Ohm's Law

Ohms law states that the current flowing through a conductor is directly proportional to its potential difference provided that physical conditions (temperature) remains constant.

Mathematically,

I α V

V = IR

Where,

V = potential difference measured in volt
I = current measured in ampere
R = constant (resistance) measured in ohm

This law established the relationship between voltage, current and resistance.

When the voltage is kept constant, the current flowing in a circuit will increase with decrease in resistance and the current will decrease with an increase in resistance.
Also, when the resistance is kept constant, the current will increase with an increase in voltage and will decrease with a reduction in voltage.

ROBOTICS BASICS

The word robot was coined from the word ROBOTA which means "forced labour".

Robot is an electromechanical machine embedded with artificial intelligence (AI) which is reprogrammed and executes various tasks. It is a universal machine hence, the re-programmable ability. 

Robotics technology deals with the research, design, building and controlling of robot.

All robots are machines but not all machines are robot.

Not all software's are artificial intelligence (AI). Artificial intelligence replicates human actions. If a software's does not meet this, it is not AI.

STRUCTURES OF ROBOT

• Control unit
• Mechanical unit
• Programming unit

Control Unit: This section is made up of sensors that provide feedback from the physical world to the digital world which are processed for action to be taken based on the information stored in the memory of a control computer., 

Mechanical Unit: This section of a robot is comprised of motors (stepper, servo) which provides locomotion, bearings to provide support, joints to provide a degree of freedom, end-effectors to interact with the environment and carry out assigned tasks depending on design.

Programming Unit: The control unit of a robot need to be programmed (storing of processed datain its memory). This is done in the section.

APPLICATION AREAS OF ROBOT

- Bomb discarding in the military

- Material handling
- Mechanical cutting
- Welding (Arc welding, spot welding)
- Painting in automotive industry
- Domestic use (pool cleaners, vacuum cleaners)
- Exploration

HOW TO READ RESISTOR COLOUR CODE

Resistor colour coding is used to represent the value and tolerance of a resistor. This colour coding could be four, five or sometimes six.

In a four band colour coding, the first two colours represents the first and second digits, the third colour serves as the multiplier and the last colour is the tolerance.

To find the resistance of a resistor whose colours are Orange, Orange, Brown and Gold.

VARIABLE RESISTOR

A variable resistor has a movable contact that is used in selecting the required resistance. Potentiometers have markings on them; these markings indicates the maximum value in which the potentiometer can be adjusted to.

Recognising markings on variable resistors:

A variable resistor marked 10K means that its range of resistance is 0 to 10,000 ohms.
If it is marked 104, the resistance will be 10 x10^4 = 100,000 ohms.
If it is marked 103, the resistance will be 10 x10^3 = 10,000 ohms.

Variable resistors are of either the slide type or the rotary(dial) type.

DIODE

A diode is a semi-conductor that allows current to flow in one direction from anode to cathode and blocks the opposite direction. Diodes are polarised; the positive terminal is the anode and the negative terminal is the cathode.

Looking at a diode, the coloured band at one of the terminal is the negative terminal (cathode).

555 Timer - Astable mode

Astable operation is a free running oscillator without any stable state. The threshold terminal (pin 6) and the trigger terminal (pin 2) are connected together to form a self-trigger. This ensures that an external trigger is not required for its operation.

The pulsewidth is determined by two external resistors and one capacitors using the constant 0.693(R1 + 2R2)C1

555 Timer - Monostable mode

Monostable operation have one stable state and an unstable state. By default, the circuit rests in its stable state but it can be switched over into its alternate state whenever there is an external trigger on its trigger terminal(pin 2) where it will stay for a period of time before moving to its default state. The trigger voltage must be below one-third of the supply voltage(VCC/3). 

RF transmitter and Receiver circuit

  Whenever there is an input from the push button, it is received by the encoder (HT12E) as parallel data. It is converted to a serial data and sent to the transmitter. This data is modulated by the transmitter and sent at a frequency of 433MHz. The transmitted signal is picked up by the receiver at the same frequency as that of the transmitter and demodulated before being transferred to the decoder (HT12D). HT12D compares the serial input data three times continuously with the local addresses.

If no error or unmatched codes are found, the input data codes are decoded and then transferred to the

Light Activated Switch Using LDR and Motor

The DC motor in this circuit serves as the output which is switched off or switched on by the presence or absence of light on the surface of the light dependent resistor (LDR).

Thermistor

A thermistor is a type of resistor whose resistance changes rapidly with temperature. The word 'thermistor' is derived from "thermal" and "resistor". They are temperature sensors.

Picture of a thermistor

Thermistor symbol

Light Dependent Resistor

What is LDR

Light dependent resistor is also referred to as photo-resistor, cadmium sulfide (cds) cell, photoconductor or photocell. It is an electronic component whose resistance changes with the light intensity falling on it. It has the ability to detect the presence or absence of light and this detection reflects on its resistance value.This allows them to be used in light sensing circuits. Their ability to produce a very large change in

Resistor

Resistor Basics

Resistor is an electronics component that offers opposition to the flow of electrons. This resistance have a specific electrical resistance. Resistors are primarily used for current limiting, voltage division and similar functions.

The resistance of a resistor is measured in ohms using the Greek symbol omega (Ω).

Picture of a resistor