Basic Electronic concepts

Basic Electronic concepts
[Current] [voltage] [resistance] [Ohm's law] [power supply] [load] [circuit] [potential force]
[Cycle] [frequency rate] [capacitance] [capacitance resistance] [inductance] [inductance resistance] [impedance] [phase] [Phase Difference]

Electric stream:The direct movement of charge is called current. In the circuit, the current is often expressed as I. The current is divided into two types: DC and AC. The size and direction of the current do not change with time. The current size and direction change over time. The unit of current is security (A), which is also commonly used as the unit of MS or UA. 1A = 1000mA, 1mA = 1000ua.
Current can be measured using an ampersand. When measuring, concatenate the current meter in the circuit, and select the current meter pointer close to the full deflection range. This prevents the current from being too large and damaging the current meter.

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Electric pressure:The reason why the river can flow is that there is a water gap; the reason why the charge can flow is that there is a potential difference. The potential difference is the voltage. Voltage is the reason for current formation. In the circuit, the voltage is commonly displayed as a u table. The unit of voltage is V, which is also commonly used as unit of MV or UV. 1 V = 1000mV, 1mV = 1000uv.
Voltage can be measured with a voltmeter. During measurement, the voltmeter is connected in parallel to the circuit, and the voltmeter pointer should be near the full deflection range. If the voltage on the circuit cannot be estimated, a large range should be used first, and a proper range should be used after rough measurement. This prevents damage to the voltmeter due to excessive voltage.

Electrical Resistance:The part in the circuit that hinders the passage of current and causes energy consumption is called resistance. Resistance is commonly expressed by R. The unit of resistance is Euro (Ω), which is also commonly used as the unit of kilobytes (kΩ) or megabits (MΩ. 1 k Ω = 1000 Ω, 1 m Ω = 1000000 Ω. The resistance of a conductor is determined by the material, cross-sectional area, and length of the conductor.
The resistance can be measured in the Ohm of a multimeter. During measurement, select an ohm which is close to half of the deflection of the electric meter pointer. If the resistor is in the circuit, you need to burn one of the resistors before measuring.

Ohm's Law:The current I in the conductor is proportional to the voltage U at both ends of the conductor, and is inversely proportional to the resistance R of the conductor, that is

This rule is called Ohm's law. If you know two of the three quantities of voltage, current, and resistance, you can find the third quantity according to Ohm's law, that is

In the AC circuit, Ohm's law is also true, but the resistance R should be changed to the impedance Z, that is

Power Source:Other forms of devices that can be converted into electrical energy are called power supplies. A generator can convert mechanical energy into electrical energy, while a Dry Battery can convert chemical energy into electrical energy. Generators and dry batteries are called power supplies. Transformer and rectifier are used to convert AC power into DC power. An electronic device that provides signals is called a signal source. The transistor can zoom in the signal sent in front and transmit the enlarged signal to the circuit below. The transistor can also be seen as a signal source for the circuit behind it. Rectifying power supply and signal source are also called power supply.

Negative load:A device that converts electric energy into other forms of energy is called a load. A motor can convert electric energy into mechanical energy, a resistor can convert electric energy into thermal energy, a bulb can convert electric energy into thermal energy and optical energy, and a speaker can convert electric energy into acoustic energy. Electric motors, resistors, bulbs, and speakers are called loads. The transistor can also be considered as a load for the signal source.

Electricity:The current flow is called a circuit. The simplest circuit consists of power supply, load, wires, switches, and other components, as shown in 1. Circuit connectivity is called a path. Only through the circuit can the current pass through. A circuit disconnection is called an open circuit or an open circuit. The two ends of a part of the circuit are directly connected, so that the voltage of this part is changed to zero, which is called a short circuit.

