Tuesday, 18 November 2014

Make a PWM Controlled Cell Phon Battery Charger using IC555

How to Make a Simple PWM Controlled DC to DC Cell Phone Charger Circuit vy using IC 555 at Home

Today we are going to learn how to make a very simple PWM DC to DC Cell phon charger circuit. The circuit is a simple cell phone charger that may be operated with any DC source, from a car or a motorcycle battery or from any ordinary 12 V AC DC adapter. Nowadays we find most of the vehicles have their in built cell phone battery charger units which surely becomes very handy for travelers who mostly remain outdoors travelling in their vehicle.
This PWM cell phone battery charger circuit is as good as the conventional chargers which come fitted inside the cars and bikes. Moreover the circuit can be simply integrated to ones own vehicle if the feature is not originally available in the vehicle. Alternatively one may think of manufacturing the present unit and selling them in the market as an automobile cell phone charger and earn some hard bucks.

Circuit Description

Cell phones as we all know are highly sophisticated and useful gadgets and when it comes to charging cell phones battery and needs a very high standards of current and voltages for charging them.

The AC/DC cell phone chargers which come with the cell phones are all SMPS based and are extremely good with their outputs and that’s why the cell phone gets so efficiently charged by their chargers.

Cell phone battery cannot just be charged by supplying DC 4 volts, unless the current is optimally dimensioned  according to the specific value.

The PWM controlled DC to DC cell phone battery charger circuit is very efficient because, the involvement of PWM pulses helps to keep the output very suitable to the cell phone circuitry and also the concept involves no heating of the output device, making the entire circuit truly efficient.
From the circuit diagram we find that again the work horse IC 555 comes to our rescue and performs the important function of generating the required PWM pulses.

The input to the circuit is supplied through some standard DC source, ideally from an automobile battery 12v or 9 volt or any above 5 volt.

The voltage powers the IC which instantly starts generating the PWM pulses and feeds it to the components connected at its output pin #3.

At the output the power transistor is used for switching the DC voltage at its collector directly to the cell phone.

However only the average DC voltage is finally fed to the cell phone due to the presence of the filter 10uF capacitor, which effectively filters the pulsating current and provides a smooth ripple free, standard 4 volts to the cell phone.

After the circuit is built, the given pot will need to be optimized perfectly so that a well standard voltage  is produced at the output which may be ideally suited for charging the specific cell phone battery.

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