One, rectification and filter wave circuit

The task of rectification circuit is to use the one-way conductivity of diode, , negative hand in the voltage of 50Hz electrified wire netting that change to turn only way into pulsatile volts d.c. .

Rectification circuit just is alternating current commutation the pulsatile voltage of only way and electric current, because latter contains larger communication part, still need to join filter wave circuit in the output termination of rectification circuit normally, divide communication heft with filter, get flowing volts d.c. thereby.

You Bo form is knowable:

When 1. switch S is opened, two upright voltage are capacitance the maximum that transformer pays a margin.

2. Switch S closes, it is load of resistor of capacitance filter wave namely, when transformer voltage paying a margin is more than the voltage on capacitance when, capacitance charges, output voltage is elevatory, whenCapacitance discharges when, output falls. Charge so fast, discharge relapses slow ceaselessly, get comparative flowing output voltage in laden admiral. When laden resistance is greater, discharge is slower, ripple tension is less, laden resistor hour, discharge is fast, ripple is big, and output voltage is low.

Have the value of output voltage estimation below 3 kinds of circumstances for this:

Wave of 1) capacitance filter, when laden open a way.

2) does not have capacitance filter wave, when resistor is laden, output voltage average to be: .

Wave of 3) capacitance filter, estimation undertakes with next type normally when resistor is laden, press normallyEstimation.

Work to ensure diode is safe, requirement: Different electron equipment asks the flowing level of voltage of its power source is different, it is this to be able to use different filter wave circuit. Have capacitance filter wave, inductance filter wave and circuit of wave of double entry filter commonly (two or component of wave of two above filter comprises) .

 

2, circuit of linear series connection stabilized voltage

The voltage after rectification filter wave is flabby press, when voltage of electrified wire netting or laden change, this voltage can produce change, and ripple voltage big. So, after rectification filter wave, still need circuit of course stabilized voltage, the stability inside the limits that ability makes output voltage be in certain is changeless.

1, stabilized voltage circuit (power source) main function index

The stable voltage of output is worth Vo, imax of electric current of the biggest output, output ～ of ripple voltage V, voltage-regulation coefficient (voltage regulation), This value is less, stability is better.

Output resistor (internal resistance), , internal resistance Yue Xiaoyue is good.

2, the basic structure of circuit of series connection stabilized voltage is basic train of thought:

 

 

Series connection:

Should input voltage (when VI) is changed, can self-adjusting (the size of VCE) voltage, make output voltage (Vo) keeps constant. For example: The →IB↓→VCE↑→Vo↓ after VI↑→Vo↑→ classics sampling and enlarge circuit

Circuit of series connection stabilized voltage is basic structure:

VI is the voltage after rectification filter wave, t is in charge of to adjust, a magnifies to compare circuit, VREF is fiducial voltage, it is in charge of Dz and R of current limliting resistor to form by stabilized voltage. R1 and R2 form feedback network, it is the sampling segment that uses report to output voltage to change.

Circuit also can change a picture to become the following form, so that see a picture,go to the lavatory.

Be like a circuit of series connection stabilized voltage to regard feedback amplifier (the input is VI, output is Vo) , criterion this kind of circuit belongs to voltage series connection to lose feedback.

In deepness negative feedback condition falls, , .

Of circuit of this kind of stabilized voltage advocate loop by adjust tubal T and laden photograph series connection to form, and T job is online character voice, reason calls circuitry of stabilized voltage of type of linear series connection.

Output voltage Vo=VI-VCE, its change is measured by feedback network sampling, and classics enlarge circuit (the base voltage that control goes to adjusting tubal T after A) magnifies, change the VCE size that adjusts tubal T thereby.

When the input voltage VI increases (or load current Io is reduced) when, bring about output voltage Vo to increase, turn over VF=R2Vo/(R1+R2)=FvVo of voltage of make a present of to also increase subsequently (Fv is feedback coefficient) . VF and photograph of fiducial voltage VREF are compared, after classics of poor value voltage magnifies circuit magnifies quite, its make the VB that adjusts a canal and IC are reduced, VCE of the voltage between the C-e that adjusts tubal T then increases, make Vo drops, maintain Vo thereby basic and constant. Apparent, this is fundamentality of circuit of voltage negative feedback can.