The pulse power supply

 

   The basic electric circuit of the pulse power supply is resulted on fig. 1.  The power supply represents the single-cycle pulse converter of a pressure(voltage) working on frequency, approximately, 50 кГц. Target capacity of a source - 40 watt

   At the moment of inclusion of a feed(meal) condensers S3-S5 are charged through resistor R2. Thus the short-term pulse of a pressure(voltage) from this resistor through diode VD5 and resistor R4 acts on condenser S6 and charges it(him). Stabilitron VD6 limits a level of a pressure(voltage) for a feed(meal) of a microcircuit in size 5,6 V.Eto provides initial start of the circuit and a feed(meal) of the oscillator. Further the necessary having pressure(voltage) for the circuit is removed from a secondary winding (2) transformers T2.

   On elements of microcircuit D1.1-D1.4 the specifying generator of pulses which through resistor R8 act on  condenser C9 is  collected. In result on condenser S9 the pressure(voltage) of the sawtooth form is formed. Comparator D2 compares a pressure(voltage) of a saw to a level of a pressure(voltage) on an input(entrance) 2. On an output(exit) of the comparator pulses which duration is defined(determined) by size of a pressure(voltage) on an input(entrance) 2 are formed. These pulses through the amplifier of the capacity, collected on transistors VT3 and VT4, act on a primary winding of the transformer. The pressure(voltage) from which secondary windings is straightened by diodes VD1, VD2 and acts on outputs(exits) of a source.
From a winding of a feedback 2 transformers the straightened pressure(voltage) through resistors R7 and R9 acts on an input(entrance) 2 comparators, than stabilization of a target pressure(voltage) is provided at change network on an input(entrance) and capacity of loading. The factor of stabilization of the converter depends on an inclination of a saw on condenser S9.

   The diagrams of a pressure(voltage) shown on fig. 2., explain work of the circuit. Transistor VT1 provides protection of the power supply against an overload on a current. At his(its) opening blocking of work of the comparator (works at a broad gully. "0" on input(entrance) D2/6)   the Signal of blocking periodically moves also from an output(exit) of the generator. It excludes a presence(finding) of the comparator in an open condition long time.

   In case of operation of protection to return the circuit in a working condition (to start), it is required to disconnect for some time the power supply from a network (condensers SZ-S5 will be unloaded through resistor R1).

   In the circuit details are applied: resistors R1 — МЛТ, R2 — С5-5 on 1 Вт, tuning  R7 — such as СП5-16ВА-0,25 Вт, other resistors can be любо го type; condensers S1, С2 and С10 — such as К42У-2, СЗ... С5 — К50-29 on 450 In, С6, С7 such as К50-35, С8, С9, С11... С13-К10-17, С14, С15-К10-17. It is possible to replace transistor VT2 on КТ839А.

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Fig. 1. The pulse power supply. The circuit

 

   The throttle of filter T1 is carried out on two connected together ferrite торроидальных cores M2000NM1 of standard size К20х10х7,5 mm. Both windings contain of 0,33 mm (before on моткой it is necessary to round off sharp edges(territories) of the core надфилем) on 40 coils of wire ПЭЛ-2 in diameter.

 

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Fig. 2. The pulse power supply. The form of a pressure(voltage) in control points of the circuit

   For manufacturing transformer T2 are taken ferrite (М2000НМ1) cups of standard size БЗ0. In the central part магнитопровод should have a backlash about 0,2-0,6 mm (that the transformer at work was not sated). Windings contain: 1-120 coils; 2-7 coils of wire ПЭЛ-2 in diameter of 0,15 mm; 3 — 8 coils of a wire in diameter 3х0,33 mm (it is reeled up by three about waters simultaneously), 4 — 19 coils of 0,5 mm.

   Transistor VT2 is established on a radiator, and all design is closed by the mesh screen (for a heat-conducting path from Т2 and VT2). The screen allows to lower a level of radiations and handicapes at work of a source.

   Before inclusion of transformer T2 it is necessary to be convinced of serviceability of the circuit of formation of pulses on output(exit) D2/1. For this purpose a feed(meal) 9 In on condenser S7 from an external source is possible to submit temporarily.

   At correct phasing connection of windings at transformer T2 adjustment(option) of the circuit consists in installation by resistor R7 of necessary size of a pressure(voltage) in a secondary winding and checks of start of the circuit at the minimal having pressure(voltage) of 180 Century.

 

The primary source library.espec.ws.  Ред. 02.06. V.F.Gajnutdinov.


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