Pushbutton switches enjoy ongoing popularity, even despite the fact that touch screens are still very popular. This is thanks to their durability, intuitive operation, as well as mechanical endurance. Moreover, they often turn out to be more comfortable to use than their new alternatives.
Marquardt delivers a wide variety of electromechanical components. Their precise and robust design fully satisfies the needs of applications in fields such as general industry or heavy machinery. However, they still can be successfully used in consumer devices. They primarily include switches, used to connect power and automation circuits, as well as to construct control panels and interfaces. It’s a very wide assortment, so TME decided to present a comprehensive overview in this article. The majority of Marquardt products available in the TME catalogue have been described below, including less common but still attractive solutions.
In this article, we discuss topics such as:
- Rocker switches for power circuits
- Illuminated TACT SWITCH buttons
- High-current pushbutton switches
- Construction of interfaces and non-standard keyboards
- Practical applications of door switches
- What is a dead man’s switch?
- Advantages of neon lights in industrial indicators
Rocker switches
One of the largest groups of products by Marquardt available in the TME catalogue comprises rocker switches, i.e. typical rocker-type components which can be used in a wide range of applications: mostly to connect power circuits, but also to select a task, send signals to the controller and much more. They are available in many variants, which is thanks to the number and diversity of their functionalities. Above all, note that they are available in mono-, 2- and 3-stable variants. As a result, they come with different contact configurations (including SPST, DPST, DO3T) designed to operate at a current of up to 20A and the standard mains voltage of 250V AC. Some of them feature a semi-transparent front and a built-in illumination – such products are available in many colour variants. Thanks to the illumination, they combine functions of a switch and an indicator. With their help, an operator who stands at a distance from the control panel can easily see which circuits are connected.
The majority of this type of Marquardt switches have been designed for panel mounting. That’s why they boast a high level of ingress protection (from the front), which can even reach IP67 rating (full dust ingress protection and protection of contacts against flooding and moisture). Thanks to that, you can mount these switches in harsh environmental conditions, even if they are going to be subject to rain (construction site power tools, outdoor control panels for cranes, crushers, etc.). You can simply connect such models using standard flat connectors (3, 4.8 or 6.3mm). Another group of Marquardt rocker switches are components designed for direct mounting on a PCB, which facilitate the construction of compact control or power modules (also used in consumer devices). They are mounted in the same way as other through-hole components (THT).
Microswitches
The category of microswitches comprises a few types of components. Marquardt primarily supplies SNAP ACTION microswitches, that is monostable switches equipped with a spring-loaded mechanism, which also offer fast actuation time. They require a relatively low actuation force (and boast mechanical endurance). In fact, they are among the most common signal and interface switches. They are also used to detect the position of machine components and to count various items – this applies especially to models equipped with a lever and a roller, which guarantee low-friction movement (while the lever made from metal that springs back additionally absorbs the pressure). Note that despite their small size, some products from this category can operate at a current of up to 10A and a voltage of 400V (some products offer even higher rating). Thanks to all that, the switches can be used to directly control high loads (lighting, motor), while SNAP ACTION switches can be applied in protection circuits, where the change of their position will stop the machine by disconnecting it from power supply.
Microswitches also include TACT SWITCH components, very often used in electronics, known mainly as parts of control panels in consumer electronics and household appliances etc. However, Marquardt products from the 3006 series really stand out when compared to their competition, as these switches are integrated with illuminating LEDs. Their maximum profile height is 4mm, while the base is a square with the sides of 9.85mm. Such a compact casing incorporates an independently powered LED covered with a transparent button. This combination offers plenty of possibilities in terms of developing functional and visually attractive interfaces, even if the designer can only use little space on a shallow panel or a limited volume of an enclosure.
Standard pushbutton switches
Pushbutton switches are another popular type of switches. Just like rocker switches, they are available in bistable and monostable variants. This allows for them to be used in multiple environments: control devices (i.e. cranes), control consoles and other demanding equipment, primarily in industry. Pushbuttons offered by TME are available in several colour variants, and they can also be illuminated. They can have round (snap-in panel-mounted) or square bodies (screw-mounted). As for their electrical parameters, you can expect the same high quality as in the case of the abovementioned products. Their contacts (usually silver-plated) can handle currents ranging from 0.1 to 16A at a rated voltage from 28 to 250V AC (depending on the model), which means that they can operate with most mains loads. We would like to highlight the broad range of available products that can operate in a wide spectrum of temperatures (i.e. from -20 to 100°C). Together with the switches, the TME catalogue has been expanded to also feature compatible protective caps and covers, preventing damage related to water, dust, etc.
