[introduction]Circuit is used individual double knife double cast (DPDT) switch will control polarity of electric machinery connective. Pass switch contact, the power source of electric machinery terminal can invert, electric machinery also can invert direction. The 2nd circuit a little a few more complex, use 4 with ” H ” the short-hilted broadsword sheet that configuration arranges casts (SPST) switch.

  

Circuit is used individual double knife double cast (DPDT) switch will control polarity of electric machinery connective. Pass switch contact, the power source of electric machinery terminal can invert, electric machinery also can invert direction. The 2nd circuit a little a few more complex, use 4 with ” H ” the short-hilted broadsword sheet that configuration arranges casts (SPST) switch.

Mechanical switch is opposite by switch arrange, must undertake with specific combination ability is operated operating or stop dc machine. For example, switch combines control of A + D to turning, and control of switch combination B + C inverts, if plan institute is shown. Switch combines A + B or C + D can make short circuit of electric machinery terminal, cause electric machinery fast apply the brake. However, it is dangerous that with this kind of means use switch also has his, because operate switch at the same time,A + C or B + D can bring about power source short circuit.

Although two circuit above are small-sized to great majority,dc can work well for electric machinery application, but will the mechanical switch combination that we think the operation is different really invert the direction of electric machinery? Not! We can change the hand of relay of a group of Electromechanical to use switch, use individual to – retrorse pushbutton or switch, use solid state CMOS 4066B even 4 bilateral switch.

But implementation electric machinery (reach its rate) two-way pilot another kind of first-rate method is to transistor H bridge-type electric machinery connection circuit is arranged, following place are shown.

Road of Electromechanical of dc of bridge of basic and two-way H

Circuit of bridge of dc machine H

The H bridge circuit above names so, because,be 4 switch (Electromechanical relay or transistor) basic configuration is similar to a letter ” H ” , electric machinery is located in on central lever. Transistor or MOSFET H bridge may be one of types of commonly used circuit of control of two-way dc electric machinery. It uses NPN and PNP in every branch ” complementary transistor is opposite ” , transistor is didymous switch is together in order to dominate electric machinery.

Control an input? ? A with a direction (turning namely) operation electric machinery, and input B with another direction (invert namely) operation electric machinery. Next, through ” diagonal is right ” medium transistor ” ” or ” close ” , the way that can realize electric machinery is controlled.

For example, it is when transistor TR1 ” ON ” TR2 of canal of Ju Jing body is ” OFF ” when, a dot receives power source voltage repeatedly (+ Vcc) , if transistor TR3 is ” OFF ” TR4 of canal of Ju Jing body is ” ON ” , criterion B dot receives power source voltage repeatedly (+ Vcc) . 0 bend over (ground connection) . Right now electric machinery will rotate along a direction, a of terminal of corresponding electric machinery is positive electrode, b of electric machinery terminal is negative pole.

If switch condition is conversed, TR1 is ” OFF ” , TR2 is ” ON ” , TR3 is ” ON ” , TR4 is ” OFF ” , criterion electric machinery electric current will flow along opposite way, cause electric machinery retrorse direction of rotation.

Next, through will contrary logistic n ” 1 ” or ” 0 ” bring to bear on to input A and B, can control electric machinery direction of rotation as follows.

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