On the surface, selecting the correct switch for a given design might seem like a relatively simple decision and there’s certainly no shortage of switch types to choose from or ways of using them, with a huge range of assorted types, styles, colours and sizes, even in the specialist rugged category. However, pick the wrong one and you’ll suffer the consequences, whether through negative user perception of your product, or, worse still, a complete system failure.
It all comes down to those all-important design decisions. In considering the design process to be a series of choices, designers can work through a method of thinking that breaks down the application to its essential components. Only by assessing what the switch is being used for and how and where it will be used, taking into account environment, operator, space and ergonomics along the way, can designers arrive at the best switch for the application?
How will you be using the switch?
A component in an electrical or electronic circuit, a good place to start is to look at the switch’s function within that circuit. Is power being routed through the switch or is it being used for logic levels where the power rating is unimportant? If it’s power you’re after, then voltage and current rating will be your primary considerations.
Other factors to weigh up are switch contacts, operating life and the type of signal to be carried. Should it have a single pole or two, or more? Are the contacts to be open or closed, and will the action be momentary or latching? Is a particular bandwidth or shielding required? Where operating life is central to overall reliability, it’s important to fully understand the role of the switch in order to get the requirements right: a master power switch might be used relatively infrequently whereas a switch to select menu items could be used repeatedly and require a correspondingly longer rated life.
Where will you be using it?
It’s a tough world out there and your humble switch may be destined for a harsh habitat. Will it be located outside and exposed to the weather? If so, it will need to be resistant to moisture or dust. It is heading for a tough indoor environment within heavy industry or food manufacturing where equipment is regularly washed down? A sealed switch may well be the answer. Will the user be wearing gloves? Then designers might want to consider piezoelectric switches that only require pressure to operate, rather than skin-to-metal contact.
Who will be using the switch?
Choosing a switch that’s going to be used on hi-fi equipment, say, in someone’s home, is a very different scenario to selecting a switch intended for use in a public space. Those used by the general public will be subjected to a much harder operating life – sometimes even deliberate damage – and a more robust type should be selected.
How much space have you got?
As end users demand ever-expanding functionality within an ever-decreasing form factor, space becomes a significant challenge for designers and a key influence on the type and size of switches available for consideration. With space at a premium, it might even be better to avoid switching power on the front panel altogether, opting for a smaller switch to control a remote switch elsewhere in the application.
However, ergonomics is another key element for designers to bear in mind, where the choice of switch can make the difference between a front panel being user-friendly, or not; and that’s before you start considering ease of use for the mobility or visually impaired, as well as colour and branding. In addition, designers can now add low-power LED technology into the selection mix and consider the benefits to their applications of using illuminated switches that are useful in low light settings and as a ‘power on’ indicator.
Will it carry a legend?
Another space-saving tip is to choose a switch with a pre-printed legend, saving panel space and allowing for a common front panel design to be used in multiple products or settings, saving cost in the process too.
Likewise, there’s certification. Mains rated switches often carry electrical safety approvals and, together with other commonly used certifications relating to materials or IP ratings, selecting these switches frees up designers to consider other issues around space and ergonomics.
Optimum solution
At first glance it might seem something of a switch-choosing conundrum, but in understanding the application, the environment within which it will operate, and in considering all possible use cases for their switch of choice, designers can arrive at the optimum switch solution.
Bulgin has an extensive range of push button, vandal-resistant, piezo, slide, toggle and rocker switches which will meet the needs of a wide variety of applications including those found in the medical, industrial, marine and commercial sectors. The push button switches are available in front and rear panel mounted versions with three profile types including prominent, domed and low profile. A comprehensive range of rugged and vandal-resistant stainless steel push button switches are also available as well as IP66, IP67 and IP68 sealed products.
Visit Bulgin’s Connectivity Community forum and blog for expert advice on switches.