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Using a fixed regulator of variable power supply circuit

2015-03-24 16:43  
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This article is to explain a fixed variable power supply regulator circuit. The circuit is simple but effective. For your more thorough grasp of this principle, we suggest that you can know more about some of the important components of the circuit, for example: 7805,2200 u . Specific inductive ferrite (core) is important. A core should choose to work at a specific frequency by manufacturer. L1 is a powder core and a 32-turn 0.75 mm line. 240 v transformer has a primary and a secondary rated 24 v at 2 a. Contains four diode bridge rectifier, the rated current requires a high output current of the transformer; diode may be damaged if it is not current. I use the MR751 is rated 6 amps, but another good choice is 1 n5400. Mainfiltering capacitor C1 is, power is supplied to further smooth the combination of L1 and C3. C2 and C4 are decoupling capacitors; their actions to further reduce the ripple factor. Regulators, U1 using mobile Zener diode ZD1 in parallel with the potentiometer, R1. Tuning operations generate variable regulator output R1. The output voltage is variable from the regulator output regulator output zener voltage. 7805 10 v regulator regulator and the adjustable output from 5-15 volts. Regulatory authorities may change with different output voltage regulation. The zener should be rated a minimum of 1.3 watts. 



Parts List:
T1 Transformer 10:1 Secondary 24V @ 2A
BR1 Bridge Rectifier 50V PIV 2A rating
C1 4700u (35V)
C2 0.001u
C3 2200u (35V)
C4 0.001u
C5 4.7u (25)
C6 0.01u
R1 10k potentiometer
L1 see text
U1 7805 N.B. This may be changed for different output voltages e.g. 7812 for higher output voltage
ZD1 15V zener @ 1.3W

Formula for calculating Ripple Factor in Filters:

ripple formula

Φ = Ripple Factor
F = frequency of supply in Hz
L = inductance of L1 in uH
C1 = capacitance of C1 in uF
C3 = capacitance of C3 in uF
RL = load resistance in ohms


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