(1) Unidirectional conductive qualities. The diode features a one-way conductive house, only allowing existing to flow from the optimistic electrode for the adverse electrode, but not enabling present to flow in the damaging electrode to the good electrode. In accordance with different manufacturing supplies, it truly is divided into germanium diodes and silicon diodes. The germanium diodes and silicon diodes have various forward tube voltage drops throughout forward conduction. For any silicon germanium diode, when the applied forward voltage is higher than the forward tube voltage drop, the diode conducts. The forward voltage with the germanium diode is about 0.3V. When the forward voltage with the silicon diode is greater than 0.7V, the silicon diode is turned on. Furthermore, at the exact same temperature, the reverse leakage existing of silicon diodes is a great deal smaller sized than that of germanium diodes.
(2) The principle parameters in the diode.
① Maximum rectified current IFM: refers to the maximum average present permitted to pass forward through the PN junction. The actual working current in use really should be significantly less than IFM, otherwise the diode will likely be damaged.
②Reverse current Ico: refers towards the current by means of the diode under the reverse voltage specified on the diode. Silicon tubes are 1μA or smaller sized, and germanium tubes are about a few hundred microamperes. The smaller the reverse existing in use, the far better.
③ Maximum reverse voltage Urm: refers for the maximum reverse voltage applied across the diode without having causing breakdown from the PN junction. Diodes with URM greater than two occasions the actual operating voltage really should be selected for the duration of use.
④Maximum functioning frequency fm: refers to the highest frequency of your diode to ensure its very good operating characteristics, referred to as the highest working frequency. It ought to be at least higher than 2 occasions the actual operating frequency with the circuit.
recover deleted Video from SanDisk SD Card ) Measurement of diode
A multimeter is often applied to measure the forward and reverse conduction qualities from the crystal diode. When measuring the diode, it should be noted that the red test lead with the ordinary multimeter is connected to the unfavorable electrode on the battery, along with the black test lead is connected for the good electrode of your battery. It can also be said that the black test pen could be the good pole of your energy supply along with the red test pen is the unfavorable pole on the power supply, as shown in Figure 1-25.
The polarity of the diode is generally marked by the colour ring around the side in the element. The lead-out finish of the colour ring is definitely the negative pole or N pole, and the side without having the color ring is definitely the optimistic pole or P pole. It can be measured with R × 100Ω and R × 1kΩ of multimeter. Based on the unidirectional conduction characteristics on the diode, that's, the forward resistance is compact and also the reverse resistance is substantial, use the test pen to connect towards the two poles in the diode respectively. If the red test pen is connected to the good pole (P pole) of your diode, the black test pen is connected towards the damaging pole (N pole) The indicated resistance needs to be greater than 100kΩ; when the black test lead is connected to the anode (P pole) of your diode along with the red test lead is connected for the damaging pole (N pole), the resistance need to be much less than 1.5kΩ, then the end with the black test pen would be the anode on the diode (P pole). In the event the reverse resistance of the diode along with the diode is small, it indicates that the diode is short-circuited; if the forward resistance is big, it indicates that the diode is internally disconnected. Each cases indicate that the diode is damaged and cannot be made use of, as shown in Figure 1-23.
six. Triode
The most recent regular of crystal transistors is named transistors, which are the core components of several electronic devices. They're also inseparable from a variety of electronic circuits. Transistors can play a range of roles inside the circuit, including amplification, oscillation, and switching.
1) The structure of your transistor
The transistor is produced of two PN junctions made of semiconductor material. Its 3 electrodes are connected to the 3 locations inside the tube-the launch location, the base location, and also the collector area. There are two varieties of transistors: PNP type and NPN type. The internal structure and circuit symbols are shown in Figure 1-24.
Figure 1-24 (a) shows a schematic diagram in the structure of an NPN transistor, which is composed of three semiconductors, forming two PN junctions, namely a collector junction and an emitter junction, which results in a total of three electrodes, namely a collector in addition to a base And emitter. The working existing inside the tube consists of collector existing Ic, base current IB, and emitter existing IE. Ic and 1B merge and flow out from the emitter. The path from the emitter arrow within the circuit symbol visually indicates the direction of present flow. The above letters representing every pole may also be represented by c, b, and e. Ie = Ib + Ic, since Ib is compact (neglected), Ic≈Ie.
Figure 1-24 (b) is actually a schematic diagram of the structure on the PNP variety transistor. The distinction from the NPN sort is that the arrangement direction of the P and N form semiconductors is distinctive, plus the other is essentially the exact same. The path of the current is from the emitter towards the tube, and each the base existing and the collector current flow from the tube. This could also be noticed from the path of the emitter arrow inside the PNP sort tube circuit symbol.
