Published:2011/4/19 4:00:00 Author:May | Keyword: pulse width modulated, switching, stabilized voltage supply
In the diagram it is an actual example of pulse width modulated switching regulated power supply. It is Kaige 4D17U type which is produced by Shanghai the fourth radio factory. It is stabilized voltage supply of 35cm black and white TV set.
Its main technical target is shown in the following:
Output voltage: 12V;
Output current: 1A’
Power consumption <20W;
Efficiency >64%
Internal resistance <0.075Ω;
Ripples <15mV;
Commercial power voltage: 160~240V.
In the diagram, full wave rectification circuit consists of 6VD1, 6VD2; 6C3 is filter capacitor; 6C1, 6C2 is used to slack down surge current; free running multi-vibrator consists of 6VT7, 6VT2, 6VT3 and 6VT4, 6C9. At the same time, 6VT7 is switching tube.
When 12V output voltage reduced because of some reasons, the voltage which is got from sample circuit 6R6, 6R9, and 6R8 by error amplifier tube 6VT5 is also reducing. 6VT5’s collector voltage is rising. 6VT3’s base level is rising too. The output pulse of 6VT7 is broadening. Then the reduced voltage is rising again. On the contrary, when output voltage reduced, we can opposite adjust according to this process above mentioned. It can let the output voltage remain stable. (View)
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Published:2011/4/13 4:21:00 Author:Nicole | Keyword: neon-electroscope
When measuring municipal electric power, the weak current flowsresistance and neon tube, making the neon tube luminescence, and the oscillation circuit composed of CMOS IC starts to oscillate, piezoceramics produces a sound. (View)
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Published:2011/4/13 4:13:00 Author:Nicole | Keyword: voltage stabilizing, few residual voltage
This circuit uses the collector of serial transistor as output terminal, the minimum voltage difference between lowest roll in voltage and steady output voltage can reach 1.2V. Adopting two regulator tubes can ensure the output voltage with high stability. Using 2.5kΩ potentiometer can set output voltage to the given value. 1nF capacitance can suppress high frequency oscillation. (View)
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Published:2011/4/17 8:07:00 Author:Nicole | Keyword: larger current, steady voltage, current limit
In figure, the choice of resistances R1 and R2 should meet the condition of R2≧5*R1. Such as R1=0.2Ω, R2=1Ω. In practice, according to the current, R1 should be between 0.1~2Ω, because of UBE=UD, then UR1=UR2, so I2 is lower than 5 times of I3, total current I1=I2+I3≈I4, neglecting the base current of transistor, then I3 is equal to the adjustment current of integrated circuit IC. For large current transistor, the resistance R3 can be selected between 10~20Ω. For small current transistor, the resistance can be choiced of 100Ω. (View)
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Published:2011/4/19 4:25:00 Author:May | Keyword: full automatic charger
working principleDiagram 4-27 is the principle diagram of this charger. The voltage of LM339's pin 5 V5=6V. When the battery voltage E is less than 12V, V4 is less than 6V. LM339's pin 2 outputs high level. It can let 9013 saturation. 3AD30 is on amplified state. The measured value is 300mA when using heavy current to charge. When E≥12V, V5≥6V. LM339's pin 2 output low level. 9013 and 3AD30 is cut off. It adopts 40mA low current to charge to the battery. The curved line of measured charge current is shown in diagram 4-28.
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Published:2011/4/20 9:06:00 Author:Nicole | Keyword: Hisense, TV Power Supply
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Published:2011/4/20 9:06:00 Author:Nicole | Keyword: Hisense, TV Power Supply
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Published:2011/4/20 9:07:00 Author:Nicole | Keyword: Changhong, TV Power Supply
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Published:2011/4/20 9:06:00 Author:Nicole | Keyword: Konka, TV Power Supply
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Published:2011/4/20 4:39:00 Author:Nicole | Keyword: regulated power supply
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Published:2011/4/20 8:08:00 Author:Nicole | Keyword: typical application, charge
The related components information applied in this circuit: TWL2213 is mainly used in power management of portable instruments or equipments which is powered by lithium ion battery such as PAD, telephone, pager. It is also designed for charging to lithium ion battery. The typical circuit is as below:
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Published:2011/4/20 7:52:00 Author:Nicole | Keyword: pin
TWL2213 is produced by US TI Company, it is a new type power management and lithium ion battery charge control IC, it is designed for portable IT products. (View)
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Published:2011/4/20 4:42:00 Author:Nicole | Keyword: 12V regulated power supply, integrated regulator
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Published:2011/3/30 3:28:00 Author:Nicole | Keyword: converter
The figure is a single-ended forward converter circuit composed of two transistors, diode clamped. VTl and VT2 is on/offsimultaneously by PWM pulse excitation. When they off, the voltage on N1 is polarity reversed, diodes VD3 and VD4 on, the potentialis clamped. Therefore, the voltage which is added to collector is equal to the input voltage Ui during the VTl, VT2 off.
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Published:2011/4/1 3:50:00 Author:Nicole | Keyword: single-ended switching power supply
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Published:2011/4/1 3:51:00 Author:Nicole | Keyword: ring switch
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Published:2011/4/1 3:57:00 Author:Nicole | Keyword: linear integrated regulator
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Published:2011/4/1 3:58:00 Author:Nicole | Keyword: integrated switching regulator
MAX639 series fixed / adjustable output multi-function integrated switching regulator circuit is an efficient, multi-function switching regulator circuit, the output voltage is +5 v, the input voltage is 5.5 ~ 11.5V, output current is 100mA. It is efficient, the electronic switch control terminal of the logic level control and the battery-side low-voltage detectionare havethe advantages of low-power, low dropout, multi-functional, it is widely used in portable instruments, meters and so on. The basic application as shown. The typical application circuit of voltage detection can be see as below.
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Published:2011/4/1 3:32:00 Author:Nicole | Keyword: switching regulator
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Published:2011/4/1 3:31:00 Author:Nicole | Keyword: output voltage circuit
MAX660 can be connected into two kinds of output voltage circuit: Voutl=Vin;Vout2=2Vin-1.4 V. Output resistance of this circuit is slightly larger, as shown.
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