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EMR:EMF is a physical quantity that reflects the power supply's ability to convert other forms of energy into electric energy. EMFs generate voltage at both ends of the power supply. In the circuit, the potential force is often expressed as delta. The unit of the EMR is the same as that of the voltage.
The EMF of the power supply can be measured with a voltmeter. During the measurement, the power supply should not be connected to the circuit. Use a voltmeter to measure the voltage at both ends of the power supply. The obtained voltage value can be regarded as an EMR equal to the power supply. If the power supply is connected to the circuit (Figure 2), the voltage at both ends of the power supply measured by the voltmeter will be less than the EMR of the power supply. This is because the power supply has internal resistance. In a closed circuit, the current falls through the internal resistance R and the external resistance R. The EMF delta of the power supply is equal to the sum of the inner voltage u r and the outer voltage u r, that is, Delta = u r + u r. Strictly speaking, even if the power supply is not connected to the circuit, a voltage meter is used to measure the voltage at both ends of the power supply. The voltage meter is an external circuit, and the voltage measured is smaller than the potential force. However, because the internal resistance of the voltmeter is very large, the internal resistance of the power supply is very small, and the internal voltage can be ignored. Therefore, the voltage at both ends of the power supply measured by the voltmeter can be considered as equal to the power source EMR.

When a Dry Battery is used up, the voltage at both ends of the battery is measured. Sometimes it is still relatively high, but the load (radio, recorder, etc.) cannot work normally after the circuit is connected. This is because the internal resistance of the battery increases, even greater than the load resistance, but still smaller than the internal resistance of the voltmeter. When the voltage at both ends of the battery is measured by a voltmeter, the voltage obtained by the resistor in the battery is not large, so the voltage measured by the voltmeter is still relatively high. However, when the battery access circuit is used, the internal voltage of the battery resistance increases, and the voltage of the load resistance decreases. Therefore, the load cannot work properly. To determine whether the old battery can be used, the voltage at both ends of the battery should be measured at load. The voltage difference between the two ends of the power supply measured in the case of poor performance, load and no load is large, also because the internal resistance of the power supply is large.

Weekly:The time required to complete a complete change of alternating current is called a cycle, which is usually represented by T. The unit of cycle is second (s), also commonly used Millisecond (MS) or microsecond (US) Do unit. 1 S = 1000 ms, 1 S = 000000us.

FrequencyThe frequency of alternating current periodic changes within one second is called frequency, which is commonly expressed by F. The unit of frequency is Hz, which is also commonly used as the unit of kHz or MHz. 1 kHz = 1000Hz, 1 MHz = 1000000Hz. The alternating current frequency f is the reciprocal of the cycle T, that is

Electric Capacity:Capacitance is a physical quantity used to measure the charge storage capability of a conductor. When a certain voltage is added to two insulated conductors, they store a certain amount of electricity. One conductor stores a positive charge, and the other conductor stores a negative charge of the same size. The higher the voltage, the more power is stored. The storage power is proportional to the added voltage, and their ratio is called capacitance. If the voltage is displayed in the u table, the power is expressed in Q, And the capacitance is expressed in C, then

The unit of capacitance is method (f). Also, Micromethod (UF) or Micromethod (PF) is often used as the unit. 1f = 10 6 UF, 1f = 10 12 PF.
The capacitance can be measured by a capacitance tester or roughly estimated by the Ohm of a ten-thousand-meter. The two red and black table pens touch the two feet of the capacitor respectively, and the battery in the Ohm table will charge the capacitor, the pointer deflection, the charge is complete, and the pointer returns to zero. Change the red and black table pens, and the capacitor will be recharged after discharge. The larger the capacitance, the larger the pointer deflection. Compare the deflection between the tested capacitor and the known capacitor to roughly estimate the value of the tested capacitor. In general electronic circuits, in addition to the tuning loop and other capacitors that require more accurate capacity, the most frequently used capacitors, such as isolating, bypassing, and filtering are used, no capacity-accurate capacitors are required. Therefore, it is of practical significance to roughly estimate the capacitance value using the Ohm file. However, the Ohm file of a common universal electric meter can only be used to estimate the capacitance with a large value. For a capacitance with a small value, the Ohm file of a universal electric meter must be used to estimate the value, the capacitance smaller than dozens of micro methods had to be measured using a capacitance tester.

Anti-DDoS:The AC can pass through the capacitor, but the capacitor still hinders the AC. The blocking effect of capacitance on AC power is called capacity resistance. A large quantity of capacitors, the AC is easy to pass through the capacitor, indicating that the capacitor is large, the obstruction of the capacitor is small; the AC frequency is high, the AC is easy to pass through the capacitor, indicating that the frequency is high, and the obstruction of the capacitor is small. Experiments show that the capacity and frequency are inversely proportional to the electrical capacity. If the capacity is expressed in x C, the capacitance is expressed in C, and the frequency is expressed in F, then

The anti-DDOS service is in Europe. Knowing the AC frequency f and capacitor C, you can use the formula to calculate the capacity.

