The power supply provides a bipolar output voltage which can be varied from 5 to 25 V.
The maximum load current can be up to 1 A. Exceeding this current or short circuit on the output device is triggered protection and output voltage sharply decreases on both channels. The transformers T1 and T2 are included as a step-down, each of them works on both channels. Rectifiers are implemented with diodes VD1-VD4, the rectified voltage is smoothed by the capacitors C1 and C2 are relatively large capacity. Transistors VT1, VT2 is assembled by the compensation scheme, the voltage regulator channel positive polarity, and the transistor VT9 and the Zener diode VD5 - source reference voltage for the regulator.
The output voltage is regulated by the resistor R5. Transistor VT7 and the resistor R3 constitute the node current protection. When the load current exceeds a given value, the transistor opens and the voltage regulator goes into constant current mode.
Channel negative polarity voltage stabilizer assembled transistors VT4-VT6, and the node current protection - transistor VT8 and the resistor R4. Reference voltage for this regulator is the output voltage of the channel of positive polarity, which, through the resistor R7 is supplied to the base VT4. So when you change a variable resistor R5 voltage of positive polarity will change and the output voltage of negative polarity. This change was synchronous and both voltages were equal, resistors R7 and R8 are selected with equal resistances, and in the circuit of the Zener diode entered antiparallel diode VD7 VD6 and. When normally operating the power supply voltage taken from the common junction point of the resistors with respect to a common wire, equal to zero and the transistor VT3? at the base of which receives this voltage, closed.
In addition to these standardized transformers, power supply you can also use ready-made transformers TC-31-1, or one transformer with a capacity of not less than 60 watts with two secondary windings voltage on 27...30 V At a load current up to 1 A.
- Transistor VT1 can be CTA-CTG, CTA-CTG, CTB
- The transistor VT2 can be CTA,CTG, CTA,CTB, CTA
- The transistor VT3, VT7, VT10 can be CTA-CTV, CTV,CTV, CTV - CTE
- The transistor VT4, VT8, can be CTA-CTC, CTU - CTE
- The transistor VT5 - CTA-CTG, CTA - CTG
- Transistor VT6 - CTA-CTG
- Transistor VT9 - CPD, CPE, CPA, CPB, CPA, CPB
- Diodes VD1 - VD4 - D, DB, D, CDA - CDC or similar powerful
- Diode VD6, VD7 - KD105B, CDG, CDA,CDB, and other silicon rectifier diodes.
- The Zener diode VD5 - XA, XA, KS147A
Powerful diodes can be used without heat sinks, but the transistors and VT2 VT6 must be installed on radiators with total area of at least 200 cm2. When checking the unit if necessary to change the adjustment range of the output voltage should be selected resistor R6. Value current protection operation can be set by selection of the resistors R3 and R4.
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