Design of a pre voltage amplification circuit in an audio power amplifier 10

This one. The basic design method is in the textbooks such as analog circuits, and it is too troublesome to go to Xinhua to read the textbooks of the university.

Quanzhou** sells wheelchairs for dogs? My dog can't walk on the back legs, I have seen it on the Internet and there are sold outside the province, I don't know if there is one in Quanzhou?

Japan's human-powered tricycle is a great fit, which is a smaller vehicle than a small domestic tricycle that can carry two pet dogs. In Japan, it is used by housewives to buy groceries and take pets out. It's probably a little wider than an adult's shoulders.

There are simple manpower, there is electric assistance, pay attention to the power assist, you don't ride, the motor does not turn, it is very safe, this is the standard requirement of Japan and Europe.

Purely human, the good one is a double flywheel.

There are smugglers, I have seen a lot, from the old 600 yuan to the relatively new 3,000 yuan, and even the 5,000 yuan to help the 5,000 yuan.

Because transportation takes up several times more space than ordinary bicycles, the average person does not traffick.

I'm an office worker and climb stairs.

I am an office worker, but the company does not have an elevator, only the stairs are 9 to 10 floors, and people say that climbing the stairs hurts my knees a lot! What to do?

Who has a secret to climbing stairs without hurting their knees?

Please let me know if you have!

Don't tell me to quit my job or something.

I can't afford to play! Thank you for the kindness.

Thank you. In a few years, I may be able to make a stair-climbing robot for my own use, there is no design barrier, only the limitation of processing costs; The standard structure is a cast aluminum structure, hollowed out with a CNC center, the cost is unaffordable, and only small pieces of material can be cut by hand, connected with a domestic gas shielded welding machine, and the gear pair can only be used ready-made.

Referring to aluminum alloys, it is necessary to search.

Why use aluminum alloy for computer cases.

Referring to wheelchairs, it is necessary to retrieve.

What exactly is Segway and what are its details?

1 A new American wheelchair that can climb stairs.

The last link is in the Tieba > Electric Stair Climber Bar.

It can be seen that the research cost of the above two advanced means of transportation from the United States is more than 100 million US dollars, and it is not a commercially profitable and valuable subject.

If someone has made a practical electric stair climbing car for you, even if there is no autonomous movement ability (for example, parked upstairs, you summon it downstairs to come down to carry you on its own), even if there is no gyroscopic system (do not have a complete space attitude stabilization system, but it will not capsize in the process of carrying people), its value is more than a high-end Mercedes-Benz, BMW, Porsche sedan. Do not rule out the use of 5,000 yuan or more material costs and external processing costs to make a simple stair climber, you to the post bar > electric stair climber can see a lot of ** advertising, there will be many functions lacking, with a manufacturing cost of 5,000 yuan, it is absolutely impossible to surpass the above two core functions of advanced transportation from the United States.

1. The preamplifier refers to amplifying the audio (aux, mic) signal to the input range that the power amplifier can accept.

The preamplifier has two functions: one is to select the desired source signal and amplify it to the rated level; The second is to carry out various sound quality controls to beautify the sound.

The basic components of the preamplifier are: sound source selection, input amplification, sound quality control and other circuits.

2. Audio amplifier is one of the important components of multi-class products, which is widely used in the field of consumer electronics. Linear audio amplifiers have been dominating the traditional audio amplifier market due to their low distortion and good sound quality. In recent years, with the popularization of portable multi-class equipment such as PDA, mobile phones, laptops, etc., the efficiency and volume of linear power amplifiers can no longer meet the requirements of the market, while Class D power amplifiers are more and more favored by people with the advantages of high efficiency and small size.

Therefore, the high-performance Class D power amplifier has very important application value and market prospects.

Summary. Design TechniquesThere are many ways to design a high-quality audio system using National Semiconductor's audio drivers. The following are design recommendations.

Input Stage: The input stage design is the most critical part of the amplifier. By subtracting the signals from the feedback, the input stage generates an error signal, which is then driven to the output.

