Introduction: Emergency Mobile Charger Using DC Motor


This is a hobby project which can be made by anyone following some very simple instructions. The charger works on the principal of DC motor being used as a generator converting mechanical energy to electrical energy. But since the voltage required by a phone is 5V a voltage regulator IC 7805 is used to get the desired output voltage from the DC motor.

For more information, click here

Step 1: Items Required

Picture of Items Required

1. DC motor 12V – 60RPM: Geared motor most suitable for this project. (Available here:

2. Voltage regulator IC 7805: This will give you constant output voltage, doesn't matter what the input voltage is. (Available here:

3. Male – female USB cable: The female end is required to connect the USB cable of the phone to the generator. (Available here:

4. Glue Gun (Available here:

NOTE: Those are affiliate links.

Step 2: How It Works?

Picture of How It Works?

When the shaft of the DC motor is rotated a DC voltage is induced at the terminals. But since its not possible for a human being to maintain a constant RPM of the shaft the output voltage of the motor keep varying at some time going beyond 5V which is above the save limit of the phones. Thus an IC 7805 is used to regulate the voltage and to make sure that we have a constant 5V.

The following are the steps to be followed:

1. Cut out the female end of the USB cable and clip of the data cables. (We require only RED and BLACK wires)

2. Now using a solder iron make the following connections as given below :

3. Paste the IC 7805 and female USB port on the surface of the motor using a glue gun so as to secure it on the surface.
4. Use a right angled iron rod at the shaft as handle for the ease of rotation.

5. Bingo! now you are ready to test your ‘Emergency Mobile Charger’

Step 3: Detailed Video

Picture of Detailed Video

For more information watch the video.


Ashishb51 (author)2017-08-25

I prepared 1 project to charge smartphone via bicycle dynamo, i used DC motor, IC7805, Capacitor & charging cable, I connected them in parallel & when I'm checking the output voltage in multimeter, it shows 5V & current more than 200mA, & when i connect my smartphone, it shows connected & within second it shows disconnected, & unable to charge my phone,
so like to know where I'm doing wrong,
kindly suggest,
Thanks in advance,

16me121lucifer (author)2017-02-08

A great idea to work with!! Can this motor be used to make a mobile charger running on wind energy?

Laibaig (author)16me121lucifer2017-02-08

That's a very innovative idea !
Yes it can be, provided the RPM of the motor is high enough such that the output voltage is greater than 5V so that the IC 7805 can give a stable output.

Please do share when you make it ! :D

Bolmik (author)Laibaig2017-08-20

Will it work for an hour or so??????

16me121lucifer (author)Laibaig2017-02-08

So have i to use the motor with rpm>60? Or the motor which you have used will work? ie. for vehicle having speed around 50-60km/hr.
Also how much current is produced by the motor used by you?

Laibaig (author)16me121lucifer2017-02-08

What I meant was that the RPM of the motor when exposed to wind (Let's say while in a moving car) should be high enough so that the output voltage of the DC motor is greater than 5V.

The maximum output current as per the data sheet of IC7805 is 1.5A

Bolmik (author)2017-07-20

Will it work for an hour

Bolmik (author)2017-07-13

How long does it work ?

ShreelC (author)2017-02-03

Wont work long, the motor will die soon and the back EMF of motor won't be safe!

Amit_Jain (author)ShreelC2017-02-03

can you share more details, I want to understand...

Laibaig (author)ShreelC2017-02-04

Thank you for your feedback much appreciated. Please note the project was tried and tested. But yes in order to protect the charging mechanism against back EMF a diode can be installed to the input of IC 7805. Hope that helps :)

BharainiD (author)Laibaig2017-02-06

Can you show how that will be with the diode

Laibaig made it! (author)BharainiD2017-02-06

Please find the circuit diargram attached. I hope this will be usleful.

ShreelC (author)Laibaig2017-02-04

Back EMF generated by motors would damage motor as well and would kill the internals of motor over the time.

BharainiD (author)2017-02-21

Can you give the diode specification to be used to prevent back emf

BharainiD (author)2017-02-06

Does this work

Laibaig (author)BharainiD2017-02-06

Yup it does, why don't you follow the steps I have mentioned and try yourself. If you face any difficulty feel free to contact me :)

ahmet_024102 (author)2017-02-04

thank you. but its can be dangerous because not safety. why battery will take not good amper. because generator changin mA everytime. this is just important time means no places elecktric ok you can use this. but normal time dont do like this. important good energhy

Laibaig (author)ahmet_0241022017-02-05

Thank you for your feedback :)

Sainath tate (author)2017-02-04

Great video

Laibaig (author)Sainath tate2017-02-05

Thank you so much :)

I'm glad you liked it, have a beautiful day.

sumondigi (author)2017-02-04

what a good analogue idea. thanks for sharing.

Laibaig (author)sumondigi2017-02-04

Thanks alot !

Have a nice day !

About This Instructable




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