The stabilized power unit

the Described power unit is accurate from available elements. He almost does not demand adjustment, works in a wide interval of a brought alternating voltage, is supplied with protection against an overload on a current.

the Offered power unit allows to receive the target stabilized tension from 1 In almost to value of vypryamitelny tension from a secondary winding of the transformer (see the circuit). On the VT1 transistor the comparison knot is accurate: from a cursor of the variable R3 resistor on base the part of exemplary tension (it is set by a source of exemplary tension of VD5VD6HL1R1), and on the emitter - target tension from R14R15 divider moves. The signal of a mismatch arrives on the amplifier of a current executed on the VT2 transistor who operates the regulating VT4 transistor.

At short circuit on an exit of the power unit or an excessive current of loading increases power failure on the R8 resistor. The VT3 transistor opens and shunts a base chain of the VT2 transistor, limiting to that a loading current. The light-emitting diode of HL2 signals about inclusion of protection against an overload on a current.

in case of short circuit inclusion of a mode of restriction of a current occurs not instantly. The throttle of L1 interferes with fast increase of a current through VT4, and the VD7 diode reduces a tension throw at casual disconnection of loading from the power unit.

For regulation of a current of operation of protection between R7 and R9 resistors is necessary to turn on the variable resistor in a rupture of a chain resistance of 250 Ohm, and its cursor to connect to base of the VT3 transistor. Value of a current can be regulated in limits from 400 мА to 1.9 And.

In the power supply is applicable any transformer with tension on a secondary winding from 9 to 40 V.Odnako at small value of tension resistance of resistors R1, R2, R9, R13-R14 it is necessary to reduce approximately twice and to pick up stabilitrons of VD5, VD6 so that tension on the R1 resistor was approximately equal to a tension half on the C2 condenser.

the Throttle of L1 contains 120 rounds of a wire of PEL of 0.6 mm which have been reeled up on an opravka in diameter of 8 mm. The KT209M transistor (VT1) is replaceable on КТ502 with any alphabetic indexes, КТ208 (Zh-m), КТ209 (Zh-m), КТ3107 (And, B). Instead of the KT815G transistor (VT2) it is possible to apply any KT817 series or other similar structure with admissible tension a collector emitter not less than a supply voltage. The VT4 transistor - КТ803А, КТ808А, КТ809А, the series KT812, КТ819, КТ828, КТ829 or any powerful with an admissible current of a collector not less than 5 And and admissible tension a collector emitter more than a supply voltage. VT2 and VT4 transistors are necessary for placing on heat-conducting paths. VD1-VD4 diodes - any vypryamitelny with an admissible direct current more than 5 And and return tension not less tension on a secondary winding of the transformer. Light-emitting diodes can be applied any type.

Knot of restriction of a current is better for altering

. For this purpose it is necessary to exclude the R7 resistor, and the R8 resistor to put the variable. Its resistance choose such that at the minimum current of restriction power failure on it made about 0.6 Century. The working current of the resistor should be not less maximum current of restriction of I _max therefore it is necessary to determine its capacity of P by a formula: P=I ² _max *R8. For example, for an interval of a current of restriction 0.2... 2 And resistance of the variable resistor should be 3 Ohms, and capacity of-12 Century

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