【 Weak current College 】 Crystal diode consists of a variety of rectifier circuit 】

Power supply AC user is, and various wireless devices require DC power. Rectification is the process of alternating current into direct current. Use a one-way devices electrically conductive characteristics, you can put the orientation and size alternating current into direct current. The following describes the use of Crystal diode rectifier circuit consisting of various kinds.
1. half wave rectifier circuit diagram 1, half-wave rectifier circuit diagram 1, is the most simple rectifier circuit.　　It consists of a power transformer, rectifier diode B and D, load resistance Rfz. The AC voltage transformer (220 volt) into the required alternating voltage e2, D and AC DC for pulsation. transformation The following figure 5-2 waveform diagram looks at how the rectifier diode. Figure 2 half-wave rectifier waveform voltage transformer cut-e2, is a direction and size over time, sine wave voltage waveform as in Figure 2 (a) below. 0 ~ K hours, e2 is half week that is at the bottom of the top as the transformer is negative. This diode forward voltage withstand surface conduction, e2 through its combined load resistance Rfz, π π ~ 2 hours and a half weeks e2 is negative, the transformer secondary lower is positive, the top is negative. Then D inherit the reverse voltage, not breakover, Rfz, no voltage on. In π π ~ 2 hours, 0 to π time consuming, and in 3-4 π π, and repeat π π ~ 2 hours of ... This repeated, AC was negative half week "cut", only being half week through Rfz, Rfz won a single right (on the next negative) voltage, as in Figure 2 (b) below, the purpose of achieving a rectifier, however, the load voltage Usc. The size of the load current also change over time, therefore, typically refer to it as a pulsating DC. This drop in the lower half-week, week rectifier method, called half-wave rectifier. It is not difficult to see that the whole half wave is to "sacrifice" half the price and exchange for rectification of the current utilization is low (calculation shows that the half-wave rectifier voltage throughout the period, on average, the load on the DC voltage Usc = 0.45e2) therefore commonly used in high-voltage, low current, but in general the radio device is rarely used. 2. full-wave rectification circuit if the structure of the rectifier circuit, made some adjustments, you can get a full use of the power of full-wave rectification circuit. Figure 3 is a full-wave rectification circuit's electrical schematic. Figure 3 full-wave rectification circuit full-wave rectification circuit, can be thought of as consisting of two half-wave rectifier combinations. The transformer secondary windings need leads to a tap, the group split into two symmetric coil winding, which leads to the same size but the polar opposite of two voltage e2a, e2b, constitute e2a, D1, D2 with e2b, Rfz, Rfz, two power circuit. Full-wave rectification circuit works, shown in Figure 4 description of waveform diagram. In the 0 to π, e2a on Dl for forward voltage, D1 breakover, Rfz get on down negative voltage; e2b on D2 D2 for reverse voltage, not conduction (see Figure 4 (b). In π π-2, D2 e2b on the forward voltage, D2 breakover, won the Rfz remains on as negative voltage; e2a on D1 to reverse voltage, not on-D1 (see Figure 4 (C).

So repeatedly, because both rectifier D1, D2 take turns conducting, load resistance Rfz on in the positive and negative effects of two and a half weeks, has the same direction of current adoption, as in Figure 4 (b) as shown, so called full-wave rectification, full-wave rectification not only leverage is half a week, but also subtly use negative half week, thereby greatly improving the efficiency of the rectifier (Usc = 0.9e2, more than half wave rectifier is doubled). Figure 3 shows the full wave the whole filter circuit, there is a need to make both ends of transformer balanced secondary Centre tap, bring this to the making, a lot of trouble. In addition, this circuit, each rectifier diode afford maximum reverse voltagetransformer secondary voltage, maximum of two times, and therefore need to be able to withstand the higher voltage diode. Third, the bridge rectifier circuit diagram 5 (a) for bridge rectifier circuit, (b) the figure for the simplified method.

Figure 5 (a) for bridge rectifier circuit diagram
Figure 5 (b) the figure for its simplified method
Bridge rectifier circuit is the most used a rectifier circuit. This circuit, as long as the additional two diodes port connection to "bridge"-type structure, it has a full-wave rectification circuit, whereas at the same time, to a certain extent, overcome its weaknesses. Figure 6 bridge rectifier circuit works bridge rectifier circuit works as follows: e2 is half week, D1, D3, direction, voltage, Dl; on D2 D3 breakover, D4 plus reverse voltage cutoff, D2, D4. Circuit composition e2, Dl, Rfz, D3 power circuit, in the form on the Rfz, as negative half-wave voltage, the entire wash e2 is negative half week, D2, D4 plus forward voltage, D2, D1, D4 breakover, D3 and reverse voltage, D1, D3. Circuit composition e2, D2 Rfz, D4 power circuit, the same formation on the Rfz as negative on the other half wave rectifier voltage. The working state, respectively, as in Figure 6 (A) (B) below. So repeat indefinitely, resulting in the Rfz, will get a full-wave rectifier voltage. The wave figure and full-wave rectification wave figure is the same. From Figure 6 also is not difficult to see, and bridge circuits each diode reverse voltage equal to withstand the transformer secondary voltage, maximum value, full wave, half the entire wash circuit small! 4 Rectifier elements for the choice and application of it's important to note that as a rectifier diode, according to the different way of rectifying and load size to choose. If you select inappropriate or unsafe, or even fire tubes; or overkilled wastage. Table 1 parameters are available when you reference a diode. "In addition, the high voltage or high-current, if you do not have to bear high voltage or setting large capacitance of Rectifier elements, you can put together in series or parallel connection diodeUse. Figure 7 using a diode in parallel as shown in Figure 7 shows the diode parallel situation: two diodes connected in parallel, each sharing circuit total current half mouth three diodes connected in parallel, each share of one third of the total current in the circuit. In short, there are few diodes connected in parallel, the flowing through each diode current is equal to a fraction of the total current. However, when the actual application in parallel ", since the diode is not completely consistent, cannot be adopted by the current, the branch will make a pipe's overburdened and burned. So in each diode series a resistance on the same small resistor for current shunt diode through nearly unanimously. This current resistance R General selection zero several Europe-dozens of Europe resistor. Current increases, the more small R should be chosen. Figure 8 using diode-line as shown in Figure 8 the diodes in series. Apparently under ideal conditions, there are a few tubes in series, each pipe bear reverse voltage should be equal to a fraction of the total voltage. But because each diode reverse resistance, will result in voltage distribution: internal resistance of diode, likely due to the voltage by the breakdown and the resulting ripple effects, punctured by the diode. In diodes in parallel resistance R on, you can make the voltage distribution uniformity. Pressure resistance to get resistance than diode reverse resistance values of resistors, various small resistors of resistance to equality.