The oscillating circuit, in simple terms, refers to an oscillating current capable of generating an oscillating current whose magnitude and direction change with the cycle, and the circuit for generating such oscillating current is called an oscillating circuit. The LC circuit is the simplest of these. The oscillating current cannot be generated by the rotation of the coil in the magnetic field. It is a relatively high frequency alternating current and can only be generated in the oscillating circuit. So what is the working principle of the oscillating circuit? In the next article, Xiaobian will give you a detailed introduction, I hope to help you learn!
The physical model of the oscillating circuit satisfies the following three conditions:
1. The inductor L concentrates the inductance of all the circuits, and the capacitor C concentrates the capacitance of all the circuits, and there is no latent capacitor.
2. The resistance of a circuit is R = 0 (including coils and wires). From the energy point of view, there is no other form of inward energy conversion, that is, the heat loss is zero.
3. The LC oscillating circuit does not radiate electromagnetic waves to the external space when electromagnetic oscillation occurs. It is a closed circuit in a strict sense. Only the mutual conversion between the magnetic field energy of the coil and the electric field energy of the capacitor occurs inside the LC circuit, even if the change occurs in the capacitor. The electric field, the changing magnetic field generated in the coil, does not excite the corresponding magnetic field and electric field according to Maxwell's electromagnetic field theory, and radiates electromagnetic waves to the surrounding space.
The general oscillating circuit is composed of an amplifying circuit, a positive feedback network, a frequency selective network and a amplitude stabilization circuit. The large circuit is indispensable for satisfying the amplitude balance condition, because there is bound to be energy loss during the oscillation process, resulting in oscillation attenuation. Through the amplifying circuit, the power supply can be controlled to continuously supply energy to the oscillating system to maintain equal amplitude oscillation, so the amplifying circuit is essentially a transducer, which serves to supplement the energy loss.
The positive feedback network is indispensable for satisfying the phase balance condition. It returns some or all of the output power of the amplifying circuit to the input terminal to complete the self-excited task. In essence, it plays the role of energy control. The function of the frequency selective network is to make the feedback signal through the positive feedback network, only the selected signal can make the circuit satisfy the self-oscillation condition, and the signal of other frequencies can be suppressed because it cannot satisfy the self-oscillation condition. The goal is to have the circuit produce a sinusoidal signal at a single frequency.
If the frequency selection network consists of R and C components, it is called RC sine wave oscillation circuit; if it is composed of L and C components, it is called LC sine wave oscillation circuit; if it is composed of quartz crystal, it is called quartz crystal oscillation circuit. The function of the amplitude stabilization circuit is to stabilize the amplitude of the oscillating signal. It can be implemented by a thermal element or other limiting circuit, or by using the nonlinearity of the amplifying circuit's own components. In order to better obtain stable equal amplitude oscillations, it is sometimes necessary to introduce a negative feedback network.
When analyzing the working principle of the oscillating circuit, first check whether the circuit has an amplifying circuit, a feedback network, a frequency selective network and a stable link, and then check whether the static working point of the amplifying circuit can ensure the normal operation of the amplifying circuit, and then analyze whether the circuit satisfies the self-excited The oscillation condition, that is, the phase balance condition and the amplitude balance condition.
The oscillation condition of the oscillation circuit includes two parts of an equilibrium condition and a start-up condition.
The equilibrium condition of the oscillating circuit is that the oscillating circuit maintains the condition of equal amplitude oscillation. The balance conditions of the oscillating circuit include an amplitude balance condition and a phase balance condition. The oscillating circuit is so low that it can output the signal without an external input AC signal because it uses its own positive feedback signal as the input signal.
Therefore, in order for the oscillating circuit to maintain equal amplitude oscillation, its amplitude and phase of the feedback signal Vf must be made identical to its net input signal Vid. The amplitude balance condition of the oscillating circuit is AF =1; the phase balance condition of the oscillating circuit is cpA + (pf=+2n, 7r(n=0, l, 2, 3--). In the formula, 妒A denotes a basic amplifying circuit The phase shift, 9f represents the phase shift of the positive feedback network. For an oscillating circuit, it must be full of the amplitude balance condition and phase balance condition of the oscillating circuit, and the oscillating circuit can maintain the equal amplitude oscillation.
