Ⅰ. General introduction
Ⅱ. Different types of oscillator
Ⅲ. The working principle of an oscillator
Ⅳ. The function of oscillators
Ⅴ. Oscillator Selection Rules
Ⅵ. Oscillating Circuit Components
Ⅶ. Oscillator usage and precautions
Ⅷ. Applications of Oscillators
I. General introduction
An oscillator is an electronic circuit or device used to generate a periodic waveform signal. This waveform signal can be a sine wave, square wave, pulse wave or other forms of waveform, and its frequency and amplitude can be adjusted according to the design purpose. Computers, clocks, watches, radios, and metal detectors are among the many devices that use oscillators.
II. Different types of oscillator
There are many kinds of oscillators.
According to the oscillation feedback: positive feedback oscillator, and negative resistance oscillator. According to the oscillation frequency: low frequency oscillator, and high frequency oscillator. According to the oscillation waveform: sine wave oscillator, and non-sine wave oscillator.
Among them, the most important are harmonic oscillator and relaxation oscillator. It is mainly suitable for the oscillation cultivation of various liquid and solid compounds such as biology, biochemistry, cells and bacteria in various scientific research departments such as universities, medical treatment, petrochemical industry, sanitation and epidemic prevention, and environmental monitoring. Here we pick a few to illustrate.
1. Harmonic oscillator
A harmonic oscillator is a particle or system of particles or systems that move harmonically around an equilibrium position, such as an object with a mass vibrating on a spring. A harmonic oscillator produces a sinusoidal output in which the signal varies with time. There are two basic kinds of harmonic oscillators, RC (resistor/capacitor circuits) as well as LC (inductor capacitor circuits).
(1) RC circuits are well suited for lower frequencies.
(2) LC circuits are better suited for higher frequencies.
Both circuit types use an arrangement of complementary components to produce an oscillating output. As with any oscillator, energy is sent back into the system to make up for losses during processing.
2. Relaxation oscillator
A relaxation oscillator is a nonlinear electronic oscillator circuit used to generate non-sinusoidal outputs such as square waves, triangle waves, etc. A relaxation oscillator consists of a nonlinear element such as a transistor that periodically releases energy stored in a capacitor and inductor to produce an instantaneously varying output signal.
Relaxation oscillators are used to produce low frequency signals for applications such as blinking lights (turn signals) and electronic beepers and in voltage controlled oscillators (VCOs), inverters and switching power supplies, dual-slope analog to digital converters, and function generators.
3. Low frequency oscillator
An LFO is an oscillator that generates an AC signal with a frequency between 0.1 Hz and 10 Hz. This term is often used in audio synthesis because signals in this range are easily identified, so a good audio oscillator is important.
4. Sine wave Oscillator
A square wave generator is an oscillator that produces an output without any input. The input must be provided within zero seconds in the sense of no input, which means it must be a pulsed input. Since a square wave generator is rotated around its output frequency, it is called a "pulse" because of its use in digital signal processing and electronics. The frequency of a square wave generator is independent of the output voltage, which is why it is called an astable multivibrator or free running.
5. Linear oscillators
Linear oscillators are the most common form of electronic amplifiers (such as transistors or operational amplifiers). When the amplifier's power supply is applied, only noise appears at the output of the amplifier. This noise is passed to a narrow band filter (narrow band filter) so that a certain part of the frequency in the noise is filtered out and appears at the output of the filter. Since the output of the filter is connected to the input of the amplifier, the filtered signal is amplified by the amplifier and then goes into the filter circuit for filtering... and so on and so forth until the output signal is exactly what we want.
Ⅲ. The working principle of an oscillator
The frequency at which an oscillator works is usually determined by a quartz crystal. When a direct current is applied to such a crystal, it vibrates at a frequency that depends on its thickness, and on the manner in which it is cut from the original mineral rock. Some oscillators employ combinations of inductors, resistors, and capacitors to determine the frequency. However, the best stability (constancy of frequency) is obtained in oscillators that use quartz crystals.
