[Convert 0-30V 3A PSU to 5A or more]

Just one more question...What`s the function of R2 and C2?

[Convert 0-30V 3A PSU to 5A or more]

The project's voltage control's range should be changed to match your transformer since it will allow only about 27V but the control will try to force it higher and its output will become full of ripple and poor regulation.

If it will be stable to about 24 volts,than i am happy. ;D I almost never need voltages higher than this,so it is not important to me.

I am using this partlist:

Parts List for 3A Variable Power Supply

*T1 = 30VAC, 4.3A, 130VA stepdown power transformer
*R1 = 2,2 KOhm 2W 
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 10W
R8, R11 = 27 KOhm 1/4W
R9, R19 = 2,2 KOhm 1/4W
R10 = 270 KOhm 1/4W
R12, R18 = 56 KOhm 1/4W
*R14 = 1,2KOhm 1/4W
*R15 = 100 Ohm 1/4W
R16 = 1 KOhm 1/4W
R17 = 33 Ohm 1/4W
*R22 = 3,9 KOhm 1W
RV1 = 100K trimmer
P1, P2 = 10KOhm  linear potentiometer
*C1 = 10,000uF/50V electrolytic
C2, C3 = 47uF/50V electrolytic
C4 = 100nF polyester
*C5 = 220nF polyester
C6 = 100pF ceramic
C7 = 10uF/50V electrolytic
C8 = 330pF ceramic
C9 = 100pF ceramic
*D1, D2, D3, D4 = 6-10A/50V diode bridge module
D5, D6 = 1N4148
D7, D8 = 5,6V Zener
D9, D10 = 1N4148
D11 = 1N4001 diode 1A
*Q1 = TIP31A, NPN transistor, no heatsink
*Q2 = TIP31A NPN transistor
Q3 = BC557, PNP transistor or BC327
*Q4 = Two paralleled 2N3055 NPN power transistors with 0.1 ohm, 1W emitter resistors each
U1, U2, U3 = OPA445AP, operational amplifier
D12 = LED

"*" is a change from the original design.

Do i need to change something,since my transformer output voltage is to low?Or is this partlist ok for stable 0-24V and about 2-3 amperes?

Thanks for the zener suggestion,i will change it if i can find some around here.  :D

Thank you very much for your answers. 8)

[Convert 0-30V 3A PSU to 5A or more]

Hello.
I am building this project and have some questions.
-i have 26VAC/150VA transformer?Is this ok?I think i will never use the psu at it`s limits...
-can i change TIP31A with BD241C?
-my R7 is 0,47E/9W.Is this ok?
-C1 will be 10,000uF/50V
-op-s will be OPA445
-bridge rectifier is 35A,type that fixes on the heatsink
-should i use 2 or 3 2N3055`s

Is there anything else that i should be aware of?

Thanks in advance,BigPoppa