What You Need to Know About Switches (2025)

Switches are an integral part of our daily lives, offering both variety and ubiquity. They come in countless forms, from tiny buttons to massive controls, and encompass a spectrum of functions. This diversity, influenced by factors such as mechanical or electrical operation and manual or electronic control, can often boil down to personal preferences in aesthetics and user interfaces.

While electronic switches, rooted in technologies like BJTs, MOSFETs, IGBTs, and other semiconductor designs, are garnering increased attention due to declining costs and expanding features, mechanically operated switches are still the go-to switch solution. This article will delve into switch basics, with a particular focus on physically operated and actuated models, to understand how they bridge the realms of form and function.

Switch basics

The starting point for selecting any switch necessitates a grasp of the concepts of poles and throws. Simply put, poles denote the number of circuits that a single switch can govern, while throws denote how many contacts the switch can select from. This notion is most effectively comprehended through straightforward visual representations.

Figure 1: SPST switch diagram. (Image source: Same Sky)

In the case of a switch featuring just a single pole and single throw, aptly referred to as SPST, it offers control over a solitary circuit, with the switch being capable of simply opening and closing a single contact. Now, let's contrast this with a switch possessing a single pole but a double throw configuration, known as SPDT.

Figure 2: SPDT switch diagram. (Image source: Same Sky)

Within the SPDT switch, there remains a solitary circuit under control, yet the switch can transition between two distinct contacts. In the realm of SPDT, the switch isn't confined to the mere act of opening and closing a circuit but, rather, to the redirection of the circuit itself.

Figure 3: DPDT switch diagram. (Image source: Same Sky)

When it comes to a double pole, double throw (DPDT) switch, a single switch assumes control over two circuits, and each switch within it navigates between two contacts. Although SPST, SPDT, DPST, and DPDT represent the most prevalent switch configurations, there's no theoretical constraint on the number of poles and throws a switch may possess. When there are more than two poles or throws, numerical labels replace the 'S' or 'D'. For instance, a switch offering four poles and five throws might be labeled as a 4P5T switch by its manufacturer. Similarly, a double pole with six throws could be represented as DP6T.

Switch selection considerations

Outside of poles and throws, there are several other switch specifications to consider during the selection process. The below list includes some of the more common features but is by no means exhaustive.

• Size: As alluded to earlier, switches come in many shapes and sizes. From switches that are smaller than a grain of rice to those that are too large to move by hand, size will typically come down to the intended application. Industrial settings often implement larger switches where gloves come into play or fine motion is difficult, while compact, embedded devices usually seek out the smallest switch possible.
• Default State: The majority of switches lack a predefined state, but there are momentary switches, which usually exhibit a pre-set condition, either normally open (NO) or normally closed (NC).
• Positions: This parameter dictates the quantity of switches incorporated within a solitary unit. There may be instances where this concept is mistakenly interchanged with "throws", but it's crucial to recognize that positions signify discrete switches within the same unit, each capable of independent actuation.
• Mounting: Like any electronic component, switches offer a variety of mounting configurations. Surface mount and through styles are usually associated with smaller switches on PCBs, whereas panel mount and DIN rail mount switches tend to be larger. A pivotal consideration in both surface mount and through hole setups is the parameter known as "pitch", signifying the separation distance of the leads. In the context of through hole switches, pitch is of particular significance, as the appropriate pitch allows for use with breadboards.

Figure 4: Through hole switch use on a breadboard. (Image source: Same Sky)

• Actuation: In addition to distinguishing between manual and electronic actuation, switches offer various actuation methods. This could include actuation by hand or utilizing small screwdrivers or tools. However, the most common option will be choosing between a raised or flat actuator level.
• Current and Voltage Rating: Switches exhibit a broad spectrum of voltage and current ratings from a few volts and amps up to hundreds or even thousands. It is imperative to always verify that a switch can accommodate both the expected current and voltage ratings of the intended application.
• Environmental Factors: This typically refers to ingress protection or IP ratings used to indicate a switches’ level of protection from dust and liquid. However, some switches may have increased vibration sensitivity or vandal-proof features.

