0-30V Stabilized Variable Power Supply with Current Control

2013-04-04 07:02 Author: circuit Source: Internet Visitors: Addcomment()

0-30VDC Stabilized Variable Power Supply with Current Control 0.002-3 A
This is high quality stabilized power supply circuit diagram. You will able to adjust the output voltage from 0 volt up to 30 volt DC. You also able to adjust the current output value from 0.002 A to 3 A.

Technical Specifications

 Input Voltage: ................ 24 VAC
 Input Current: ................ 3 A (max)
 Output Voltage: ............. 0-30 V adjustable
 Output Current: ............. 2 mA-3 A adjustable
 Output Voltage Ripple: .... 0.01 % maximum


To start with, there is a step-down mains transformer with a secondary winding rated at 24 V/3 A, which is connected across the input points of the circuit at pins 1 & 2. (the quality of the supplies output will be directly proportional to the quality of the transformer). The AC voltage of the transformers secondary winding is rectified by the bridge formed by the four diodes D1-D4. The DC voltage taken across the output of the bridge is smoothed by the filter formed by the reservoir capacitor C1 and the resistor R1. The circuit incorporates some unique features which make it quite different from other power supplies of its class. Instead of using a variable feedback arrangement to control the output voltage, our circuit uses a constant gain amplifier to provide the reference voltage necessary for its stable operation. The reference voltage is generated at the output of U1.

The circuit operates as follows: The diode D8 is a 5.6 V zener, which here operates at its zero temperature coefficient current. The voltage in the output of U1 gradually increases till the diode D8 is turned on. When this happens the circuit stabilises and the Zener reference voltage (5.6 V) appears across the resistor R5. The current which flows through the non inverting input of the op-amp is negligible, therefore the same current flows through R5 and R6, and as the two resistors have the same value the voltage across the two of them in series will be exactly twice the voltage across each one. Thus the voltage present at the output of the op-amp (pin 6 of U1) is 11.2 V, twice the zeners reference voltage. The integrated circuit U2 has a constant amplification factor of approximately 3 X, according to the formula A=(R11+R12)/R11, and raises the 11.2 V reference voltage to approximately 33 V. The trimmer RV1 and the resistor R10 are used for the adjustment of the output voltages limits so that it can be reduced to 0 V, despite any value tolerances of the other components in the circuit.

PCB - Connections



 Data:

 

Parts List
 

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R1 = 2,2 KOhm 1W
R2 = 82 Ohm 1/4W
R3 = 220 Ohm 1/4W
R4 = 4,7 KOhm 1/4W
R5, R6, R13, R20, R21 = 10 KOhm 1/4W
R7 = 0,47 Ohm 5W
R8, R11 = 27 KOhm 1/4W
R9, R19 = 2,2 KOhm 1/4W
R10 = 270 KOhm 1/4W
R12, R18 = 56KOhm 1/4W
R14 = 1,5 KOhm 1/4W
R15, R16 = 1 KOhm 1/4W
R17 = 33 Ohm 1/4W
R22 = 3,9 KOhm 1/4W
RV1 = 100K trimmer
P1, P2 = 10KOhm  linear pontesiometer
C1 = 3300 uF/50V electrolytic
C2, C3 = 47uF/50V electrolytic
C4 = 100nF polyester
C5 = 200nF polyester
C6 = 100pF ceramic
C7 = 10uF/50V electrolytic
C8 = 330pF ceramic
C9 = 100pF ceramic
D1, D2, D3, D4 = 1N5402,3,4 diode 2A - RAX GI837U
D5, D6 = 1N4148
D7, D8 = 5,6V Zener
D9, D10 = 1N4148
D11 = 1N4001 diode 1A
Q1 = BC548, NPN transistor or BC547
Q2 = 2N2219 NPN transistor
Q3 = BC557, PNP transistor or BC327
Q4 = 2N3055 NPN power transistor
U1, U2, U3 = TL081, operational amplifier
D12 = LED diode
 

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Tag:power supply,stabilized,Variable,

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0-30V Stabilized Variable Power Supply with Current Control has0Comments

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