Power circuit diagram of telephone?

The most basic telephone circuit diagram is as shown in the figure:

Basic structure

Telephone is a kind of terminal equipment that transmits sound in two directions through electrical signals. The improvements and inventions of telephone in history include: toner microphone, telephone switchboard, dial, automatic telephone exchange, program-controlled telephone exchange, dual-tone multi-frequency dialing, voice digital sampling and so on. New technologies include ISDN, DSL, analog mobile phone and digital mobile phone.

Basic key

Telephone power cord, telephone line, take-up switch, receiver, repeater button, microphone, local number plate, ringtone and hands-free speaker, memory code key, memory number plate, numeric key, memory retrieval key, memory storage key, redial key, work indicator, hands-free key, R key, hands-free transmitter, ringtone adjustment switch, P/T switch and hands-free receiving volume adjustment knob.

principle of operation

Telephone communication is a communication technology that uses electricity as the medium and transmits language through the mutual conversion of acoustic energy and electric energy. The simplest way for two users to communicate is to connect two phones with a pair of wires.

When the speaker picks up the phone and speaks into the microphone, the vibration of the vocal cords excites the air to vibrate, forming sound waves.

Sound waves act on the microphone to generate current, which is called speech current.

Voice current is transmitted along the line to the receiver of the other party's phone.

The function of the receiver is just the opposite of that of the microphone-it converts the current into sound waves and transmits them to people's ears through the air.

In this way, the simplest call process is completed.

Development history

The telephone was invented by American A.G. Bell in 1876. He used two wires to connect two transmitters and receivers with the same structure and a diaphragm on the electromagnet, which realized the communication between the two ends for the first time. But the call distance is short and the efficiency is low. Carbon microphone appeared in 1878, which greatly improved the efficiency of telephone microphone. The receiver structure has also been improved. The earliest telephone was a magnet telephone, which was powered by its own battery and sent a call signal with a hand-cranked generator. 1880 * * electric telephone appeared, which was powered by * * * electric switch in a centralized way, saving the hand-broadcast generator and dry battery. 189 1 year, rotary dial-up automatic telephone appeared, which can send out DC dial-up pulse, control the action of automatic exchange, select the called user and automatically complete the transfer function. Thus pushing telephone communication to a new stage. By the end of 1960s, push-button all-electronic telephone appeared. In addition to pulse signaling, DTMF signaling also appeared. With the development of program-controlled switches, dual-tone telephone is becoming more and more popular. Electronic telephone circuits are developing towards integration, and telephone application specific integrated circuits have been widely used in various components of telephone circuits. Various multifunctional telephones and special telephones have also emerged. By the early 1990s, there had been a telephone which integrated the functions of dialing, talking and ringing on an integrated circuit. With the development of speech recognition technology, a new type of telephone that dials directly by voice is also emerging.

The original telephone (terminal) was a magnet telephone composed of a micro-generator and a battery. When making a phone call, the user uses the hand-cranked micro-generator to send an electric signal to call the other party, and the other party connects the phone to form a call loop. Later 1877, T.E. Edison invented the carbon microphone and induction wire, which extended the communication distance. That same year, the telephone was invented. 189 1 year, finally developed into a.b. strowger who invented the automatic telephone.

fundamental function

The telephone is set at the beginning and end of telephone communication, and it is the user terminal equipment of telephone network. Modern telephone can easily realize the conversation and dialogue between end users, which is formed by many people's research and countless improvements in 100 years. Although their styles vary widely, they generally have the following basic functions:

1, sound and electricity intercommunication

Because of the high communication speed and long distance, it is impossible to transmit sound directly, so we must first turn the sound into an electrical signal (that is, take electricity as the carrier).

When you reach the other side, you can restore the electrical signal to sound.

2. Off-hook identification

When the calling party picks up the phone, the switch should have the function of knowing that "someone wants to call" so that the switch can prepare for the connection.

