08-16-2017, 09:32 PM
Electric Bell
Coffee call there is a mechanical Bell that operates by means of an electromagnet. When an electric current passes, this produces a repeated buzzing sound or l zga ij. Electric calls are widely used at railway crossings, in phones, fire alarm and security systems, and school bells, door bells, and anxiety in industrial enterprises, but now they are commonly replaced with electronic echo.
Types Of
shortstop Bell
As the circuit breaker type electric Bell works.
The most widely used form is the shortstop Bell, which produces a continuous sound when current. See animation, right. Bell or Gong (B), which is often in the form of cups or hemispheres, is amazed with the spring bracket (A) with a metal ball at the end is called a plate, driven by an electromagnet (E). In the initial position the Bell ringer is within walking distance of his elastic hand. When an electric current is run through the winding an electromagnet (after closing the switch (K), i.e., pressing the door) that creates a magnetic field which attracts the iron Bell by pulling on the arm to give a call, press. This opens up a couple of electrical contacts (t) attached to a ratchet arm, interrupting the current to the electromagnet.The magnetic field of an electromagnet is destroyed, and the spring plate from the bells. This once again closes the contacts that allows current to flow in the solenoid is again, so the magnet pulls the plate over to hit the Bell again. This cycle is repeated quickly, many times per second, resulting in a continuous ringing.
The tone of the sound is generated depending on the shape and size of the Bell or Gong resonator. If multiple bells installed, they can be given distinctive rings with a different size or shape of a gong, although the mechanism of impact are the same.
Another type, one stroke of a Bell, does not have the terminating contacts. Hammer hits the Gong once each time it closes the circuit. They are used to signal the brief notice, such as shop opening doors for the client, not the continuous warnings.
Calls
Coffee call a similar mechanism is used for circuit breaker Bell, but without the resonant bells. They are quieter than the Bell strikes, but enough to prevent the tone in the short distance, for example, through the desktop.
Buzzer or beeping sound signaling, which can be mechanical, electromechanical, or piezoelectric. Typical areas of use of buzzers and alarms include alarm devices, timers, and confirm user input such as mouse clicks or key presses.
With the development of low-cost electronics with the 1970 's, most of the buzzers have already been replaced by electronic "probe. These replace the electromechanical Bell striker with an electronic oscillator and loudspeaker, often of the piezoelectric transducer.
Single-stroke Bell
Single-stroke Bell for railway signalling
The first commercial electric bells have been used for railway signalling, signal boxes. Integrated Bell codes were used for designating types of train, between signal boxes, and the goals to which they must be sent.
These were one-stroke bells: current electromagnet pulled a plate of Bella against Bell or Gong and gave one ring a Bell not ringing constantly, but with only one ring, until the current was not applied again. To maintain tone, these bells were generally much more than today for use with breakers of the bells. Bells, gongs and chimes all spiral can be used, giving a great tone for each tool.
Easy development of one of the Bell jumped the Bell. It previously used, power-operated for the bells servant calls in large houses. Instead of working with the plate, the solenoid has shaken the whole Bell, which was mounted on a flexible spiral spring. the inertia of the heavy bells on a light spring will continue to call for a few seconds after a stroke. Though the sound will quickly fade away, you can see jitter Bell can indicate which had rung the Bell, among a group of a few.
Cell Phones
Where Bell is powered by AC power of various designs, polarized ring can be used. They have a frame that contains a permanent magnet, so it is alternately attracts and repels each half of the phase and the other polarity of power supply. In practice, the anchor are designed with symmetrical circuit traces two poles of opposite polarity to each end of the coil, so everyone can be involved in turn. No-contact switch is not required, the bells are reliable for long service. For this reason, they are widely used for telephone bells.