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The overarching category of today’s article, without which we will not move on, is electric buttons. They are common components in electronics whose job is to control electrical circuits. They are used to open or close circuits, and this in turn allows you to start or turn off various electrical devices. These include, for example, pulse buttons that are activated only when pressed, which you may have just operated while browsing the Botland Blog on your phone’s screen, or locking buttons that remain in their last state even after you release the pressure and until you press them again. Today we will work out monostable buttons and what makes them different from bistable buttons.
How do monostable switches work?
Monostable button
, or monostable switch, is a type of electrical button that is able to switch its state from OFF to ON only when it is pressed, and then returns to the OFF state as soon as the pressure is released. This means that the monostable button is activated only for a short time when pressed, after which it returns to its original state.
It has metal contacts that are separated from each other when the button is not pressed. When, on the other hand, it is pressed, the contacts make contact with each other and close the circuit. Inside the button is a spring that pushes the button outward when pressed. When the pressure is released, the spring returns the button to its original position. Another component is the body, which provides stability and protection for internal components. A monostable button is usually enclosed in a plastic or metal housing that protects it from mechanical damage and dust.
Let’s summarize: when the button is pressed, the spring is compressed, causing the contacts to press against each other. This momentary contact, or circuit closure, allows an electrical signal to be transmitted to a connected device or circuit and activates the corresponding function. When the button is released, the spring pushes the button away and the contacts separate, reopening the circuit and disabling the button. Thanks to this design, the monostable button is capable of generating a brief electrical signal each time it is pressed. A monostable button, on the other hand, differs from a bistable button in that it remains in the ON or OFF position even after the pressure is released until the button is pressed again.
Monostable buttons
are often used to turn on and off devices such as lamps, fans, or other electrical household appliances. We are used to the fact that dialing numbers on cell phones and landlines means entering digits when dialing numbers in just the same way. Other close examples include calculators and TV remotes, where a bistable button would be a nuisance, to say the least. Equally often, monostable buttons are responsible for triggering alarms or signals in warning and door access control systems. It’s hard to imagine the modern arcade aspect of gaming without calling special functions on computers and game consoles, where monostable buttons are assigned as keyboard shortcuts or in-game actions.
Other, much more creative ideas for using monostable buttons increasingly form the foundation of DIY maker projects using platforms such as Raspberry Pi and Arduino. Pressing a button in conjunction with one of these platforms to control music and media playback can, for example, change songs, start a pause or resume playback. A simple alarm system combining a monostable button and an Arduino can trigger a beep or send a notification thanks to the platform’s extensive communication capabilities, of which we have already written much.
Other not-so-obvious, but simple ideas include placing a sensor under the seat or on the door as a presence sensor to create a notification system, adding a stopwatch or timer with an Arduino timekeeping system, RPI and smart home lighting control, and integrating a monostable button with Google Assistant or Amazon Alexa the ability to invoke specific voice commands. DIY electronics is limited mainly by imagination.
What is relatively simple to build is usually reliable. The thing is also relatively. It’s easy to point out some potential common disadvantages of monostable buttons, but there are also ways to counter them. Perhaps the most common issue is attrition due to frequent use. It is a good idea to use buttons made of materials that are more resistant to wear and tear, and to clean the contacts regularly to ensure smooth operation. When the button is pressed, there may be a “debouncing” effect, i.e. rapid changes in the state of the button, which can be interpreted as multiple presses. This can be counteracted with software, for example by adding a time delay, or by using debouncing capacitors on the circuit. Monostable buttons can sometimes be extremely sensitive to mechanical vibrations that can be generated when the button is pressed, and these vibrations can lead to false pulses. Here mechanical vibration filters such as capacitors or resistors will work well. Naturally, all buttons have a limited lifespan, which is sometimes difficult to indicate even approximately, and are susceptible to damage from moisture or liquids – if you are planning any applications in – generally speaking – abnormal conditions, it is worth first familiarizing yourself with the specifications and checking whether the chosen button offers a protection class.
