Although the term “negative feedback” is far from known to everyone, every person faces the process behind it every day. A huge number of examples can be cited. Moreover, interestingly, negative feedback is characteristic not only for living organisms, but also for many technical means. In part, it is only thanks to her that progress exists in the form to which we are all accustomed.
The principle of feedback is being studied in various branches of science. For example, in music, the ability to use feedback (feedback) is especially famous for some rock performers, such as Kurt Cobain, Link Ray, etc. It is studied in biology, mechanics, electrical engineering, radio electronics ... in fact, everywhere. Accordingly, in the global network you can easily find many different answers to the question “what is negative feedback”, but often the answers themselves additionally raise new questions. All this despite the fact that the meaning of feedback is extremely simple.
What is negative feedback? Here are a few life examples. Imagine a person walking on a slippery surface. So he takes one step, then another, third ... and then the leg begins to slip, the center of gravity of the body gradually (it just seems that instantly) shifts - there is a real danger of falling. At this point, certain muscle groups contract, trying in one way or another to compensate for the unstable state. This can be a deviation back or, conversely, several frequent steps forward with the body tilted. However, in this case we described only external manifestations. The internal mechanism of operation is as follows:
- the foot comes to the surface. At this moment, signals are sent to the brain from it, indicating strength (each, without hesitation, determines whether the base is soft or hard), roughness, bias;
- in accordance with the data obtained, the position of the body and the placement of the foot are adjusted;
- but now the leg began to slip. Threat to sustainability. The more intense the slide, the more actively the search and implementation of the optimal method that can prevent a fall is performed.
Positive feedback is used by the skier, who tilts the hull even further, increasing the sliding speed. In turn, a negative relationship counteracts the cause of the change in the system.
By the way, many lovers of computer games know steering wheels with feedback. This is it! The stronger the player turns the steering wheel to the side, the greater the opposition from the side of the internal electric motor he experiences. In this example, current feedback occurs.
Schematically, it looks like this: input - system - output. With any changes in the input data, a corresponding change occurs in the output. The latter, in this case, thus affect the system in order to return it to its original stable state.
Feedback in amplifiers allows you to solve several problems at once: to ensure the stability of amplification regardless of the input signal, to make the entire system fully automatic (feedback is configured only at the initial stage). However, negative feedback in electronics is not always implemented so easily. The peculiarity lies in the fact that the feedback signal entering the system must have time to activate the compensating mechanisms before the input data is changed again. In other words, the feedback performance should exceed the rate of change of the input signal. Therefore, in circuits based on microwave frequencies, a number of difficulties arise. One solution is to synchronize input and feedback frequencies.