Autonomous Line Follower (Simplest IR Module Based)

graphics-click-here-688974Click here to get all components required to build this robot

Today world are very advance in the field of robotics. Still the term robotics it very advance but the hobbyist made it easy as to cope up with their lazy style of working. In this we talk the simplest circuit ever you encounter for the line follower robot.

Components Required:

  • DC geared motor (2 sets)
  • Wheels (2 sets)
  • caster wheel
  • PCB
  • Ribbon wire
  • IR LED (2 sets)
  • Phototransistor (2 sets)
  • 100K-Ohm Variable resistance (2 sets)
  • 330 ohm(3 sets)
  • Power transistor (4 sets)
  • Battery  9V DC
  • Battery connector
  • robotic base
  • Ribbon wire
    To get all the componentsgraphics-click-here-688974 Click here.

Design & Working:



for the design the first part is the sensor module and for that we use the  infrared module, first we take an IR LED and get it glow via a 330 Ohm resistance on the 9 Volt grid as shown in figure-1 (Always keep in mind that the Positive lead having longer terminal of IR LED), then comes our sensor part for that we’ll use a Phototransistor that is a very good sensor having immunity to the visible range light and hence very good for indoor robotic event as if will not malfunction due to the environmental lights which is present in the case of LDR based circuits. As far as the Phototransistor is concern always keep in mind that the longer terminal is emitter and shorter terminal is collector so when it connected to the circuit as per the  design is looks like you connected oppositely as we normally see in case of LED that we always connect the small terminal to the ground. but remember the Phototransistor is not the LED so instead it looks like we are connecting in opposite way as LED but the connection is correct. then we connect the variable resistance from the collector and the positive bus of 9 Volt grid (Use of variable resistance instead of fixed resistance has its own advantage as we can always has a facility to tune and adjust our sensor as per the requirement by just varying the variable resistance). there after we connect he middle point of PT(Phototransistor ) and variable resistance to the base of another NPN Power transistor which having a 330 Ohm resistance on its collector terminal having its other terminal to the positive but of the 9Volt grid. then the final connection is made via the collector terminal of 1st Power transistor is being connected to the base of second stage power transistor  which having a motor to its collector terminal. Yeah!!! it’s a quite good question why we are using two transistor, is it possible to use a single transistor instead? the answer is yeah, but in that case the tuning of the variable resistance should be precise and any deviation in the environmental IR light required another tuning, So to increase the circuit performance we like to employed 2 instead of one. Moreover it can work Black Line follower and White line follower both we have to just swap the position of PT and variable resistance or can put the sensor inside and outside the track.

Ohhhh….. The actual design has some more adventure then we see here in the circuit since we have to put the sensor module at the track level so make a sensor module by taking the circuit component out of main circuit as the shaded part shown in Figure-2 into the path sensor module and the terminal connected back to the circuit via a hard wire.

Now here are few tips over the mechanical arrangement of the setup. for the optimal dynamics control of the Robot always keep your sensor module in the direction of the motion at the half of the distance between wheels  in front of the wheels axis. So here is we are finally now take your Robot and do some artwork on it….. :) :):):)

Audio Amplifier

Now a days We all Are using Amplifier as part of TV , Home Theater and many more so i thought why we will not made an amplifier By Himself. this circuit can be used with a small 9 volt Battery Operated,Current use as little as 5 milliamps.And amplification up to 500 mW.

This circuit number LM386 IC is used as the IC, which is popular is that it has. It is a simple circuit. Less equipment items. Suitable for use or used in small trials.
The properties of the IC can be used from 4V-12V power supply for low current at 50 mA only. And the frequency response from 40Hz – 100 kHz rate of expansion of 46 dB and distortion. Less than 1%.


  • LM386
  • an Speaker
  • 10 UF ,220 UF and 0.1UF capasitor
  • 10 K ohm Resitance
  • Battery ( 9 volt)

Here The Circuit Diagram Is Provided


Heart Rate Monitoring Sensor Circuit

Heart rate is a very vital health parameter that is directly related to the soundness of the human cardiovascular system. This project describes a technique of measuring the heart rate through a fingertip using a PIC microcontroller. While the heart is beating, it is actually pumping blood throughout the body, and that makes the blood volume inside the finger artery to change too. This fluctuation of blood can be detected through an optical sensing mechanism placed around the fingertip. The signal can be amplified further for the microcontroller to count the rate of fluctuation, which is actually the heart rate.

Reflective And Transmissive Pulse Oximetry

Pulse oximetry is a noninvasive photo-based technique that measures the light absorption and refection properties of deoxygenated and oxygenated hemoglobin. The amount of light absorbed in the hemoglobin is defined by the Lambert-Beer Law, which associates the degree of light absorption with the wavelength of the beam light, the path length, and the absorption coefficient of the blood constituents.



  • IC LM358
  • Potentiometer (2×100 K ohm).
  • Resistance (1×220 Ohm, 1×10 K,1×1 K, 1×47 K, 1×100 K.
  • Capacitor (1×100 nf , 1x 479 nf).
  • IR LED
  • IR Receiver.
  • Microcontroller board.
  • Display (LCD , LED Or Seven Segment).
  • Power Supply.

Sensor Assembly

The sensor unit consists of an infrared light-emitting-diode (IR LED) and a photo diode, placed side by side, and the fingertip is placed over the sensor assembly, as shown below. The IR LED transmits an infrared light into the fingertip, a part of which is reflected back from the blood inside the finger arteries. The photo diode senses the portion of the light that is reflected back. The intensity of reflected light depends upon the blood volume inside the fingertip. So, every time the heart beats the amount of reflected infrared light changes, which can be detected by the photo diode. With a high gain amplifier, this little alteration in the amplitude of the reflected light can be converted into a pulse.


Automatic water tank Filling System

Automatic water level controller circuit is a simple project. It can automatically switch ON and OFF the domestic water pump set depending on the tank water level. You can implement this motor driver circuit at your home or college using less costly components.  The main advantage of this water level controller circuit is that it automatically controls the water pump without any user interaction.
The heart of this pump controller circuit is a NE 555 IC; Here we have manipulated the flip flop inside the 555 timer IC. Our project consists of two water level sensors, one fixed at the top and other at the bottom. Working of this circuit is almost similar to a bi stable mutlivibrator.

  • By Using This Project you are able to save water
  • By Using this you are able save time on monitoring to tank full and  to close Motor.
  • By using you are making you home to Smart Home category


  1. Power supply (6v)
  2. NE 555 timer IC
  3. Resistors (100Ωx2, 10kΩ)
  4. Relay (6V, 30A)
  5. BC 548 transistor x2
  6. 1N4007 Diode

Automatic Water Tank Controller Engineering Project