2) Forms of transistors
There are several sorts of triodes: based on the material, you will find germanium triodes, silicon triodes, etc .; in line with the polarity, they can be divided into NPN triodes and PNP triodes; based on different makes use of, they could be divided into high-power triodes, low-power triodes, High-frequency triode, low-frequency triode, photoelectric triode; in accordance with various purposes, it may be divided into ordinary triode, resistance triode, damped triode, Darlington triode, photosensitive triode, and so on .; in accordance with distinctive packaging components, it may be divided into metal Packaged transistors, plastic packaged transistors, glass packaged (abbreviated glass packaged) transistors, surface packaged (chip) transistors and ceramic packaged transistors, etc. The shape in the triode is shown in Figure 1-25.
Below normal situations, the maximum collector allowed to dissipate energy Computer, the triode beneath 1W is named a low-power triode; the triode with a characteristic frequency beneath 3MHz is named a low-frequency triode; the triode with a characteristic frequency above 3MHz and below 30MHz is called an intermediate frequency Transistors; transistors with characteristic frequency greater than 30MHz are called high-frequency transistors; transistors with characteristic frequency higher than 300MHz are referred to as UHF transistors. UHF transistors are also named microwave transistors, whose frequency qualities are generally larger than 500MHz, and are primarily employed for tv and radar , Navigation, communications as well as other fields to deal with smaller microwave signals (frequency above 300MHz).
High-frequency medium and high-power transistors are generally applied in video amplifying circuits, pre-amplifying circuits, complementary driving circuits, high-voltage switching circuits and line driving circuits.
Medium and low frequency low power transistors are primarily utilized in low frequency amplification and power amplification circuits with decrease operating frequency and energy under 1W.
Medium and low frequency high energy triodes are frequently applied in household appliances for example televisions and audios, as energy adjustment tubes, switch tubes, field output tubes, line output tubes, energy output tubes or applied in automotive electronic ignition circuits, inverters, emergency power supplies (UPS) and other method circuits.
3) Measurement of transistor
(1) Discrimination with the base in the transistor. The triode is composed of two PN junctions with opposite directions. According to the properties of compact forward resistance and huge reverse resistance in the PN junction, a multimeter is used to test R × 100 or R × 1kΩ. It may be assumed that any on the pins would be the 'base', connect the 'base' with a red test lead, plus the black test lead touches the other two pins, if the measured values are both low resistance; then connect the black test result in the 'base' ', The red test lead is connected towards the other two pins. When the readings are all high-resistance, the above-mentioned assumed' base 'is right, and it can be a PNP transistor, as shown in Figure 1-26.
In case you use the black test result in connect the hypothetical 'base', the red test lead touches the other two pins respectively, when the measured values are all low resistance. Then connect the red test result in the 'base' plus the black test lead to the other two pins. When the readings are all higher resistance, the assumed 'base' may be the base with the NPN transistor, and this tube will be the NPN transistor. As shown in Figure 1-27.
If a black or red test lead is applied to connect the hypothetical 'base', plus the remaining test leads touch the other two pins respectively, the measured result is usually a low resistance worth as well as a high resistance worth, then the original hypothesis 'base' It can be incorrect, it really is necessary to re-assume a 'base' and test once again until the needs are met.
(two) Judgement of emitter and collector. For the NPN sort triode, the strategy of discrimination is as follows: having a multimeter R × 1k block, first connect the black test cause the assumed “collector” and the red test lead to the “emitter”. Put some water on your finger, hold the black test lead and also the 'collector', and after that touch the base (the two electrodes cannot touch collectively), as shown in Figure 1-28, that is certainly, add a optimistic for the base with the triode by way of the resistance of your hand Bias to make the transistor conductive. Observe the deflection in the hands at this time and record the resistance indicated by the hands. Then assume that the other pin will be the 'collector', repeat the above test, and record the angle with the needle deflection as well as the resistance value indicated by the needle. Comparing the resistance worth indicated by the two needle deflections twice, the time when the needle deflection angle is significant plus the indicated resistance worth is tiny, it is actually assumed to become correct, that's, the collector is connected to the black meter pen this time.
If it really is a PNP variety triode, just connect the red test cause the assumed 'collector', touch your finger with water, pinch the black test lead and 'emitter', and after that touch the base (the two electrodes can not touch together), as outlined by the above system Just test, as shown in Figure 1-29.
