i want to build a quadcopter from scratch. and i have a very low budget...nt more than 10k(even less preferable).
so i wanted to know of any way that i can use my android phone as transmitter and any receiver.
i really want to cut down on cost and i think if i can somehow utilise this idea,i can maybe achieve my goal.
any help will be appreciated

im new to all this. this is the very first time that i am trying to build something like a quadcopter.
i just wanna say that i read some articles and found that esc and txrx are two different things. u gave me info about esc,but i really want to know about tx and rx part.

Okay we will start from components. How a quadcopter works. We have 4 motors. Every motor is connected to an ESC (Electronic Speed Controller) which is a device that takes PWM (Pulse Width Modulation) Signals from the flight controller in case of quadcopter and from the receiver in case of a plane. The signals generally ranges from 900 to 2000 baud, 900 is lowest and 2000 is highest. So if it receives 900 baud signal then it will shut the motor down, if the signal goes 1000, it will increase the speed of motor accordingly by taking appropriate amount of current. When the signal is 2000, the motor will be at its full speed.
   Motors used in RC are brushless DC motors and ESCs are devided by max Amps of current it can provide. Now in case of a quadcopter, we always need a flight controller which is nothing but a simple micro-controller that does some processing and sends data to ESCs to control the speed of each motor. Each ESCs are connected to flight controller. KK 2.1 is very beginner flight controller, with CC3D, Naza M lite, Multiwii are intermediate where Pixhawk and Naza M are some examples of high end flight controllers.
    Now theres another system lies between this is radio system. Which is tx/rx you are saying stand for Transmitter and receiver. A transmitter is a thing containing two 2-axis gimbal sticks to control throttle, roll, pitch and yaw of aircraft. It transmits radio signals at 2.4 GHz frequency in most of radio systems, and also a receiver which listens on same channels. To fly any quadcopter we need at least 4 channels. Flysky FS-i6 can be good beginner radio. The transmitter takes inputs of throttle, roll, pitch, yaw from the sticks and transmits that signal. The receiver catches that signals and send that signals by converting it in PWM signals to the flight controller. (Some advance radios and flight controllers support PPM signals that is Pulse Position Modulation which can handle multiple channels at single bus.) Then flight controller stabilizes with the help of some sensors like gyroscope or compass and many other. And also it do the calculations how much the speed of the appropriate motors should be increased to do roll/pitch/yaw as per user demand. This is how it works.

Now getting to the point about controlling the quad with your android phone. Android phones don't transmit such signals and there is no receiver. There's another a possibility to achieve it with the 3DR telemetry that we can connect to android tablet to see current telemetry data transmitted by Pixhawk flight controller about current statistics. Now you have the hardware, which can transmit and receive signals. Now the software part. You have to make an app that will communicate with that telemetry ground station to transmit control signal with the help of user input whatever you will assign  gyroscope in mobile or whatever. But honestly controlling quadcopter from any mobile phone will be very difficult. Controlling a car from any android phone can be easy because it only moves in 2 Dimension but here it flies, it moves in 3 Dimension so it will be very difficult. Another method you can do is to send signals through wifi and program arduino to receive the signals through wifi and send PWM signals to Flight controllers. In both cases you need to make an app that will create hotspot and will send signals to other devices in wifi via an opened port, just like torrent works, just you have to transmit signal data instead of packets in torrents and then receive with arduino and then send PWM signals to flight controller.
Hope this helps.

that is very detailed and i appreciate it a lot, but could you please tell me which board i can use and motors too?

You would need a wifi receiver and a app which sends signal to that wifi receiver. and thats how you would control the aircraft using android.

Since u wanna cut the cost of radio... U can di something's else

Buy fsi6 for 2.9k from RC Mumbai
Make an wooden frame.. Search through the forum u ll get to know how to do that
I had put a link above.. Check that...
But buy good motors dn go for cheaper ones...
U can get Kk for 1.5k
Battery and charger for 1.6
 So totally that may come 11k


So 2.9+2+3.2+1.5

Controlling by phone is not a good idea. There are several toy quads that are controlled by phone (using wifi) and they are laggy as hell.