Slide switches
Marquardt slide switches are available in 2- and 3-position variants (SP3T contact configuration). Depending on the model, they can be configured to switch on the mains supply (up to 2A at a rated voltage of 250V AC, with the terminal in the form of connectors) and to work with electronic circuitry. The latter are PCB- (THT) or panel-mounted (the switch body features suitable mounting holes). The leads of panel-mounted switches are designed for soldering wires to them.
Toggle switches
Toggle switches have several key advantages: the user can easily tell their position, they are easy to use, giving a clear, tactile indication of switching. Additionally, their design allows for the safe closing of high voltage circuits (up to 10A in the case of the Marquardt products). The actuating lever can be either narrow or wide. Similarly to most of the products described here, the switch terminals have been made with the use of flat connectors or soldering leads. Most of the offered models boast excellent thermal tolerance (i.e. -25…70°C or -20…100°C). They are available in 2- and 3-positions variants (1 to 3 stable positions). It is worth mentioning that the manufacturer provides toggle switches with bodies designed for mounting in both round and, less typically, rectangular openings.
Keypad switches
Under the category of keypad switches, you can find both electromechanical components and compatible keys. Such products are used to build complex, specialist interfaces for machines, control panels, electronic equipment (such as cash registers or shortcut keypads). Keys come in several variants: solid, with an opening for a signal diode, and with a removable, transparent panel, under which you can place a printed symbol or description and in this way adapt the keypad to any application at low cost. Naturally, keypad switches have a low current capability (up to 0.1A at a rated voltage of 28V DC) because in most cases they will cooperate with digital circuits, arranged into a matrix. Selected products have been equipped with an independently powered LED, in a red, yellow and green colour variant.
Door switches
Door switches are a special kind of pushbutton switches. As the name implies, they are designed to detect the opening of doors and covers, opposite to safety switches. Among other things, this allows for turning on the lights in rooms or illuminating lockers and poorly lit places. Such switches can also serve as a part of alarm and anti-theft systems. Due to their intended purpose, they are designed to handle high currents (16A/ 400V) and they are enclosed in compact bodies with mounting holes. Thanks to the latter, they can be mounted firmly and precisely to a wall or a door frame in the desired place and position. The door switches are available in white and black colour variants.
Foot switches
Foot switches are most commonly used for two purposes: activating manually operated machines (i.e. pneumatic anvils) or as a dead man’s switch. The latter is an element which is used to ensure that a person operating a device is still capable of doing so, i.e. they didn’t lose consciousness. Such safety measures are employed in devices which must be supervised, in places such as production lines, tramcars, railway or amusement parks. They are available only in a monostable variant, where both closed and open circuit can serve as a momentary position. While most models feature connections in the form of screw terminals, manufacturer also offers variants with pre-installed wires (3m) and power connectors (European standard), which enables the switch to handle common, ‘socket-powered’ devices. Due to their intended purpose, foot switches are designed to work at a relatively high load (up to 14A at 250V AC).
Neon indicators
Indicators with a neon lamp as a light source are a solution that is known and employed in many devices – it is one of the oldest and most popular solutions in industrial systems, home appliances, and even heavy and transport machinery. Their main asset is the ability to connect them directly to power supply lines, since they are designed to work at the rated voltage of up to 230V AC. What’s more, they boast an excellent resistance to interference and voltage spikes, as well as low power consumption. Typically, the current that flows through a neon indicator doesn’t exceed several mA. Another benefit of choosing Marquardt indicators is that they feature a built-in current limiting resistor, which is required for the lamp to operate properly. The face of the housing is semi-transparent, available in green and red versions. Flat connectors are used to connect the element to the circuit. The indicator is panel-mounted, with a snap-in fixing, and can be mounted on walls that are between 0.75 and 3mm thick.