Speedy identification: Considering that a lot of the present triodes are silicon tubes, the R × 10k block might be employed (the battery inside the multimeter is 15V). The red and black test leads straight measure the c and e poles, good and negative twice, and one of the hands swings Hundreds of a large number of euros). If each swings, the one particular together with the bigger swing shall prevail. The NPN tube is connected towards the c-pole with the red pen, as well as the black pen is connected towards the e-pole. The red pen from the PNP tube is connected to the e pole, and also the black pen is connected for the c pole (note: this process is only applicable to silicon tubes, contrary towards the above technique, and this system is also the best solution to distinguish the c and e poles inside the photocoupler).
(3) Measurement of DC amplification issue hFE. Initial turn the multimeter rotary switch towards the AM position from the transistor adjustment, short the black test rod, adjust the ohm potentiometer, align the pointer with the 300hee scale line, then turn the switch to the hFE position, insert the transistor pins to become tested in to the transistor test Within the e, d, c tube seat from the seat. The value shown by the pointer deflection could be the DC magnification of your transistor, that's, the B worth. The N-type transistor should be inserted in to the N-type tube hole, as well as the P-type transistor ought to be inserted into the P-type tube hole.
7. Field impact transistor
1) Structure and functionality characteristics of VM0S field impact transistor
VMOS field effect transistor can be a energy variety field impact transistor, which can be called V-groove MOs field effect transistor, abbreviated as VMOS tube. VMOS tube has three electrodes, namely gate G, drain D and supply S. You will discover two drawing approaches for circuit symbols, a single is built-in protection diode kind, and the other is built-in protection diode variety, as shown in Figure 1-30. The characteristic of VMOS tube is the fact that it has V-shaped groove and has vertical conductivity. The drain D is drawn from the back on the chip, so the drain present ID throughout operation doesn't flow horizontally along the surface, but starts from the heavily doped N + area (supply S) and flows through the channel forming an angle with the surface To the lightly doped N-drift area, and then to the drain D vertically. Hence, folks frequently refer to this kind of semiconductor device with v-groove structure and vertical conductivity sort as V-MOSFET (vertical conductivity metal-oxide-semiconductor field impact transistor). VMOS tube has the characteristics of higher input impedance, low drive existing, high withstand voltage (maximum withstand voltage of 1200V), huge operating current (1.5A ~ 100A), significant output power (1W ~ 250W), superior cross-conductivity, quick switching speed, and so forth. .
2) Field effect transistor detection
The three poles on the power MOSFET: G, S, and D are insulated from one another, and you will discover two back-to-back diodes in between D and S, so it is simple to judge their goodness with a pointer-type three-meter (R × 1k block) negative. Furthermore, a diode is connected in parallel amongst the drain and source from the energy MOSFET, and the cathode and anode in the diode may be measured during the test. The process of determining the top quality of your N tube might be described as an example beneath.
Set the multimeter to 1kΩ, connect the red test pen to S, the black test pen to G, the red test pen to G, the black test pen to S, plus the pointer does not move (the resistance is infinite); then make use of the red test pen to connect D, the black test pen to G and red Connect the test bring about G as well as the black test result in D, and the pointer is not going to move. That is for the reason that t here is an insulating layer of silicon dioxide amongst G and D and S, so the resistance is infinite. Connect the black test result in S and G, the red test cause D, the pointer turns to about 10kΩ, which measures the forward resistance value on the internal diode (protection diode); the black test cause D, the red test cause S and G, the pointer does not That is the internal diode reverse resistance as well as the resistance value when there's no conductive channel involving D and S. This N-channel power MOSFET is good.
When measuring the resistance in between D and S, it can be necessary to connect S and G with each other, mainly because when measuring the low threshold voltage power MOSFET, its VGS (Th) = 0.45V ~ 1V. When measuring the resistance involving G and S, because t here is a voltage of 1.5V in the resistance meter, a voltage of 1.5V is added between the G and S poles, which causes charges to become generated on the two plates along with a conductive channel is generated. Considering that there is no discharge path, this charge can't be discharged, so in the event the resistance between G and S will not be connected just after the resistance in between G and S is measured, the resistance between D and S will probably be measured to be little ( Since the 1.5V battery voltage within the table is applied for the D, S pole, G, S plus the induced charge has formed a conductive channel, so the resistance is measured to become smaller, plus the G and S are connected with each other to form a discharge circuit , No conduction condition).
In the event the resistance between G and S or in between G and D is modest when measured by the above technique, or when G and S are connected to the red test lead and D is connected for the black test lead, the resistance just isn't infinite (tens of a huge number of ohms or numerous a huge number of ohms), Then this N tube has been damaged. When the measurement among D and S (red and black swap measurement) is infinite, the diode is broken. The technique of measuring P tube is the similar as that of measuring N tube, but the polarity is opposite.
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