What is Switch?

A switch is an electrical component that can connect or disconnect a current flow path. In other words, switches are the gadgets that allow us to control the flow of current. For example, we have lights, fans, and a variety of electrical equipment in our home. To turn on the devices, we turn the switch on, and the electrical current is established. To turn off the devices, we flip the switch that disconnects the present flow channel.

Types of Switches:

Mechanical Switches: - This sort of switch operated either manual contact or mechanical pressure. In general, we use it to control home appliances that require a manual interaction. Mechanical switches are classified into numerous varieties based on the number of input (Poles) and output (throw) contacts.

Electrical Switches: - Electrical switches are commonly composed of semiconductor materials and are controlled by a little amount of electric current. Normally, the current flow in digital circuits can be controlled by electrical switches based on the biasing voltage. Transistors, diodes, and MOSFETs are examples of electrical switches. In this tutorial, we will focus on mechanical switches and their various types. We shall explore this sort of switch in detail under the semiconductor devices topic.

Types of Mechanical Switches: -

  • SPST – Single Pole single Throw
  • SPDT- Single Pole double Throw
  • DPST- Double Pole Single Throw
  • DPDT- Double Pole Double Throw

Single Pole single Throw

As we know, pole denotes the input and throw denotes the output. In this case, single pole single throw means that the switch can only control one device based on a single input voltage.


Single Pole double Throw

A single pole double throw switch has three terminals, one of which is common to the other two. The common terminal is known as INPUT, while the other two terminals are known as output. Based on a single input delivered to a common terminal, this switch is capable of controlling two loads in a circuit.

 

Double Pole Single Throw

Double pole single throw switches have two inputs and two outputs that can be controlled independently by a single toggle. This switch's characteristic allows it to control two discrete circuits in a single toggle. That is, we can provide independent input to the terminals and control two separate outputs with a single switch click. The single switch in the diagram below is used to control the two separate circuits.                                               

Double Pole Double Throw

 The six terminal switch functions similarly to two distinct SPDT switches, allowing it to control two discrete circuits and two loads in a single circuit. As previously discussed, SPDT may control two outputs in the same circuit using a single input. In this case, the DPDT switch controls two separate circuits and two loads in each circuit. This switch can be used as a simple wired remote to navigate the robot in robot applications.


Activity: - 4 – Simple Switching Circuit  

            To learn the working and connection procedures of switches, we will design a simple circuit in Tinkercad with the switch to control the led on/off operation.

Components Required: -

1.      Battery 9V - 1

2.      LED - 1

3.      Resistor 470 Ohm – 1

4.      Slide Switch

Connection Procedure

  1. Using the above list, choose and place the appropriate components in the circuit area.
  2. Arrange the components in your circuit area as shown below.
  3. Connect the wire from the positive terminal of the battery to the common terminal of the sliding switch.
  4. Next, connect the wire from slide switch terminal 1 or 2 to resistor terminal 1.
  5. Connect the other end of the resistor to the led's anode and cathode to the battery's negative line.
  6. Once we've completed all of the connections, run the simulation while keeping your cursor on the slide switch to toggle it.
  7. The LED is turned on when the sliding switch knob is positioned between the common and linked terminals. If it is on the opposite side, the LED remains turned off.
  8. As previously said, the switches may connect or detach the electrical current, therefore we can attach it to either the positive or negative line of the connection.

Circuit Diagram: -

Switch in Positive line.


Switch in Negative line



Activity: - 5 – Single Pole Double Throw Switch  

            As previously said, the SPDT switch can control two loads in a single circuit; thus, we will use a Tinkercad slide switch to link two loads in a single circuit in order to learn how the SPDT switch works.

Components Required: -

1.      Battery 9V - 1

2.      LED - 2

3.      Resistor 470 Ohm – 2

4.      Slide Switch

Connection Procedure

  1. Using the above list, choose and place the appropriate components in the circuit area.
  2. Arrange the components in your circuit area as shown below.
  3. Connect the positive wire from the batteries to the resistor terminal one and the other end of the resistor to the slide switch common terminal.
  4. Now that we have two leds in our circuit region, connect the wire from the switch terminal to the first led anode.
  5. Connect terminal 2 to the second led anode and both led cathodes to the battery's negative terminal.
  6. Once we've completed all of the connections, we can run the simulation to see how it turns out.
  7. Now observe that the relevant led is turned ON and the second led is turned OFF based on the position of the knob of the slide switch. By adjusting the slide switch position, the second led turns on and the first turns off.

Circuit Diagram: -