ULTRASONIC SENSORS

What is Ultrasound?

There are 3 levels of sound:

How they work?

• The sensor keeps transmitting Ultrasonic waves
• When an obstacle comes in between, the waves are reflected and are received by the sensor

How is the distance calculated?

TIME x SPEED OF SOUND

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2

IR SENSORS

The main parts of an IR SENSOR:

• IR LED
• PHOTO DIODE

PROXIMITY

The IR LED keeps transmitting Infrared waves. When an obstacle comes in between, the waves are reflected and are received by the photo diode.

LINE FOLLOWING

The IR rays are transmitted by the IR LEDs and the reflected IR waves are received by the photo diode.

When a white surface comes right below the sensor, the intensity of reflected waves increases and the output voltage of the sensor decreases. When a black surface comes right below the sensor, the intensity of reflected waves decreases and the output voltage of the sensor increases.

INTENSITY OF REFLECTED IR WAVES ∝ _______1

OUTPUT VOLTAGE

COMMUNICATION BETWEEN REMOTE AND RECEIVER

The IR led transmits signals. The PHOTO DIODE receives it

LEDs

WHAT IS AN LED?

A LIGHT EMITTING DIODE [LED] is a semi-conductor light source. It has 2 leads:

• ANODE [POSITIVE] = +
• CATHODE [NEGATIVE] = -

HOW DOES IT WORK?

When a suitable voltage is applied to the leads, the electrons are able to combine with electron holes in the diode and produce light in the form of " ELECTRO LUMINESCENCE "

WHAT IS " ELECTRO LUMINESCENCE " ?

ELECTRO LUMINESCENCE is noting but the light produced using electricity.