First learn to fly a quad normally, then you will understand how difficult it is to control a quad by non conventional methods.

Inv3ntor bro !!! u got too serious !!! :p just kidding anyways nice info for a beginner. As inv3ntor said ,  u can use the 3dr telemetry module to control the quad.
have a look here http://aeroquad.com/showthread.php?3898-Quadcopter-telemetry-and-control-with-an-android-phone

thanks so much guys. and just to clear things please tell me if the KK v5.5 or any version would be sufficient for my quadcopter. i will be using those 7mm coreless motors which i believe doesnt require individual esc. but the board has to be brushed kind or something. if someone could clarify this for me. it will be of great help.
here is a pic of the motor for refernce:

Hi abhinavbhopal26,
As Mr Cycloned said,its really not a good idea to fly using your smartphone,that too for 1st time!!!,i don't think u'll  be able to enjoy flying with your phone rather than a tx.
From my experience building a normal quad itself is little tricky for the 1st time.Building a quad ,that can be controlled with phone using wifi or some other techniqes needs a bit experience in app developing,& also experience with arudino(or any other development board) projects,so i would really recommend u to buy some cheap toy quads and learn flying & then u'll gain confidence in flying a normal brushless quad,i don't recommend u to learn a very basic flying(1st time flying) form the quad u build,because u'll crash it lot of times  and end up paying for its repairs & moreover u'll NOT  BE ABLE TO JUDGE IF YOUR QUAD IS REACTING PROPERLY FOR YOUR CORRESPONDING CONTROLE'S(stick movement),BECAUSE U HAVE NEVER FLOWN IT BEFORE.

you cannot connect brushed moter's directly to Fc(Flight controller) like kk,naze 32,ccd3,etc.
Their are Fc specially made for brushed moters which has built in esc and somtimes reciver too( in link below)

http://www.aliexpress.com/item/Micro-Scisky-32-Bits-Brushed-Flight-Control-Board/32620766447.html?spm=2114.01010208.3.179.KgZl1y&ws_ab_test=searchweb201556_0,searchweb201602_5_10057_10056_10055_10049_10017_405_404_10059_10058_10040_10060_412,searchweb201603_2&btsid=6d2ac6de-5000-49d5-af9f-7c9f4dae5016

in the above link fc has in built dsm2 reciver, but tx with dsm protocol  like spektum etc are costly
                                  or
http://www.aliexpress.com/item/SP-RACING-F3-EVO-Brush-Flight-Control-Board-For-90mm-120mm-125-mm-FPV-Mini-Micro/32701619346.html?spm=2114.01010208.3.19.jtQR0X&ws_ab_test=searchweb201556_0,searchweb201602_5_10057_10056_10055_10049_10059_10058_10017_405_404_10040_10060_10061_412,searchweb201603_2&btsid=2e6fc276-f53f-4df3-b617-e568aa0408cc

in above link fc has no inbuilt rx ,so u need to use a micro reciver like
http://www.banggood.com/FLYSKY-Ultra-Miniature-PPM-Signal-Output-8CH-Receiver-For-Multicopter-p-988175.html
which is AFHDS type,i foud that people were able to bind other AFHDS receivers with flyskys i6,so it should be  compatible with flysky i6(but i'm not sure about it ),flyskys i6 available for cheap best prize in rcmumbai .

but i guess most of the stuff in link are not available in india,many people don't advice importing stuff for the 1st build,but u can give it a go,more over brushed moters don't last long , they last for 7 to 8 hrs.

since u r on a budget plane ,do have look at cheapass quad(check in youtube)
when i was to build my 1st quad ,i had a plan of this cheapass quad,then i found its not  advisable for a beginner,so i build a 250 brushless quad,but i was unable to fly because of pid tuneing,so i stopped their & bought a toy quad to learn flying ,then with great difficulty tuned pid ,after i got familier to flying, enjoyed a lot.

so trust me bro,my personal advice is buy a cheap toy quad ,then wait for 11 or 12k budget in ur hand ,then build cheap brushless quad as Mr Devanesan Andrews said

rc experts ,i'm a beginner too ,so please do correct me if i'm wrong.