Radio amateur power unit

Sooner or later before the radio fan there is a problem of manufacturing of the universal power unit (BP) which would be useful on «all cases of life». That is had sufficient capacity, reliability and target tension regulated largely, besides protected loading from current "overconsumption" at tests and was not afraid of short circuits.
Is offered, according to the author, rather simple BP most satisfying to these conditions for the repetition, providing the stabilized tension 1, 5-24 In at a target current to FOR. Besides, it can work in a mode of a source of a current with possibility of smooth adjustment of a current of stabilization within 10-100 мА or with the fixed values of a current 0,1 And, 1 And, 3 And. />

we Will consider the circuit of the power unit (see fig.) . Its basis is the traditional circuit of a voltage stabilizer, "heart" - chip КР142ЕН12 which is available now to a wide range of radio fans. As the power transformer quite powerful unified nakalny TN-56 transformer which has four secondary windings with an admissible current 3,4 And and tension of each 6,3 Century is chosen. Depending on demanded target tension the SA2 switch connects two, three or four consistently connected windings. It is necessary for reduction of the capacity disseminated on a regulating element, and, therefore, increases of efficiency of the device and simplification of a temperature mode. Really, in the most adverse mode, at the maximum difference between entrance and target tension (certainly if target tension corresponds to a range specified by the SA2 switch) and the maximum current FOR capacity disseminated on a regulating element will make: Ppacc.max = *Imax (1) Rrass.Max (Uvx.Max-2Uvd-Uvykh.Min) = (12,6-2*0,7-1,5) *3 = 29,1 W, where Uвх.max - the maximum entrance operating tension of this range; Uвых.min - the minimum target tension of this range; Uvd - power failure on the diode of the vypryamitelny bridge. It is easy to check that without division of target tension into ranges the capacity disseminated by a regulating element reaches 70 W.
the Alternating voltage becomes straight diode Bridge VD1-VD4 and smoothes out on the C5 condenser. The safety lock of FU2 protects the transformer at failure of diodes of the rectifier. Transistors VT1, VT2 serve for increase in a target current of BP and simplification of an operating mode of the integrated DA1 stabilizer. The R1 resistor sets a current through DA1 opening VT2:
IDA1 = Ubevt2/R1 = 0,7/51 = 0,014 And, (2)
where Uбэvt2 - opening tension the VT2 transistor emitter base. At a current 14 мА the chip of DA1 can work without a radiator. For increase of stability of target tension regulating tension acts in film from the line of R2-R4 resistors connected to an exit of a chip and moves on an "operating" conclusion of 01 DA1 via untying VD6 diode. Adjustment of target tension is carried out by resistors: R4 - is ROUGH" also R3 - "PRECISELY". The stabilizer of a current is executed on DA1, tokozadayushchy R5-R9 resistors and the untying VD7 diode. The choice of a necessary discrete current of stabilization is carried out by the SA3 switch. Besides, on a limit «10-100 мА» smooth adjustment of a current by the R9 resistor is possible. If necessary it is possible to change a stabilization current, having changed face values of setting resistors using a formula:
R = 1,35/Istab, (3)
where R - resistance of the tokozadayushchy resistor, Ohm; Iстаб - a current of stabilization, A.Moshchnost of tokozadayushchy resistors is determined by a formula:
R = I*I*R, (4)
where I - a current of stabilization of a range; R-resistance of the resistor. Really the capacity of tokozadayushchy resistors for a reason of reliability is meaningly increased. So the R8 resistor of the C5-16B type is chosen as capacity of 10 W. In a mode of stabilization of a current (the SA3 switch in situation pro) on the resistor dissipates capacity of 3,8 W. And even if to put the pyativattny resistor, its loading on capacity will make 72 % from the most admissible. Similar to R7 of the C5-16B type has capacity of 5 W, but also it is possible to apply MLT-2. The MLT-2 type R6 resistor, but it is possible to put MLT-1. R9-wire variable resistor of the PPZ-43 type in capacity of 3 W. MLT-1 type R5. These resistors it is necessary to have so that they were cooled in the best way and did not heat whenever possible other elements of the circuit, and also each other. For descriptive reasons adjustments (an established current) on лимбе the R9 resistor do marks 10, 20, 50, 75 and 100 мА, having used external milliampermetry (tester), having connected it is direct to BP nests.
Additional conveniences at work with BP provides the pV voltmeter as which the M95 type microampermeter with a current of a full deviation 0,15 мА is used.
Resistance of the R11 resistor steals up so that to final value of a scale there corresponded 30 V.Takzhe's tension it is possible to use any other measuring head with a current of a full deviation to 1,5 мА, having picked up the tokoogranichitelny R11 resistor.
as switches SA2, SA3 are used galetny - type 11П3НМП. For increase in an admissible switched current equivalent conclusions of three ship's biscuits запараллелены. The clamp is established depending on number of provisions.
the C5 Condenser modular also consists of five in parallel switched-on condensers of the K50-12 type in capacity 2000 мкФ x 50 Century the VT1 Transistor is established to br outside on a radiator in the area of 400 cm2. It is possible to replace it on КТ803А, КТ808А, VT2 can be replaced on КТ816Г. Steam of transistors VT1, VT2 can replace with one КТ827А, the B, In or D.Diody VD6, VD7 any, is better germanic with smaller direct power failure and return not less than 30 V.Diody VD1 - VD4 of the type KD206A, КД202А, B, In or similar are established on radiators.
At independent manufacturing of the TV1 transformer it is possible to be guided by a technique described in [3]. The dimensional capacity of the transformer should be not less than 100 W, it is better 120Вт. It will be thus possible домотать one more winding tension of 6,3 Century. In this case one more range 24-30 will be added In that will provide at a current of loading 3 And the range of regulation of target tension of 1,5-30 Century power unit Adjustment is carried out by br by a known technique and no features has. Correctly collected BP starts to work at once. At work with BP in the beginning the SA2 switch choose a necessary range of target tension, resistors ROUGHLY" and "PRECISELY" expose demanded target tension, being guided according to indications of the built-in voltmeter. As the SA3 switch choose a limit of restriction of a current and connect loading. It should be noted that at all simplicity of the circuit this power unit combines two devices: voltage stabilizer plus current stabilizer. BP is not afraid of short circuits and even can protect elements of the electronic device connected to it that is very important at carrying out various tests in radio amateur practice. />/>/>/>/>/>/>/>/>/>/>/>

LITERATURE
1. Nefedov A.V., Aksyonov A.I., Elements of circuits of household radio equipment, chip: Directory. - М: A radio communication, 1993.
2. Akimov N. N., Resistors, condensers, transformers, throttles, REA switches: Directory. - Minsk.: Belarus, 1994.
3. Semi-conductor reception and intensifying devices: Directory of the radio fan / R.M.Tereshchuk, K.M.Tereshchuk. - Kiev: Naukova thought, 1988. />/>/>

of Radiokhobbi 05-1999