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2. Doorbell - Wikipedia

   en.wikipedia.org/wiki/Doorbell

   Doorbell mechanism from 1884 in Andrássy Avenue, Budapest Antique mechanically operated shop doorbell on a torsion spring. William Murdoch, a Scottish inventor, installed a number of his own innovations in his house, built in Birmingham in 1817; one of these was a loud doorbell, that worked using a piped system of compressed air. [1]

3. 1A2 Key Telephone System - Wikipedia

   en.wikipedia.org/wiki/1A2_Key_Telephone_System

   For key system operation these sets were equipped with a set of push-buttons (keys) and additional internal contact springs to control the additional operational features, resulting in a large variety of specialty telephones. Specifically, such telephone sets were the types 565 (up to 5 lines), 630 (17 lines), 631 (29 lines), 830 (9 lines), and ...

4. Telephone keypad - Wikipedia

   en.wikipedia.org/wiki/Telephone_keypad

   A telephone keypad is a keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number. It was standardized when the dual-tone multi-frequency signaling (DTMF) system was developed in the Bell System in the United States in the 1960s – this replaced rotary dialing , that had been developed for ...

5. Push switch - Wikipedia

   en.wikipedia.org/wiki/Push_switch

   A push switch (button) is a momentary or non-latching switch which causes a temporary change in the state of an electrical circuit only while the switch is physically actuated. An automatic mechanism (i.e. a spring ) returns the switch to its default position immediately afterwards, restoring the initial circuit condition.

6. Push-button telephone - Wikipedia

   en.wikipedia.org/wiki/Push-button_telephone

   A push-button telephone is a telephone that has buttons or keys for dialing a telephone number, in contrast to a rotary dial used in earlier telephones.. Western Electric experimented as early as 1941 with methods of using mechanically activated reeds to produce two tones for each of the ten digits and by the late 1940s such technology was field-tested in a No. 5 Crossbar switching system in ...

7. Push-button - Wikipedia

   en.wikipedia.org/wiki/Push-button

   A push-button (also spelled pushbutton) or simply button is a simple switch mechanism to control some aspect of a machine or a process. Buttons are typically made out of hard material, usually plastic or metal. [1] The surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed or pushed.