DC low-voltage regulated power supply circuit

Published:2014/3/16 21:11:00 Author:lynne | Keyword: DC low-voltage regulated power supply circuit, NE555 | From:SeekIC

Switching power supply portion VD1-VD4, R1, C1, C2 smoothing circuit composed of the rectifier . NE555 and R2, R3, C4, VD6 other components multivibrator circuit , its frequency is about 20KHz. R4, C3, VD5 composition buck regulator circuit , as NE555 provides 12V power supply. High-power tube VT1 and transformer T constitutes a switching circuit . NE555 VT1 working state by the foot control of ③ , the conduction time is determined by the pulse width , the pulse width can be changed to adjust R3 . Wider pulse width , the output voltage increases ; narrowing the pulse width , the output voltage is reduced. VT2 and R8, R9, C6 composition overcurrent protection circuit . When overloaded or short-circuit fault , VT2 conduction, forced NE555 reset stop vibration , thereby protecting VT1 without damage. C7, R10 to protect the network and prevent the breakdown of VT1 ce knot instantaneous pulse . After two secondary windings are rectified and filtered output of 20V and 12V.In order to make simple , switching power supply designed to not automatically regulated , its function is similar to a transformer , only to realize the light of the antihypertensive effect of isolation , voltage regulation implemented by the back of the regulator circuit . 12V DC voltage by 7805 the +5 V output voltage ; 20V adjustable DC voltage to the voltage regulator circuit . No common ground between the two , in order to add or subtract a combination of a variety of output voltages.DC low voltage power supply circuit shown in Figure:



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