The power unit on К143ЕН3А

My working "laboratory" power unit serves more than 20 years. Repeatedly repairing it after extreme loadings, I came to a conclusion that adjustable that protection is necessary. About 5 years ago I developed the power unit circuit on chip К142ЕНЗА, and since then forgot about its repair. The offered circuit of the power unit (BP) can be as a laboratory source of tension with limits of adjustment of tension 3... 30 In, and the charger with adjustment of a current of a charge of the storage battery (AB).

---

of the Fig. 1. The schematic diagram of BP

Chip К142ЕНЗА is an adjustable voltage stabilizer with system of protection against an overload on a current and allows to receive target tension from 3 to 30 In at a loading current to 1 A.Dopolniv it the amplifier of capacity on the VT1 transistor and the adjustable circuit of that protection, we will receive universal reliable BP.

the VT1 Transistor is "umoshchnitel" of the target transistor of a chip and allows to receive a target current to 15 And at capacity disseminated on it to 100 W. For this purpose it not less than 200 cm ^{2 with good ventilation. It is desirable compulsory having blown in the fan.}

the Circuit of adjustment of a current works with p as follows. At current course via the R2 resistor, power failure on it through a divider of tension of R3-R4 and the emitterny VT2 repeater influences an entrance of the circuit of protection of DA1. The R3 resistor limits the maximum current of operation of protection. Reducing R3, we increase the maximum size of a current at which protection works. The R4 resistor establishes a limit of operation of protection.

If BP is offered to be used

as laboratory, entrance tension is desirable to choose about 40 V.Pri etom on BP exit a range of adjustment of tension makes from 3 to 30 Century. It is necessary to consider that at big currents of loading and small target tension on the VT1 transistor the capacity equal will dissipate:

P _{of R} = (U _вх - U _vy ) I _{of N} (W).

Therefore if there is no need for high target tension, entrance tension it is desirable to lower center to 20... 25 Century

Target tension are supervised by p on the voltmeter. For control of a current it is possible to turn on the ampermeter. It is necessary to equip the R4 resistor with a scale, otgraduirovanny from a minimum of a current of operation of protection (at me - 20 мА) to a maximum. As R4 it is possible to use multiturnaround, or any other resistor with the vernyerny device.

At AB charging an operating procedure such:- cursors of R4 and R5 resistors are established on a minimum; - AB is connected by br according to polarity;
- joins a food;
- is established by a regulator of tension (R5) the maximum value. The current thus is absent;
- a regulator of a current (R4) smoothly increases a current to necessary value; - the regulator of tension is deduced by br to a minimum, until then while the current will not start to decrease;
- is finalized by a regulator of tension a demanded charging current. />/>/>/>

If this BP to supply with the timer which is disconnecting it through time, AB necessary for a charging, the automatic charger will turn out.

Author: К.СЕЛЮГИН, Novorossiysk.

/>

/>!>