Cellphone Operated Robot

Description:
It is basically a robotic car which can be controlled using mobile phone.The key component in this robot is DTMF decoder ic.It takes the dualtone frequency as input and produces output in binary form.In cellphones when we press any key we will listen different tones.That tone is a linear combinations of two sinosoids of different frequencies.Here is the table.

The dtmf decoder takes these frequencies and gives binary outputs.We will give the input tone to dtmf decoder using audio jack from phone 1. We call this number using phone 2 and press buttons,the tons will go to decoder through adio jack and the ic will produce different binary outputs for different key pressed.These binary output can be used to control the robot using microcontroller.
Circuit:

The tip is connected to the tip of the adio jack.ring is connected to the bottom ring of the adio jack.

The two other end points in right side of dtmf circuits  are connected to the 9v battery.The output will be taken from Q1 to Q4.The output buffers are not necessary.

Connect the other end of the jack to audio pin of the phone.Keep the phone in automatic answer mode.Call this number from other phone.As u press the keys the output starts coming.Put LED's to test.When u press 1 in mobile Q1=9volts,Q2=Q3=Q4=0.Similarly when u press 2, Q2 becomes high and so on.These outputs are taken and given to 8051 micro-controller.The output of the microcontroller is given to the H-bridge ic to control the motor rotation of the robot.
So we can control this robot almost anywhere in the world,if u can establish call from a mobile to the cellphone in the robot! The area of operation is same as the area of the service provider.
Not only this robot we can trigger any circuit by using this amazing ic.
You can see the final product video at this link

Team members:
Dheeraj kumar c
Kumar bharat
Darshan ramakant



Have fun..