Step 3: Send a signal

An automatic telephone directs the operation of the telephone exchange by sending a dialing signal, and then establishes a connection between the two telephones.

Step 4 ring the doorbell

That is, when the other party calls, the phone can tell the host by ringing: "Someone is calling."

5. Electrical connection

In the telephone, the components that realize these five functions are: receiver, fork spring, dial (or press keyboard), telephone bell and telephone circuit in turn.

Main classification

wire telephone

The telephone has the function of converting the sound wave of the terminal into an electronic signal, transmitting it to a distant party through a telephone line, regenerating the electronic signal transmitted by the other party into voice (sound wave), making it talk, and sending a signal (dialing pulse) selectable from multiple parties to inform the other party of the calling sound. A telephone consists of a transmitter that converts voice into current and sends it to a telephone line, a receiver that converts current sent by the other party into voice, a dial or button of the calling party, a ringtone that sends a call tone, and a line network that connects these to the telephone line to perform its functions. There is a small box filled with carbon particles in the transmitter, with a thin and hard aluminum alloy vibrating plate in front. The vibrating plate vibrates according to the sound, vibrates the carbon particles, and the carbon particles conduct current. With the contact degree of particles, the resistance changes, resulting in voice current. After the receiver receives the voice current of the other party, it generates magnetic force on the coil caused by the voice current, vibrates the iron vibrating plate and makes sound.

radiophone

Wireless loop-cordless telephone electricity

Telephone master-slave machine

Digital cordless telephone with mobile phone

Analog cordless telephone

mobile phone

radiophone

smart phone

With the rapid development of IT technology, the processing capacity of embedded terminal equipment is getting stronger and stronger. At the beginning of this century, a telephone with personal digital assistant (PDA) appeared.

In addition to the complete fixed-line telephone function, smart phones usually have the functions of large-capacity business card management, incoming and outgoing call management, preventing telephone harassment (telephone firewall), enterprise group telephone business card management (internal business card), and many other functions to assist office work, such as scheduling, notes, calendars, calculators, etc. Early smart phones had the ability to dial-up Internet to exchange information, and realized the functions of sending and receiving short messages. With the development of fixed-line smart phones in China in recent ten years, its processing capacity has been continuously strengthened, and the functions of smart phones have gradually increased.

Smart phones have Internet access and powerful multimedia functions. You can browse the Internet, play audio and video, and have the functions of e-books and electronic photo frames. At the same time, the functions of smart phones in supporting office, marketing and entertainment have been greatly enhanced. On the basis of subverting the traditional fixed telephone, more business functions and PDA functions are realized.

operating environment

Conditions of use

Ambient temperature:-10℃ ~ 40℃.

Relative humidity: 45~95%

Atmospheric pressure: 860 ~1060 mbar

Environmental noise: ≤60dB(A)

engineering data

1, working frequency: 300 ~ 3400 Hz.

2. Pulse on-off ratio: 1.6 0.2: 1.

3. Frequency offset of dual-tone dialing: ≤ 1.5%

4. Dual audio signal level: ① Low frequency group:-93dB; ② High frequency group:-73dB; ③ The high frequency component in the frequency combination is 2 1dB higher than the low frequency component.

5. Ringing level: ≥70dB(A)

6, electroacoustic performance:

(1) At 0 km, the objective transmission reference equivalent is ≥+3; Within 3 km, the objective transmission reference equivalent is ≤+15; At 5km, the objective transmission reference equivalent is ≤+ 15.

② At 0 km, the objective reception reference equivalent is ≥-5; Within 3 km, the objective reception reference equivalent is ≤+2; At 5km, the objective acceptance test equivalent is ≤+2.

③ At 0 km, the objective transverse acoustic reference equivalent is ≥+3; At 3 km, the objective lateral sound reference equivalent is ≥+10; At 5km, the reference equivalent of the target sidetone is ≥+ 10.