Working of a Mobile charger - SIMPLIFIED

     Have you ever wondered how does a mobile charger works??? Most of us wouldn't have bothered about it. One need not be an electronics ninja to understand this. 

     First thing that we need to know about mobile phone chargers is that they are NOT 'chargers' at all!!!!!! They just serve as a power source to the charging circuitry that is contained within your mobile phone.

 Here is basic circuit diagram of a mobile charger.

It can be divided into four stages namely

 1. Step-down transformer 

 2. Bridge rectifier

 3. Filter circuit

 4. Voltage regulator (IC 7805)

STEP-DOWN TRANSFORMER

As the name suggests a step-down transformer 'steps down' the 220 V AC supply to 9 V AC. This is achieved by having lower number of coils in the secondary than in primary. As simple as that!!! Shown below is the image of an 9-0-9 centre-tapped step-down transformer.

RECTIFICATION

Rectification is the process of removing the negative half-cycle of AC & the device that does this is called a rectifier. A rectifier is usually made of uni-directional device called diodes. The diodes gets reverse biased during the negative half-cycle of the AC supply & since they don't conduct at reverse bias condition the negative half-cycle is converted into a positive one. Mobile chargers use a combination of four diodes (in the form of a bridge) to achieve rectification.

FILTER CIRCUIT STAGE

The output of bridge rectifier is actually not a proper DC waveform but an pulsating one. It is a partial DC that 'oscillates' just like an AC. So in order to make it truly a DC, we use capacitors to smoothen these oscillations & to remove ripples. Capacitors charge themselves what the waveform goes up & drains into the load (in this case the charging circuitry in the cell phone) when the waveform goes low. Thus it maintains the supply voltage at an almost constant value (i.e., DC output)

VOLTAGE REGULATION

This is the final stage of the charger circuit. IC 7805 is usually used as regulator that provides a steady 'regulated' 5 V DC. A capacitor is connected to the output of IC 7805 to eliminate noise. Shown below is an IC 7805 & its input-output waveform.

And finally this steady DC output of IC 7805 is fed to the batteries of our cell phones for 'charging'.

Thats all about mobile phone chargers

THOUGHT OF THE DAY

Choicest pics of India's own warbird Tejas PART-2

Choicest pics of India's own warbird Tejas PART-1

Rare image of INS Vikramaditya sailing alongside Russian aircraft carrier Admiral Kuznetsov!!!!!!!!!!!

 Shown above is a rare picture of India's INS Vikramaditya sailing alongside Russian aircraft carrier Admiral Kuznetsov

Three Nimitz super carriers in a single frame!!!!!!!!!!!!!!!

This is what makes US Navy the most dominant naval force on the planet........

  

CVN-70, Gipper & Stennis moored at NAS North Islands 

Japan will permanently join Indo-US naval exercises

    Much to the joy of defence enthusiasts in India, Japan has agreed to become a permanent participant of the Indo-US bilateral naval exercise 'Malabar'. Japan has sent its front line destroyer ship 'Fuyuzuki' to take part in Malabar 2015 which is being conducted in Bay of Bengal. 

    "MALABAR-15 will be another significant step in strengthening mutual confidence and inter-operability as well as sharing best practices between the Indian, Japanese and US navies," a joint press release issued by these navies said. This year's edition of Malabar will see USS Theodor Roosevelt in action. Indian Navy will be represented by INS Shivalik, INS Ranvijay, INS Betwa, INS Shakti, an Kilo-class submarine & a P-8 I reconnaissance aircraft.

 The Japanese destroyer that will take part in Malabar 2015 moored at Indian port city of Chennai

Japanese destroyer Onami during Malabar 2007

It is being speculated that these three nations are forging an alliance to counter China

Indian Navy's INS Satpura sailing alongside USS Carl Vinson during Malabar 2014

Indian Navy's INS Shakti tanker ship refueling USS Carl Vinson during Malabar 2014

India advances strategic partnership with Turkey

     As part of Indian Navy's overseas deployment to West Asia, its front line warship INS Trikhand made port call at Istanbul's Sarayburnu Port from Oct. 4 to 7. INS Trikand's visit to İstanbul closely follows the visit of Turkish frigate TCG Gediz, which made port calls at Mumbai and Chennai in India in April and July, respectively, this year. 

     

     Speaking during a reception on the INS Trikand at Sarayburnu Port on Monday, Capt. Vinay Kalia said the visit seeks to underscore India's peaceful presence and solidarity with other countries and strengthen the existing bonds between India and Turkey. Kalia said Indian naval assets are regularly deployed as part of the Indian Navy's mission to build “bridges of friendship” and strengthen international cooperation with friendly countries, as well as address maritime concerns of the region, including piracy in the Gulf of Aden.

INS Trikhand entering port of Istanbul

INS Trikhand at Istanbul port

INS Trikhand in Anti-Piracy operation in Gulf of Aden

Turkish frigate TCG Gediz that visited India during April of this year

Great shot of BrahMos block-III missile test firing

     Indian Army on May 8 successfully test fired its BrahMos (block-III) supersonic cruise missile.

 

     BrahMos has been inducted into Navy & Army & its air-launched version (ALCM) for Air Force will be ready for testing in a year or two. So far the missile has been tested 47 times out of which 45 tests have been successful. Developed as a JV between India & Russia, this 'precision strike weapon system' is among the most reliable & sophisticated missile in the world. Impressed by its performance the Indian Navy  placed orders for 49 BrahMos missiles at a cost of INR 711 crores & the Indian Army to its part placed orders for 134 BrahMos missiles at a cost of INR 8,352 crores.

    

     Here is a great shot of India's supersonic cruise missile BrahMos being test fired successfully.

India's first indigenous aircraft carrier 'INS Vikrant' undocked

     India recently achieved a remarkable feat which went largely unnoticed as media-houses were busy covering Indian Army's daring cross-border surgical strike in Myanmar. India's first indigenous aircraft carrier (IAC-1)  'INS Vikrant' was undocked at Cochin Shipyard Ltd., (CSL) marking the completion of phase-II of construction. 'INS Vikrant' will be the replacing Indian Navy's ageing INS Viraat aircraft carrier whose decommissioning is now scheduled for 2018. INS Vikrant which displaces some 40,000 tonnes & has a length of 262 metres is the largest ship ever built by an Indian shipyard & is among only seven aircraft carriers in the world that are under construction as of 2015. This mega-ship is being built at a cost of INR.20,000 crores. This ship is designed to host a maximum of 30 fixed-wing aircrafts (such as Mig-29K/KUB & HAL Tejas) & will have a maximum range of 15,000 Kms.
     

     INS Vikrant will be armed heavily with four OTO Melara 76 mm naval guns & AK-630 CIWS besides using state-of-the-art Barak-8 surface-to-air missiles (SAMs) to take on aerial targets. It will also be equipped with EL/M 2248 (S-band) & Selex RAN-40 (L-band) AESA radars that are capable of detecting aircrafts/drones upto 400 Kms away. This ship will augment Indian Navy's power projection capabilities as far as South China Sea & East China sea.

When completed INS Vikrant will look like this

 INS Vikrant being undocked at CSL

INS Vikrant after being undocked

Rear view of INS Vikrant

Eagle's eye view of INS Vikrant before being undocked