A food of low-voltage radio equipment from a network

Modern figurative and pocket radio receivers, especially import are, as a rule, calculated on a food from two batteries or accumulators and can eat in stationary conditions from any source with the stabilized tension 3 In and an admissible current to 0,2 And. The same tension is necessary and for a food of video games of type "WELL WAIT A MOMENT" and many other devices. The necessary power unit if to try, it is possible to find in commercial shops, but import production and at unfairly high price, and the domestic industry of such power supplies lets out a little. Besides, they, as a rule, have no stabilization of target tension that leads to listening of a network background.

Fig. 5.1

to Collect a necessary source on forces to everyone who is able to use a soldering iron, and it will not demand a lot of time and big expenses.

Here are given by font two options of creation of such circuit, collected on different elements, and concrete you can choose, having got acquainted with their features and proceeding from the possibilities.

On fig. 5.1 is given by font the simple circuit of the power unit on 3 In (a current in нагрузкеке 200 мА) with automatic electronic protection against an overload (Iз = 250 мА). Level of a pulsation of target tension does not exceed 8 мВ.

For normal operation of the stabilizer tension after the rectifier (on VD1 diodes... VD4) can be from 4,5 to 10 In, but it is better, if it is 5. . 6 In — the smaller capacity of a source is lost on a thermal emission by the VT1 transistor at operation of the stabilizer.

In the circuit as a source of basic tension is used by font a light-emitting diode of HL1 and diodes VD5, VD6. The light-emitting diode is at the same time and the indicator of operation of the power unit.

the VT1 Transistor fastens on a heatdisseminating plate. The T1 transformer it is possible to get any from the unified TN series, but it is better to use the most small-sized TI1-127/220-50 or TH2-127/220-50. Will approach as well many other types of transformers with a secondary winding on 5... 6 V.Kondensatory S1... K50-35 type SZ.

Fig. 5.2

Second circuit (fig. 5.2) uses the integrated DA1 stabilizer, but unlike the transistor stabilizer given on fig. 5.1, for normal work of a chip it is necessary, that entrance tension exceeded target not less than on 3,5 V.Eto reduces stabilizer efficiency at the expense of a thermal emission on a chip — at low target voltage the capacity lost in the power unit, will exceed given to loading.

Necessary target tension is established to font by the tuning R2 resistor. The chip is established on a radiator.

the Integrated stabilizer provides with font smaller level of a pulsation of target tension (1 мВ), and also allows to use capacities of smaller face value.
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