Types of mechanical switches

The switch types provided below are mechanically operated and actuated, and they are commonly encountered, though not exclusively, in smaller, portable, or embedded systems.

• DIP Switches: Available in through hole or surface mount packages, DIP switches are most commonly an array of SPST switches. They fit well on breadboards and in finished products, enabling semi-permanent selections. They come in piano, slide, and rotary forms used for option settings in devices, especially in industrial applications and development kits. DIP switches offer more options than jumpers and are user-friendly, but not for frequent adjustments.

Figure 5: DIP switch example. (Image source: Same Sky)

• Rotary DIP Switches: As a subset of DIP switches, these have a rotary format for selecting discrete options (usually 4 to 16 positions) and feature either a flat or raised knob. Like linear DIP switches, they're available in through hole or surface mount options. However, unlike linear DIP switches, they can output in BCD or hex. While compact and user-friendly, they offer a single output and aren't meant for continuous use.

Figure 6: Rotary DIP switch example. (Image source: Same Sky)

• Slide Switches: Commonly recognized as power switches, slide switches are operated by sliding an actuator. They are typically SPST and can handle frequent use. While some have multiple poles or throws, this can make precise positioning challenging. Although they have higher capacity than DIP switches, they remain low power and are commonly surface or through hole mounted on PCBs. Occasionally, they serve as more accessible DIP switches in consumer electronics, although balancing ease of use with avoiding accidental actuation can be a challenge.

Figure 7: Slide switch example. (Image source: Same Sky)

• Tactile Switches: Known for their noticeable click, tactile switches are small, momentary buttons designed for low voltage, low current signals. They compensate for their modest electronic capabilities with robustness, offering long lifecycles in the hundreds of thousands or even tens of millions. While typically single pole, they can also feature multiple throws and high IP ratings. Their widespread use in consumer electronics, such as game controllers, remote controls, garage doors, and various industrial applications, underscores their popularity due to their small size and durability.

Figure 8: Tactile switch example. (Image source: Same Sky)

• Rocker Switches: Rocker switches pivot in the middle to toggle between two options, usually not momentary. They commonly serve as power switches for high-voltage circuits with some carrying LED or incandescent bulb illumination for switch status. They can be IP rated for harsh environments. Their straightforward interface and actuation make them popular in consumer electronics, despite a slightly higher cost due to size and features. In industrial settings, they complement toggle switches and may have covers to prevent accidental actuation.

Figure 9: Rocker switch example. (Image source: Same Sky)

• Pushbutton Switches: Pushbutton switches, often called buttons or pushbuttons, feature simple in-and-out actuation. They can be momentary, come in various shapes, and LEDs are often integrated for illumination or indicating the switch's state. They handle a wide range of voltages and currents, typically mounting on PCBs or panels. Their user-friendliness suits public areas with constant users. Pushbuttons can be made rugged, with anti-vandal series and high IP ratings, ideal for harsh environments like elevators or subways. However, their size, LED options, and materials can lead to higher costs compared to simpler, smaller pushbutton switch models.

Figure 10: Pushbutton switch example. (Image source: Same Sky)

• Toggle Switches: Toggle switches are recognized for their extended lever, making them suitable for glove-wearing or situations with limited fine motor control. The prominent lever offers clear visual feedback, eliminating the need for extra LEDs, and their large movements ensure unmistakable toggling. They come in various poles and throws, though they are less commonly configured as momentary switches. Toggle switches are prized for their easy actuation, quick feedback, and safety integration, making them well-suited for industrial or scientific applications. Due to their mission-critical use in aircraft, control instrumentation, and medical equipment, they tend to be more costly.

Figure 11: Toggle switch example. (Image source: Same Sky)

Summary

Switches are fundamental components that play a pivotal role in electronics and electrical systems. This article has provided a comprehensive overview of the key aspects of switches, including their types, operation, applications, and considerations. Whether designing a consumer electronic device or working on a complex industrial project, choosing the appropriate switch can greatly impact the functionality and reliability of a system. Same Sky has a range of switch solutions standing and ready to meet a variety of switching needs.