In a computer, a specialized oscillator, called the clock, serves as a sort of pacemaker for the microprocessor. The clock frequency (or clock speed) is usually specified in megahertz (MHz), and is an important factor in determining the rate at which a computer can perform instructions.
The working principle of an oscillator can be roughly divided into the following stages:
1. Feedback circuit: An oscillator usually consists of an amplifier and a feedback loop. The amplifier is responsible for increasing the amplitude of the input signal, while the feedback loop returns a portion of the output signal to the input of the amplifier.
2. Phase condition: For the oscillator to produce a stable output signal, the feedback circuit must satisfy the phase condition. This means that the feedback signal must maintain a phase difference of 0 or an integer multiple of 360 degrees with respect to the input signal. Only when the phase condition is satisfied will the signal continue to amplify, resulting in oscillation.
3. Oscillation conditions: The oscillator gain and feedback must meet certain conditions so that the gain due to positive feedback compensates for system losses and attenuations, so that the output signal is continuously amplified.
4. Vibration initiation: Initially, the vibration source requires a certain amount of external energy to start vibrating. This may be due to initial excitation or other external signals. Once initiated, a positive feedback loop provides the energy needed to maintain the vibration.
5. Output Signal: The output signal generated by an oscillator is usually a periodic waveform whose frequency is determined by the design and component parameters of the oscillator. Common types of oscillators include sine wave oscillators, square wave oscillators, and pulse oscillators.
Ⅳ. The function of oscillators
In the field of electronics, the oscillator is a very important component that we cannot live without. Oscillators operate a digital clock. Oscillators are quartz crystals used to generate signals for timer that are used in clocks, wall clocks, table clocks, computers and telephones. A square wave is sent to the meter, resulting in a visible image. All digital devices have a different main type of clock that is used to synchronize all tasks performed by the microprocessor. It is used to synchronize all tasks performed by the microprocessor. This is a typical clock for both phones and computers. oscillator strength
Ⅴ. Oscillator Selection Rules
Oscillators play a vital role in many electronic products. We all know that electronic products are subject to various disturbances when they are working normally. Therefore, how to ensure the normal operation of electronic products is particularly important. Next, let's take a look at what are the oscillator selection rules?
(1) Model
When using the oscillator, be sure to see the model mark on the housing. The model number indicates multiple parameters of the oscillator, such as crystal frequency, phase, temperature range, etc. If not seen carefully, it can cause problems in the application. For example, when designing a product, the requirements of different products may not be considered, resulting in mismatched components, which eventually lead to problems in the application.
(2) Output method
When selecting an oscillator, consider the oscillator output type required by the circuit, which is generally divided into level output and differential output. In terms of level output, the most common type is CMOS. As far as differential output is concerned, commonly used differential output types are LVPECL (Low Voltage Positive Emitter Coupled Logic) and LVDS (Low Voltage Differential Signaling). Different output types cannot be changed at will, especially differential and common oscillators.
(3) Visual inspection
We need to check the appearance of the product to see if there are any defects on the surface of the product, such as scratches, dents, etc. At the same time, we should also pay attention to whether there are bubbles and impurities on the surface of the product, which are unqualified. When looking at product marks, we need to see whether the text marked on the product is clear and standardized, as well as the differences between different types of marks. When looking at the appearance of the product, if we find cracks, lack of glue, etc., it cannot be used.
(4) Frequency
We need to determine the frequency we need according to the actual product requirements. So the frequency is very important and cannot be changed casually. We can negotiate only after passing the qualification examination or professional examination. If the frequency required by the actual circuit is 5 MHZ, then we should not replace it with the same frequency. Otherwise, it will cause interference during signal transmission, resulting in signal distortion.
(5) Replacement
When replacing the oscillator, if the oscillator is damaged, generally we should replace it according to the original model. However, if after testing, the oscillator does not change, then it is best to consider changing to a different model or type of oscillator. oscillator indicator
Ⅵ. Oscillating Circuit Components
A circuit composed of an oscillator is called an oscillator circuit.
