Push button switches are some of the most commonly used switches that are used in both offices and homes throughout the world. Modern push-button switches are made of metal and plastic and come in different designs and shapes for both latching and momentary actions for electric appliances and many more. While it may seem simple, push-button switches are essential for breaking and connecting electronic circuits. Here is a guide on the push button switches that you may come across or use in your daily life.
What Is A Push Button Switch?
Push button switches or push switches are small lever-like devices used to create or break an electronic circuit. It is also used to control actions in machines that ruin electronics. In simple words, push button switches are used to run or stop electrical appliances or circuits.
How Does A Push Button Switch Work?
When you press the button or actuator, it applies pressure to the internal spring. The depression of the spring then makes the switch fixed to its stake position, located at the bottom of the button. This pressure, in turn, closes or opens the electric circuit connected to the switch. When you again repeat the action, the spring retracts, and the switch reaches another stable position.
When the electric circuit is open, there is now electricity flow. Hence, the connected electric equipment stops working, and the machine or mechanism turns off. On the contrary, when the button is pressed to close the electric circuit, it closes the circuit, causing electricity to flow through it. Hence, the device connected to the switch starts operating through the electricity.
There is also a type of push button with a retractable spring that causes the switch to return to its open position when the switch is not pressed.
What Are The Different Types Of Push Button Switches?
1. Based On Shape
a. Square
Square switches have a square shape or rectangular-shaped buttons. Usually, single-pole, single-throw switches are found in this variant. But most modern push switches come with rectangular or square buttons.
b. Round
The round push switch buttons are usually round or spherical in shape.
2. Based On Performance/Working
a. Single Pole, Single Throw
The single pole single throw switch or SPST switch is a push button switch used to disconnect or reconnect a single conductor in a single branch circuit. Such switches usually come with two terminals. It is mainly used to manage the power supply of an electronic circuit. Besides that, it is also used as a regular on-offs witch. Such switches usually remain in their “off” position, and when pressed, it gets to the on position. When released, the SPST switch returns to its off position.
Single pole single throw switches are a combination of two terminals- Common or C and Normally Open or NO. Hence the switch plates are connected and current flows through the circuit.
The current passes from the C or common terminal to the NO terminal when pressed. If you turn the switch off, its circuit gets opened, and no electricity flows through it.
The switches that are used to operate the lights in places are usually Single pole Single throw switches. The best part about such switches is their simple design with less cabling and low cost. On top of that, these switches can efficiently work with high voltage and currents without causing much trouble.
But, SPST switches are not very durable and often require replacements.
b. Single Pole Double Throw
Single pole double throw or SPDT switches connect or disconnect the single conductor with one of the two present single conductions. Such switches have three terminals and can be used as a “three-way switch.” That means SPDT switches can be in on or off positions and can be used to turn on two devices with different push actions.
The SPDT switches can be handled manually or automatically using an electromagnetic coil. This output terminal usually relays to the AC terminal. The moment the switch is in its off position, the two terminals connect, which breaks the circuit, and electricity flows through it. When you turn it on, the terminals are disconnected, and the current flow stops.
Let’s have an example to understand the mechanism. An SPDT switch can turn on a blue light in one position and a different red light in its second position. There are also special Single pole double throw switches that come with a third switch position, allowing disconnecting both present single circuits.
c. Normally Open
The Push to make or “Normally Open” or ON switch is a switch that activates an electric circuit. When you first press the button, the spring causes the circuit to open and the electricity flows through it. Then again, when you repress the button, the spring returns to its original position, and the electronic circuit is broken. Doorbell switches, calculators, or keyboards are Normally Open switches.
d. Normally Closed
The other switch is the “Normally Close” or NC switch. When you push the NC switch, the present is pressed, which breaks the electric circuit. When it is pushed back, the circuit is opened again.
For example, the forge light switch and the alarm switches are all NC-type push switches. If you closely observe the fridge light switch, it usually remains in the off position. The switch is pressed whenever you open the fridge, and it turns on the lights inside. When you again close the fridge, the lights automatically turn off.
e. Double Pole, Single Throw
The double pole single throw or SPST switches come with four terminals. It is a type of push switch that connects two different circuit conductors in a single circuit but not with each other. Here the term Pole indicates the number of circuits that the switch can control, and the “Throw” indicates the extreme position of the actuator. Usually, the switches work together and can be used with the “ON/OFF” configuration, i.e., two terminals for the “ON” position and the other two for the “OFF” position.
