Converter 12 Volt to 5 Volt




About: I am a student of BSCS but I'm interested in electronics that's why I would like to think about innovative ideas and try to build my ideas into reality and i also interested in making a robots. email id: deg...

Hello! friends welcome to my another project. In this project i'm gonna show you how to charger your smartphones. If you don't have your smartphone charger then no problem with the help of the gadget you can charge your smartphone very easily. The input of this converter is not more than 12 volt or you can use 9 volt also but in case of 9 volt the charging time is definitely increased. You can use any 12 volt charger like routers, switches etc.

So let's get started...

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Step 1: Circuit Diagram

Here it is the circuit diagram. We can build our tiny little converter with the help of this diagram.

Step 2: Components

You'll need

small piece of vero board

A candy box (you can buy your nearest candy shop)

Female usb port

12 volt female connector according to your charger

IC: LM7805

Capacitors: 100nf x 2 (non-polarized), 100uf (polarized) and 47uf (polarized)

Resistors: 1k and 470 ohms

Led: Red

Spst on/off switch

Step 3: Placing and Soldering Components

place your components according to circuit diagram and then soldering it very carefully don't forget to soldering a female usb port and a switch in a candy box cap.

Step 4: Fitting

Now fit your chip into a candy box and make hole at the end of the box for input.

Step 5: Finish

Finally your 12 volt to 5 volt portable gadget is look like this.

I hope you guys like it.

Thanks for watching.

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    21 Discussions


    4 years ago on Introduction

    FYI, the reason that 9V batteries are so bad is that they only manage about 300mAH.

    Very nice project.

    10 replies

    johanmoberg i just simply download a circuit from google and build this can you tell my how to increase the amp of this upto 1 or 1.5 if know about this please explain me.BTW thanks

    Ok, you acctually only need the LM7805. You could add a capacitator for filter but the noise is in the uV range. The problem when using these voltage regulators is that they burn off all "extra voltage" as heat. So if we have 12 v, reduce to 5 v we have "lost" 7 volts. If you use 1 A, you will "loose" 7 * 1= 7watt (P = U * I). These 7 watt will be converted to heat and it will be very hot in your little box. The voltage reg. vill turn off itself when it gets 125 degrees C. But it will reach that temp quite fast making the charger turn on and off all the time. Plus its not good design relying on fail safe to avoid starting a fire. I suggest you buy/design a "buck converter" which is about 95% efficient. Using only the LM7805 it would be about 41% efficient. Circuit only outputs 10mA (making it useless as a charger, would take 300 hours to charge my phone with this) and is using lots of unnecessary parts. I suggest you remove this instrucable or re-design it.


    Hehe forgot to tell you why it only outputs max 10ma. You have a 470 ohm resistor after the voltage reg. The voltage drop over the resistor is 5 volts (You will have a phone conneced after this resistor acting like another resistor which we further more decrease current). We know the formula U= R*I (voltage = resistance * current). U = 5 V, R = 470. If we solve for I we get 0.01 A. Good luck!


    4 years ago on Introduction

    Nice idea to put everything into a tictac box !

    Why use so many capacitors with a LM7805 ? According to the datasheet, there is no explicit need.

    And also why add a 470ohm resistor on the output ? A USB port can consume up to 0.5A at 5V which means (P=UI) 2.5W which is more than a 1/4W resistor can handle.

    Thank you !

    2 replies

    Reply 4 years ago on Introduction

    The resistor does not need to handle 1/4W since the resistor only will let about 10 mA through, regardless of how much current the usb device can sink.

    Lmecano i just download a circuit from google and built it and fix into a tictac box tell what should i need to replace. I want 2 amp or 1.5 amp what should i do.


    4 years ago

    Could this be connected to the lighter of a car?

    1 reply

    Reply 4 years ago

    This is a good question because my car battery often provides up to 13.5 volts... And the first step states "... input not more than 12 V..."... So I too will hope for a response/clarification. Thanks in advance!