(1) Amplifying circuit
The general oscillation circuit is composed of four parts: amplifier circuit, positive feedback network, frequency selection network and amplitude stabilization circuit. In the oscillating circuit, in order to satisfy the condition of amplitude balance, we must use an amplifying circuit. Because during the oscillation process, there will inevitably be energy loss, which will lead to oscillation attenuation. Through the amplifying circuit, we can control the power supply to continuously provide energy to the oscillating system to maintain constant amplitude oscillation. Therefore, the amplifying circuit is essentially a transducer. It plays the role of supplementing energy loss.
(2) Positive feedback network
Positive feedback network is one of the necessary conditions to meet the phase balance condition. It returns part or all of the output power of the amplifying circuit to the input terminal to complete the self-excitation task. In essence, it acts as energy control. The function of the frequency selection network is to make the circuit satisfy the condition of self-excited oscillation among the feedback signals passing through the positive feedback network. For signals of other frequencies, they are suppressed because they cannot meet the self-oscillation conditions. The purpose is to make the circuit generate a single-frequency sine wave signal.
(3) Frequency selection network and amplitude stabilization circuit
If the frequency selection network is composed 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. We know that the amplitude of the oscillating signal is constantly changing, but it is relatively stable within a certain range. In order to keep the amplitude of the oscillating signal stable, the oscillator can be implemented not only by using a thermal element or other limiting circuit, but also by using the nonlinearity of the amplifier circuit's own components. In order to obtain stable equal-amplitude oscillations, we also need to introduce a negative feedback network.
Ⅶ. Oscillator usage and precautions
Usage：
1. Put it into the test bottle and keep it balanced. If it is a dual-function model, set the oscillation mode.
2. Turn on the power and set the timing according to the scale on the surface of the machine. If you need to work for a long time, turn the timer to the "normal open" position.
3. Turn on the power switch and set the constant temperature:
(1) Put the small control switch in the "Setting" section. At this time, the temperature displayed on the display screen is the set temperature. Adjust the knob to set the temperature required for your work. (The working temperature you set should be higher than the ambient temperature. At this time, the machine starts to heat up and the yellow indicator light is on, otherwise the machine will not work)
(2) Put the small switch of the control part on the "measurement" end, at this time the temperature displayed on the display is the actual temperature of the air in the test chamber, and as the temperature in the chamber changes, the displayed number will also change accordingly. oscillator symbol
(3) When the heating reaches the temperature you need, the heating will stop automatically, and the green indicator light will be on; when the heat in the test chamber dissipates and is lower than the temperature you set, a new round of heating will start again.
4. Turn on the oscillation device:
(1) Turn on the oscillation switch on the control panel, and the indicator light will be on.
(2) Adjust the oscillation speed knob to the desired oscillation frequency.
5. Cut off the power supply after work, and set the speed control knob and temperature control knob to the lowest point.
6. Clean the machine.
Precautions:
1. It is strictly forbidden for objects to hit the machine.
2. Make sure the power supply is cut off before replacing the fuse.
3. It is strictly forbidden to move the machine during normal working hours.
4. Children are strictly prohibited from approaching the machine to prevent accidents.
5. The power socket provided by the user should have good grounding measures.
6. Please clean the machine after use, and no water droplets or dirt residues can be left.
7. The appliance should be placed on a relatively firm work surface, and the environment should be clean and tidy with good ventilation.
Ⅷ. Applications of Oscillators
Oscillators have a wide range of applications in modern electronic equipment. Common applications include:
1. Quartz watches (using crystal oscillators)
2. For alarms and buzzers
3. For operating decorative lights (e.g. dancing lights)
4. For generating clock pulses for microprocessors and micro-controllers
5. For inverters, stun guns, ultrasounds and metal detectors
6. Used in various audio systems and video systems
7. Used in a variety of television, radio, and other communications equipment
8. Used in computers, metal detectors, stun guns, inverters, ultrasonic and RF applications
