.
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Automatic Earth Fault Indicator



In mains-powered equipment, exposed metal parts are connected to earth wire in order to prevent users from contact with high voltages if electrical insulation fails. Connections to ground through earth connection also limit the build-up of static electricity when handling electrostatic-sensitive devices. Earth in a mains electrical wiring system is a conductor that provides a low-impedance path to the earth to prevent hazardous voltages from appearing on equipment and hence the name.

Here is a simple tester to find whether the mains wiring is correct or not. This tester can be used to check sockets periodically before connecting appliances like heater and electric iron. It indicates the status of the mains wiring through two LEDs



CIRCUIT DIAGRAM

Circuit and working: The circuit is built around a BC547 transistor (T1), two LEDs (LED1and LED2), two 1N4007 diodes (D1 and D2) and five resistors (R1 through R5).The circuit takes advantage of the voltage that appears across the earth and neutral terminals. Neutral-to-earth voltage as measured at the load for a single-phase circuit is a function of the load current and the impedance of the neutral wire. Various standards limit this voltage drop in a branch circuit to 3 per cent (5 per cent total for feeder and branch circuit) for a reasonable efficiency of operation. Based on this, the neutral-to-earth voltage limit for a single-phase 120V AC circuit is 3.6V AC and for a single-phase 230V AC circuit 6.6V AC.

There is no additional power supply used to operate this circuit. The circuit is directly powered from the 230V AC mains supply. The combination of diode D1 and resistor R1 reduces the 230V AC mains to a low voltage for the circuit. A transistor switch is provided to light up the green LED (LED1) if earth is correctly connected. The base of T1 is connected to earth pin of the mains supply through a network of resistors R2 and R3.

Working of the circuit is simple. The red LED (LED2) lights up if there is power in the socket and phase (L) and neutral (N) lines are connected correctly. Diode D2 protects the green LED (LED1) from damage when the polarity changes. Resistors R4 and R5 limit current through LED1 and LED2, respectively.

When the mains wiring is proper, a potential difference develops between the neutral (N) and earth (E) lines and transistor T1 turns on to light up the green LED (LED1). This indicates that the earth connection is perfect. At the same time, the red LED also glows, indicating that the phase (L) and neutral (N) lines are connected properly. In brief, if the phase, neutral and earth connections are proper, both the red and green LEDs light up. When the earth connection is broken, the red LED2 glows but green LED1 does not.

Construction and testing: An actual-size, single-side PCB for the earth fault indicator and its component layout. After assembling the circuit on a PCB, enclose it in a suitable plastic case. The circuit can be housed in an adaptor box with three pins.To test the circuit for proper functioning, check input supply at TP1 with respect to TP0. Also check the voltage difference across neutral and earth pins as per the test point table.
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Ninja Blast

Airtel Immediate Job Recruitment for 2015 || Freshers/Any Graduate – Apply Now



Company: Airtel

About Airtel:
Bharti Airtel Limited is an Indian multinational telecommunications services company headquartered in New Delhi, India. It operates in 20 countries across South Asia, Africa, and the Channel Islands. 

Website: www.airtel.in

Job Role: Telecalling/Telemarketing Executive

Qualification: Any Graduate

Experience: 0 – 1 Years

Industry: BPO/Call Centre/ITES

Functional Area: ITES , BPO , KPO , LPO , Customer Service , Operations

Role Category: Voice

Work Location: Delhi

Pay Scale: INR 1,25,000 - 3,50,000 P.A

Skills: Good Communication

Hiring Mode: Interview

Apply Mode: Online
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Ninja Blast

Reliance Industries Ltd Urgent Recruitment for Freshers (2013,2014,2014,2015 Batch) – Apply Online



Company: Reliance Industries Ltd

About Reliance:
Reliance Industries Limited is the largest private sector corporation in India with annual revenue of US$ 62.2 billion and net profit of US$ 3.8 billion. The Group's activities span hydrocarbon exploration and production, petroleum refining and marketing, petrochemicals, retail and telecommunications. Reliance Industries Ltd is India's first private sector company to feature in Fortune Global 500 list of 'World's Largest Corporations', currently ranking 114th in terms of revenue & 155th in terms of profit. RIL strives to be a product and service leader across its industries, a great work-place and above all, to create value for its stakeholders and society.

Website: www.ril.com

Job Role: Fresher

Qualification: Any Graduate

Experience Required: Freshers

Salary: Best in Industry

Functional Area: Fashion Designing, Merchandising

Industry: Internet/Ecommerce

Role Category: Other

Required Documents: Resume

Selection Process: Easy and Fast Selection

Apply Mode: Online
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Ninja Blast

Vodafone Recruitment Drive for 2015 – 2016 || Freshers/Huge Vacancies – Apply Now



Company: Vodafone

About Vodafone:
At Vodafone India, our customers are at the heart of everything we do. That’s why over 180 million Indians have chosen to stay connected with us.

Our knowledge of global best practices along with our deep exposure to local markets has made us leaders in the telecommunications industry. Since commencing operations in 2007, we have consistently been awarded for our best-in-class network, powerful brand, unique distribution and unmatched customer service. Whether an individual or enterprise, our customers always receive world-class services that cater to their needs.

Website: www.vodafone.in

Job Role: Associate

Qualification: Any Graduate

Experience: Freshers

Work Location: Ahmadabad

Induatry Type: IT

Salary:  Good

Skills:
Excellent communication skills, analytical skills and should be a team player, experience with chat enviroment

Behavioral/Personality Specifications Required:
Good Typing skills
Good communication skills
Good convincing power
Good vocabulary

Shift: Rotational

Documents Required: Updated CV

Vodafone Selection Process:
Aptitude Test
Technical Interview
HR Interview

Apply Mode: Online
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