In other words, you can consider a Double pole single throw switch as a combination of two single pole single throw switches in tandem mode. With SPST switches, you can keep the two circuits separate and isolated from each other and even use different voltages for each circuit. If multiple voltages are used, the SPST switch comes with two inputs that go to two different outputs in the circuit.
With SPST switches, you can close or open two different circuits and use each independently. On top of that, it also offers simultaneous functions of two different terminal parts.
f. Double Pole, Double Throw
Double pole double throw switches or DPDT switches connect two conductors with two different circuits. Such switches come with six terminals, including two independent input and four output terminals. The output terminals are separate. At present, DPDT switches are the most advanced designs.
Each input terminal is linked to four output terminals. The switches separate those two conductors with two unique circuits. The double pole regulates the two circuits, and the Double throw closes the circuit with up or down positions. Such switches usually come with ON-OFF-ON or ON-ON settings. Its first variant will have Up and Down positions, while; the second will have three positions, up, down, and hold.
g. Break Before Make
The Break before making switch is a switch that opens the circuits and then closes the new circuits. Hence, it creates two different paths for the old and new signal paths and closes the memory shortage between the two different signal paths.
It is a type of Single pole Double throw switch. BB switches are commonly used to pass electricity at a high rate. When the transfer switch rates the second path without closing the first connection, there is no power to the downstream load.
It is mainly connected with a closed throw circuit and disconnected from the open throw circuit. When turned on, the switch gets disconnected from the closed circuit first and then connects to the open circuit. The two multiplexed pathways must be separated to ensure no signal distortion if the switch is used for multiplexed applications. Most analog switches are BBM switches.
h. Make Before Break
Make-before-break switches create new signal paths before breaking or closing off the previous path. That means the center contact remains connected with both signal paths momentarily. In simple words, it is used for high-voltage electric appliances. This type of switch usually switches the electric load to a first power source and then to the second power source to establish the second connection before closing the first connection.
The pole of the switch is connected to the NC throws circuit and is disconnected from the NO circuit. When operated with a switch, it connects the NO circuit and then disconnects itself from the NC circuit. In the meantime, the switch works so that the two different plants are not electrically disconnected.
i. Momentary Switches
Momentary switches are the switches that need constant pressing to work. Such a switch will remain in one position if you apply pressure on them. The switches instantly return to their original positions when the pressure is released. For example, the buzzer bell, the hand or foot control switches of hospital beds, etc.
j. Latching Switch
Latching switches are switches that remain in a fixed position when oppressed. It can be used to make or break circuits for continuous usage. Latching switches are primarily seen in homes. The electrical switches you usually use to power on or off are all latching switches.
k. Electric Or Pneumatic
Electric or Pneumatic itches use air pressure to work. When you press the switch, the air is compressed, sending a small huff of the air through a tube to the switch. The air puff activates the air switch and breaks off the electric circuit, activating the connected device.
Electric or pneumatic switches include foot switches, hand controls, bellows switches, etc.
What Are The Parts Of A Push Button Switch?
Push buttons usually have five parts-
- Operating part: It is the part that relays or connects the external operating force to the central switch unit.
- Mounting part :The mounting part connects the switch to the electric board, wall, or panel.
- The light source: It is a protective case containing the switch’s mechanical parts.
- Case part: We usually touch or press the outer part.
- Switch unit: It is the main work area of the switch that connects with the electrical unit.
What Are The Applications Of A Push Button Switch?
The push button switches come with many applications, including-
- The push button tactile switches are used to make The switches are connected to electric circuits. You can tap on the buttons to operate these. A logic circuit connected to the buttons provides power while you are working on the calculator.
- Mobile phones and telephones also have tactile push buttons. Similarly, TV controllers or remotes are also made of tactile
- Modern ATMs and vending kiosks also come with pushbuttons
- Doorbells and alarm bells- Modern doorbells and buzzer bells are made of push buttons.
- Control buttons- Most of the control buttons of modern electric appliances are push buttons. These buttons are connected by the software program and are usually color-coded to make them user-friendly.
- Hospital beds and wheelchairs also have push buttons.
- Push buttons also operate lights, fans, and many other appliances.
Which Type Of Push Button Is Best?
The best push button you can choose depends on the machine you want to use the button and other criteria like the Maximum AC or DC voltage, the maximum current or power level etc. Each push button has a different purpose and is best in its own way.
Conclusion
Push button switches can make or break the circuit when pressed. These are used for regular day-to-day functioning and even for advanced machines. Push buttons come in different designs and variants, each with different usage.
