What is a toggle switch?
You may not yet know what toggle switches are or how they work, but I’m sure you’ve seen them before. Even if you’ve never seen one in real life, you have watched old war movies before, right? Try to picture an image of those old airplane cockpits or even those old car dashboards. The small shiny levers that the pilots or drivers flip on and off are called toggle switches.
A toggle switch is an electromechanical device that switches a circuit on and off or switches between multiple circuits by flipping a lever back and forth.
Toggle switches come in many shapes, sizes, specifications, poles, and throws. But we’ll get into these further on in the article.
What are toggle switches used for?
There is an endless number of uses for toggle switches. Most areas that require switching between or in and out of circuits could technically employ the use of a toggle switch.
Toggle switches are one of the most popular types of switches available. They are cheap, convenient, and simple.
This does not mean they are ideal in every circumstance, however. A toggle switch may not bring out a certain look on a control panel and so may not be the ideal type of switch to use in certain areas.
The airplane cockpit, for example, is a popular area that employs the use of toggle switches. Other control panels for mobile or stationary equipment are also areas in which toggle switches can be found. Musical equipment such as amplifiers and electric guitars usually make use of toggle switches as well.
The world of DIY and customization also uses a lot of toggle switches such as in custom race cars.
Even modern interiors like the new Mini Cooper use toggle switches to give it a classical look.
Toggle switches have become less popular in consumer items which designers try to give a futuristic look, but they are still staples in the commercial and industrial sectors.
Types of Toggle Switches
As with any other electrical component, it is always important to consider the specifications of your circuit when purchasing a toggle switch. Toggle switches are available for various voltages, amperages, power and are manufactured using a variety of materials.
Apart from the rating, toggle switches are mainly grouped based on their operational designs.
They can be described according to the number of distinct positions that the levers can be switched into. The simplest form is a 2-position toggle switch. This is usually on and off.
Toggle switches are also popularly found in 3-position types as well. This is where the simplicity stops.
There exists 4-positon, 5-position, 6-position, and as many as you can design a circuit tod need, you can have it made. These multiple position toggle switches are manufactured for specific uses however and are not as easy to source.
The more popular way to classify toggle switches, however, is based on the number of poles and the number of throws.
Pole refers to the number of separate circuits that the switch can control at the same time.
Throw refers to the number of different outputs that each switch can connect its input to.
Under this definition, the types of toggle switches are SPST, SPDT, DPST, DPDT, and special switches that are not classified under the four popular headings.
SPST (Single Pole Single Throw) Toggle Switches
SPST toggle switches operate one circuit. It has two operational positions which are ON/OFF. Switching between these two positions either closes or opens the connection between the conductors connected to its two terminals.
SPDT (Single Pole Double Throw) Toggle Switches
There are two variations of single pole double throw toggle switches. They are the 2-position ON/ON and the 3-position ON/OFF/ON variant.
This is a 3-terminal switch which also controls just one circuit. The center terminal, known as the common is connected to the input. The two outer terminals are the output, often referred to as A and B. The switch lever has two positions, meaning it can connect the input to either terminal A or B.
This is also a 3-terminal switch that controls one circuit. Just like SPDT ON/ON, the input is connected to the common. The only difference with this switch is that there are three positions of the lever. The end positions switch the circuit between terminal A and B. The center position, however, is an off position. This means that it does not connect the input terminal to either of the outputs.
DPST (Double Pole Single Throw) Toggle Switches
This is essentially two SPST switches put together and controlled by the same lever. This type of switch contains four terminals: two inputs and two outputs. They operate as ON/OFF switches.
A popular use for DPST switches is with 220V equipment where they are used to open or close both 110V lines simultaneously.
DPDT (Double Pole Double Throw) Toggle Switches
There are three popular types of DPDT toggle switches. There is the 2-position ON/ON and there are the 3-positions ON/OFF/ON and the ON/ON/ON.
This consists of two SPDT ON/ON switches fabricated together to be controlled simultaneously by one lever. It is a 6-terminal switch with two separate circuits. The input or common terminals are either connected to both A terminals or both B terminals at a time. There are only two positions on the lever.
This switch also has six terminals and control two separate circuits. The lever, however, has three positions. The two end positions connect the inputs to either both A terminals or both B terminals at a time. The center position, however, does not connect the input to any of the output terminals, creating an open or off circuit.
This one is a little tricky. It is also a three-position switch with the center terminals receiving the input. The two end positions of the lever connect the input to either both A terminals or both B terminals at once. The center position is what makes this switch unique. When the lever is centered, one of the inputs is connected to its respective A terminal and the other is connected to its respective B terminal. The switch therefore only moves one circuit at a time as it is moved to the center position.
There is a type 1 and a type 2 which is used to differentiate which side switches over first. These switches are most commonly used on electrical guitars.