When the oscillation circuit is just starting to work, a current disturbance occurs in the circuit at the moment when the power is turned on. These current disturbances may be sudden changes in current caused by the moment the power is turned on, or it may be a noise signal inside the triode or circuit. This current disturbance contains weak sinusoidal signals of various frequencies, which are the initial input signals of the oscillating circuit.
When the oscillation circuit starts to work, if AF "1" is satisfied, the sine wave signal with the same frequency as the frequency selective network can be amplified and fed back to the input terminal of the amplification circuit by the amplification and frequency selection of the oscillation circuit, while others The frequency signal is suppressed by the frequency selective network. In this way, the oscillation circuit can be oscillated from small to large after the power is turned on, until the AF=1, the oscillation amplitude is set. Therefore, AF"1 is called the starting condition of the oscillation circuit.
By using the nonlinearity of the triode or using negative feedback in the circuit, the oscillation circuit can be transitioned from AF 》1 to AF =1 to achieve stable amplitude.
If the sustain condition of the oscillating circuit and the start-up condition are combined, writing AF ≥ 1, this is the amplitude balance condition of the oscillating circuit. That is to say, it is necessary to ensure that the oscillation circuit can generate and maintain equal amplitude oscillation, and the vibration start condition must be satisfied while satisfying the maintenance condition. In summary, the oscillation condition of the oscillation circuit is AF≥1: (;PA +(pf=t:2n-rr(n =0,l,2,3--)o)
When designing an oscillating circuit, you must also pay attention to the following characteristics.
1 output level stability
Relative to time, temperature, output voltage level stability of the supply voltage.
2 oscillating waveform distortion
This is the distortion rate representation of the sine wave output. If it is a pure sine wave, the distortion rate becomes zero.
In the high-frequency oscillating circuit, in addition to the above characteristics, the frequency variable range and the oscillating frequency range at the time of design must be considered.
3 frequency stability
The quality of the oscillator circuit is determined by the frequency stability, which is an important characteristic of the oscillator. The change in frequency can be expressed by the following numerical values.
Frequency: Change over time
After the power is turned on, the frequency generated changes with the passage of time. In particular, the change is greatest at the time of the warm-up.
Frequency temperature coefficient
The frequency variation with respect to temperature change is expressed in ppm/°C.
Frequency: Power supply voltage change
The frequency variation when the power supply voltage changes is expressed in %/V.
We know that the oscillating circuit consists of four parts, namely, an amplifying circuit, a positive feedback network, a frequency selective network, and a amplitude stabilization circuit. When analyzing the working principle of the oscillating circuit, we should first check whether the various steps of the circuit are perfect. Secondly, we must check whether the static working point of the amplifying circuit is correct, whether the amplifying circuit can work normally, and then analyze whether the circuit satisfies the self-oscillation condition. After all aspects have been checked and confirmed, it is easier to understand the common principle of the oscillator circuit.
Function description
The socket is ordinary converter,with two output 5V2A power USB power supply at the same time,can be very convenient in use electrical appliances and recharge the equipment at the same time,such as digital products like Iphone Ipad,MP3,MP4 etc.The charge apply to full range of international AC output,no-load power consumption less than 0.3W,with short circuit,overload,over-voltage protection,can be convenient for your life and save more energy
Timer Control Time Adgustment
1.Press the power switch 1 time,the 1HOUR LED will light on.The Timer into ON mode,USB and control socket output ON .
2.Continuously press the power switch the LED light on,the Countdown mode and LED light on will cycle change from 1HR,2HR,4HR,6HR,8HR,10HR.
3.Choose you need countdown time mode,the mode LED will lighto on,start countdown until countdown time finish,the control output and USB change to OFF
4.Then the countdown is start,The Time indicate LED will from high to low auto change until Countdown finish off.
Failure analysis:
1.check whether the power supply connection is good
2.check whether the USB cable is loosen
Warning Note:
1.Use indoor and dry location ONLY
2.The load max does not exceed 15A 3600W
3.This product does not convert voltage please do not miss use DO NOT exceed the maximum loading of 3600 Watts 15A
4.Always have earth connection for safety reason
5.If in doubt please consult with a qualified electrician
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