Circuit to Control two DC Motors using Mobile Phone through MT8870DE DTMF

<<<< Previous : Control Four LEDs using Keypad of a Mobile Phone through Audio Jack

We had already seen the circuit to control four LEDs using the keypad of a phone in my previous blog. Here, we will make some modifications in the circuit to control the direction of rotation of two DC motors using a mobile phone which is connected to the audio jack in the circuit. Same circuit can also be used to control the same motors from anywhere using another mobile phone. Circuit is done as shown in the following diagram.

Before doing the circuit, you must read my previous blogs on,

4000-4000-another-copy (6th copy)


After completing the circuit, connect a mobile phone to the audio jack and dial numbers. If no responses are getting, change your phone. It’s better to use an old model phone for this purpose. If everything is fine, binary coded decimal corresponding to each keys will be displayed in the LEDs. Same motors can also be controlled from anywhere using a second phone. Do the following steps to control the direction of two DC motors from anywhere through your mobile phone.

  • Take two mobile phones and connect first phone to MT8870D through an audio jack.
  • Take second mobile phone and call to the phone connected to MT8870D (first mobile phone) from second mobile phone.
  • When the phone connected to MT8870D (first mobile phone) rings, accept call.
  • Now, call will be in progress between first and second mobile phones. Take the keypad in first mobile phone and press numbers. If ‘1’ is pressed, one motor will rotate in a direction. If ‘2’ is pressed, that motor will rotate in opposite direction. If ‘3’ is pressed, motor will stop rotation. Press ‘4’ and ‘8’ for rotating the other motor.

Key pressedQ4Q3Q2Q1Result
10001Motor 2 will rotate in one direction
20010Motor 2 will rotate in opposite direction
40100Motor 1 will rotate in one direction
81000Motor 1 will rotate in opposite direction
60110Both motors will rotate in one direction
91001Both motors will rotate in opposite direction
30011Both motors will stop rotation

Watch the video demonstration here.

Next : Identify the Pressed Keys of a Mobile Phone using Arduino through MT8870DE >>>>

(Visited 3,073 times, 1 visits today)
A deep electronic enthusiast who spent most of my time for electronic experiments. I am also interested in publishing my experiments in my blog for helping other electronics enthusiasts.