On this problem, I will current you simple strategies to design a simple Robotic automobile that could be managed using a phone. The problem often known as DTMF Managed Robotic with out Microcontroller.


DTMF is an acronym for Twin Tone Modulation Frequency. Robotic automobile based mostly totally on DTMF experience is outlined on this text. Proper right here, is a circuit that operates the robotic with out using a microcontroller. This circuit consists of easy DTMF Tone decoder IC and a motor driver IC.

When a secret’s pressed from our mobile, it generates a tone, which is a combination of two frequencies. Of the two frequencies, one is extreme frequency and one different one is low frequency. This frequency could also be decoded by the decoder IC into binary sequence. Using this binary sequence, the robotic is managed.

DTMF Based Robotic Car Circuit Principle

DTMF primarily based robotic automobile circuit consists of DTMF Decoder IC, Motor Driver IC (L293D or L298N), motors and a simple robotic chassis to hold all these parts.

DTMF decoder IC used is HT9170B (actually a variant known as CM8870 is used nevertheless the efficiency is an identical). It has 18 pins. Tone from DTMF encoder is given to the DTMF decoder IC. The decoder IC internally, consists of operational amplifier, whose output is given to pre filters to separate excessive and low frequencies. Then it is handed to code detector circuit and it decodes the incoming tone into 4bits of binary info. This info on the output is straight given to the driving power IC to drive the two motors. These motors rotate in response to the decoded output.

The subsequent image reveals the binary decoded output much like the vital factor pressed on the keypad.

DTMF Decoded Frequency Output Table

Moreover Be taught the Related Put up: Simple Line Follower Robotic using Microcontroller

If the button pressed from mobile is ‘8’, it supplies a decoded output of ‘1000’ (inside the order of Q1, Q2, Q3 and This autumn). Thus motor linked to the first two pins (OUT1 and OUT2) will rotate and the second motor stays off. So, the robotic strikes in a single path each to left or correct. If the robotic is to rotate forward or backward then the binary price must be each ‘0101’ or ‘1010’. These values level out that two motors rotates within the an identical path i.e. each forward or backward. The above desk supplies the low frequency, extreme frequency and binary output price of each button pressed inside the keypad.

Circuit Diagram of DTMF Managed Robotic with out Microcontroller

DTMF Controlled Robot without Microcontroller Circuit Diagram

Circuit Elements

  • DTMF Decoder IC (HT9170B or CM8870)
  • Motor Driver IC (L293D or L298N)
  • Motors
  • Resistors – 100KΩ x 2, 330KΩ
  • Capacitors – 100nF x 2, 22pF x 2 
  • Crystal – 3.58MHz
  • Robotic Chassis
  • Batteries


  • As talked about earlier, the DTMF Decoder IC used proper right here is CM8870. Nevertheless the circuit diagram mentiones the DTMF Decoder IC as HT9170B. As a result of the pins are related, there acquired’t be any draw back. Nevertheless please examine with the datasheet.
  • Moreover, the circuit diagram mentions the Motor Driver as L293D nevertheless the motor driver used proper right here is L298N. Please refer the datasheet for pin diagram.

DTMF Controlled Robot without Microcontroller Image 1

DTMF Managed Robotic Circuit Design

The precept parts of the circuit are DTMF decoder IC, motor driver IC and motors. The decoder IC used proper right here is CM8870 IC. The second pin of decoder IC is an inverting pin of the operational amplifier.

Tone is utilized to the IC by a sequence of capacitor and resistor. The output of the Op Amp is feed once more by GS pin of the IC. An exterior crystal is linked to the 7th and eightth pins of the IC.

Motor driver IC used is L298N. It has 15 pins. When you’re using a Module, then be part of the Outputs from the decoder IC to IN1, IN2, IN3 and IN4. The motors are linked to OUT1, OUT2, and OUT3, OUT4.

Related Put up: Distant Operated Spy Robotic Circuit

How one can perform DTMF primarily based Robotic Car?

  • Arrange the robotic mechanically i.e. be part of the wheels to the motors, place the circuit on the robotic with a mobile mounted to it.
  • Now press ‘5’ out of your mobile, robotic begins shifting forward.
  • Now press ‘0’ out of your mobile, robotic begins shifting backward.
  • Now press ‘2’ to rotate the robotic in left path.
  • Now press ‘8’ to rotate the robotic in correct path.

DTMF Managed Robotic Car Circuit Features

  • DTMF robotic with slight modifications could be utilized in industrial capabilities.
  • DTMF robotic with human detector sensor could be utilized on the time of disasters like earth quake to detect the human under buildings.
  • DTMF robotic with digicam could be utilized in surveillance strategies.

Limitations of DTMF Managed Robotic Car

  • DTMF robotic couldn’t work accurately whether or not it’s operated with one different mobile when there is not an indication.
  • Mobiles with express jacks are solely used.



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