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Electrical sense:Inductance is a physical quantity used to measure the electromagnetic induction capability of the coil. When a coil enters the current, the magnetic field will be generated around the coil, And the coil will have the magnetic flux passed. The larger the power supply of the incoming coil, the stronger the magnetic field and the larger the magnetic flux through the coil. Experiments show that the magnetic flux of the coil is proportional to the incoming current, and their ratio is called the self-sensing coefficient or inductance. If the magnetic flux of the coil is expressed by PHI, the current is expressed by I, and the inductance is expressed by L, then

The unit of inductance is Heng (h), which is also commonly used as the unit of Min Heng (MH) or micro Heng (Uh. 1 H = 1000mh, 1 H = 000000uh.

Anti-DDoS:Alternating current can also pass through the coil, but the inductance of the coil has a blocking effect on alternating current. This blocking is called inductive resistance. High inductance, difficult to pass through the AC coil, it indicates that the inductance is blocked, the AC frequency is high, and the AC is difficult to pass through the coil, it indicates that the frequency is high, and the obstruction of the inductance is also great. Experiments show that the inductance is proportional to the inductance and the frequency. If the inductance is expressed by x l, the inductance is expressed by L, and the frequency is expressed by F, then

The anti-DDOS service is in Europe. Knowing the alternating current frequency F and the inductance L of the coil, you can use the formula to calculate the inductance.

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Resistance:In a circuit with resistance, inductance, and capacitance, the obstruction to AC power is called impedance. Impedance is commonly expressed by Z. The impedance is composed of three parts: resistance, inductance, and capacitance. If the three are connected in series and the AC frequency F, resistance R, inductance L and capacitor C are known, then the impedance of the Series Circuit

The impedance unit is Euro.
For a specific circuit, the impedance does not change, but changes with the frequency. In the resistor, inductor, and capacitor series circuit, the impedance of the circuit is generally larger than that of the resistor. That is, the impedance is reduced to the minimum value. In the inductor and Capacitor parallel circuit, the impedance increases to the maximum value during resonance, which is opposite to the series circuit.

Phase:Phase is a physical quantity that reflects the state of alternating current at any time. The size and direction of alternating current vary with time. For example, the sine alternating current formula is I = isin2 π ft. I is the instantaneous value of AC current, I is the maximum value of AC current, F is the frequency of AC, t is the time. With the passage of time, the AC current can be changed from zero to the maximum value, from the maximum value to zero, and from zero to the maximum value of the negative, from the maximum value of the negative to zero, as shown in 3. In trigonometric functions, 2 π ft is equivalent to angle. It reflects the state of alternating current at any time, whether it is increasing or decreasing, whether it is positive or negative, and so on. Therefore, 2 π ft is called a phase or a phase.

Figure 3
If t is equal to zero and I is not equal to zero, the formula should be changed to I = isin (2 π ft + psi), as shown in 3 B. Then 2 π ft + PSI is called the phase, and PSI is called the initial phase or the initial phase.

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Phase Difference: the difference between the two AC phases with the same frequency is called a phase difference or a phase difference. The two alternating current with the same frequency can be two alternating current, two alternating voltages, two alternating EMFs, or two of the three quantities.
for example, to study the phase difference between the AC voltage added to the circuit and the AC current through the circuit. If the circuit is a pure resistor, the phase difference between the AC voltage and current is equal to zero. That is to say, when the AC voltage is equal to zero, the AC current is also equal to zero. When the AC voltage changes to the maximum value, the AC current also changes to the maximum value. This is called the same phase or the same phase. If the circuit contains inductance and capacitance, the phase difference between the AC voltage and the AC current is generally not equal to zero, that is, it is generally different phases, or the voltage is ahead of the current, or the current is ahead of the voltage.
the phase difference between the AC voltage added to the transistor amplifier base and the AC voltage output from the Collector is exactly 180 °. This is called reverse phase or reverse phase.