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sensors:on-off_switch [2018/11/01 18:55] (current)
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 +====== On-Off Switch ======
  
 +<note important>​
 +This article has an insufficient **[[wp>​Harvard_referencing|reference list]]**. Please help by adding the appropriate references to this article, especially if you were involved in writing it!
 +</​note>​
 +
 +<note tip>
 +This article needs to be **cleaned up** to conform to a [[wp>​Category:​Wikipedia_style_guidelines|higher standard]] of quality. Please help SensorWiki by editing this page.
 +</​note>​
 +
 +===== Summary =====
 +==== Introduction ====
 +The simple yet robust **on-off switch** (also called a **binary switch** or simply a **button**) is perhaps the most commonly used control component since the development of electronic technology. ​ It is often implemented in experimental instruments such as keyboards and wind controllers to determine whether the user has depressed a key.  It should be noted however that pure binary switches are not usually present in acoustic instruments,​ and so subtleties such as dynamics (in the case of the piano) and half-holing (in the case of wind instruments) are not captured by switches. ​ A notable exception is the harpsichord,​ in which case each key is in fact a binary switch that triggers an envelope pre-determined by the construction of the instrument.
 +
 +==== Switch types & construction ====
 +The switch works on the principle of creating or breaking an electrical connection by moving two metals in or out of contact. ​ They can come as normally open (NO) or normally closed (NC).
 +
 +
 +==== Output ====
 +The most important consideration with the output of a button is constructing a debouncing circuit. ​ When a button is pressed, the metal conductors actually come in and out of contact several times on a micro-scale before settling into a static position. ​ Depending on the use of signal, this can result in strange or noisy [[attack transients]],​ or be registered as several logical events rather than one.  A debouncing circuit compensates for this by allowing current to pass only after contact has been made for a specific amount of time (for instance, 20 ms).  Common methods of debouncing:
 +  * Filter circuit containing a resistor and capacitor in series
 +  * Schmitt trigger
 +
 +===== Devices =====
 +
 +=====  External links & references =====
 +
 +{{tag>​Switch}}