Volume pilot essence is the component that makes by resistor presses circuit, its principle is the knowledge that cent of resistor series connection presses, its typical circuit is like graph 1-1.

 

 

Input is formed by R1 of signal source Ui, resistor and resistor R2. Cent presses circuit to output voltage U0 to calculate formula to be

 

 

Can see from formula, because denominator R1+R2 is more than R2, so output voltage is less than voltage. Divide that is to say pressing circuit is a circuit that undertakes attenuation to inputting signal. We can pass change R1 or the bulk of R2 changes the size that inputs voltage U0.

 

The impact that controls resistor R2 size minutes to change to outputting voltage:

 

When input voltage Ui and R1 are changeless, if R2 increases, output voltage will increase; R2 is reduced, output voltage also will decrease.

 

Cent controls the impact that resistor R1 size changes to outputting voltage on:

 

When input voltage Ui and R2 are changeless, if R1 increases, output voltage will be reduced; R1 is reduced, output voltage will increase.

 

 

Graph 1-2 is to contain laden resistor cent to press circuit, the RL in circuit is laden circuit, he can be a resistor also can be a circuit.

 

 

Its job principle and above of the introduction same, just be now when analysing circuit, want to regard next cent as to approach resistance the impedance after R2 and RL paralell connection. Right now, the value of laden resistor is less, load is heavier. Load is heavier, the amount that divides the output voltage that presses circuit to drop is larger.

 

 

Volume potentiometer presses circuit in a cent that resistor is equivalent to in circuit, graph 1-3 presses the equivalent circuit plan between circuit for volume potentiometer and resistor cent, among them RP1 is volume potentiometer.

 

 

Of rotational potentiometer turn when the handle, rotor slides on resistor body again, rotor is decided to two piece block value size also changes subsequently. Potentiometer is equivalent to the series circuit that two resistor make in circuit, rotor is the block body cent of potentiometer two resistor R1 and R2, compositive resistor cent presses circuit, commonly used in volume control circuit come here parts of an apparatus.

 

 

Odd track sound control fader is the foundation of all sorts of sound control fader, graph 1-4 is odd couplet potentiometer those who form odd track volume dominates circuit, it is cent of a resistor presses circuit actually, potentiometer RP1 is equivalent to two cent approaching resistance.

 

 

The potentiometer RP1 in the graph measures control circuit with Yu Yin, call volume potentiometer again so. BL1 is loudhailer, its action is date transforms a telecommunication into sound. The action of power amplifier is an output to RP1 rotor signal undertakes enlarge, promote loudhailer BL1 work again.

 

 

 

 

 

To system of timing of asynchronous electric machinery, what speed of round-the-world electric machinery detects is correct with the key that precision will be timing system stability and control precision. To make the system has good stability and wider timing range, this system is used add coder of Li Shiguang report to detect the speed of asynchronous electric machinery, incident management implement in, compositive the signal of orthogonal encode pulse that orthogonality codes pulse circuit can accept photoelectricity coder to give out, through detecting orthogonality codes pulse signal can measure the rate that gives electric machinery and athletic way. The system chooses timer factitive time base, working mode sets timer to count mode for plan of increase and decrease, source of clock of factitive of orthogonal encode pulse.

 

 

Auxiliary power source is the one part with control essential system, small make up the power source that can provide reliable stability to control a system to ensure, design of auxiliary power source chooses linear power source. Its job principle is labour frequency alternating current after step-down of classics step-down transformer again circuit of wave of classics commutate filter, get volts d.c. gets needs power source voltage via chip of 3 upright stabilized voltage again.

 

 

The hardware of system of control of frequency control of two-phase communication electric machinery is overall block diagram, the main circuit that includes to regard power as module with 3 water chestnut, think the periphery that controls core is basic circuit, small make up introduced dc generatrix to had owed the design process that controls circuit of sampling of protective circuit, voltaic sampling circuit, speed and key-press to show circuit in detail. Software and hardware are the two big component of system of frequency control of asynchronous electric machinery, hardware is the foundation of timing system, software is the core of timing system. The actor bad of systematic control ability basically depends on the dependability of software and versatility, the software of system of frequency control of two-phase communication electric machinery needs to satisfy real time sex, dependability and versatility. To improve software efficiency, systematic software uses assembly language to write.