This error signal is usually small enough to provide sufficient linearity for the amplifier.

Dear Hello, we are happy to answer your questions, Guan Wu disturbs the design problems of audio amplifiers, and many traditional high-power audio amplifiers have an output power of more than 100 watts per channel, and most of them use separate circuit components. Therefore, in order to ensure the stability and sound of the output, engineers often need to put a lot of effort into matching and adjusting the high-fidelity audio amplifier.

Design TechniquesThere are many ways to design a high-quality audio system using National Semiconductor's audio drivers. The following are some of the design recommendations. Input level:

The input stage design is the most critical part of the amplifier. By subtracting the dust from the feedback signal, the input stage generates an error signal, which is then driven to the output. This error signal is usually small enough to provide sufficient linearity for the amplifier.

I would like to ask if the base voltage difference of the complementary symmetrical circuit of the composite tube should be set?

Pro, the base voltage difference of the complementary symmetrical circuit of the composite tube should be set to.

Now the power amplifier, the output power has different values according to different needs, and the input terminal is unified (1V root mean square value), different signals are generated by different devices, and the sensitivity is not the same, which needs to be processed to the power amplifier input interface, this level is pre-positioned.

At the input end of the power amplifier, the input voltage is specified as 1 volt, and the sensitivity of various pickups is different, such as the microphone 5-10mmV, and 40 decibel voltage amplification is required to connect with the power amplifier. There are also mixing, tone, electronic crossover, etc., all of which are attributed to the front circuit.

Very simple circuit, typical common emitter amplifier.

A 3V voltage source provides the power supply, R1 provides the base bias, R2 forms a common emitter amplifier with a triode, and two capacitors are used to isolate the DC signal and provide the AC signal path.

The input signal is transmitted to the base of the triode through capacitive blocking, and then output at the collector after being amplified by the triode, and then sent directly to the horn through the capacitance barrier.

The pre-stage voltage and current amplifier is generally a voltage amplifier, which amplifies the amplitude of the weak small signal to a certain extent, so that it is easy to lap with the post-stage and amplify the current to a large extent. The general voltage amplification of the post-stage is not large, and the main amplification current is the main one. That is, the so-called power amplification, there is no pre-amplification stage, and the signal is too weak to drive.

Voltage amplifiers are strictly called transformers. Because it can increase the output voltage or reduce the output voltage to adapt to different circuit voltage requirements.

As the name suggests, a power amplifier amplifies a small signal to control or achieve the needs of the electrical appliance to be controlled.

The preamp is generally a voltage amplifier.

Amplify the amplitude of a small weak signal to a certain extent.

Easy to lap with the rear stage.

The amplification is very small.

The general voltage amplification of the post-stage is not large.

It mainly amplifies the current. This is the so-called power amplification.

There is no preamp. Directly connected to the power amplification stage.

The signal is too weak. Can't drive.

The emission follower is the amplification of the current action.

The voltage amplification factor is less than one.

That's what the Shooter Follower means.

The emitter voltage is the base voltage.

regardless of the size of the load).

Oh, your idea is right, but the amplification circuit is to amplify the voltage before the current can be amplified, the reason is that the output current of the transistor is controlled by the input current, and the input current is controlled by the input voltage The question you asked is very good, the co-emission amplification circuit is indeed a kind of power amplifier circuit, the power amplifier is divided into class A, CLASS B, CLASS A and B, CLASS C co-emission amplification circuit belongs to class A power amplifier, it is characterized by small signal output distortion, and the disadvantage is that it wastes electricity, because it must work at a static working point, Therefore, the total output power is up to 50%, and the output distortion of Class B signal is obvious but power saving, so the output power is not more than 75% at most, and the combination of the advantages of these two types is Class A and B, but its disadvantages are the same as Class B, the advantage is that half of the waveform can be output without distortion, so in order to make up for this shortcoming, the current use of Class A and B complementary symmetrical power amplifier circuit, so the reason why the power amplifier is now used is its high output efficiency and power saving.