0 to 25-volts power supply

my project is to make a 0 to 25-volts adjustable one-ampere power supply,i bought its kit but don't understand its circuit or simulate the output voltage. can anyone explain its schematic diagram.

here's the materials:
ZERO TO 25 VOLT ONE-AMPERE IC REGULATED POWER SUPPLY
Semiconductor
IC1 – LM723CN Voltage Regulator
Q1 – 2N3053 NPN 5-watt 40-Volt transistor (TO-5)
Q2 – 2N3055 NPN 115 watt 60 Volt transistor
D1, D2, D4, D5, D6, D7, D8- MP5081 rectifier diode
D3 – 1N5401 rectifier diode

Resistors ( All are ¼ watt ± 5% tolerance carbon composition type unless otherwise specified.)
R1, R2, R4 - 3.3 Kilo ohms
R3 - 1 Kilo ohms trimmer
R5 – 4.7 Kilo ohms trimmer
R6 – 2.5 Kilo ohms linear taper potentiometer
R7 – 100 Ohms
R8 – 220 Ohms trimmer
R9 – 270 Ohms
R10 – 1 Ohm 1 watt ± 10% tolerance
R11 – 1 Kilo ohm 1 watt ± 10% tolerance

Capacitors
C1 – 0.001 µF/100 Volts polyester capacitor
C2, C5, C7 – 0.1 µF/100 Volts polyester capacitor
C3 – 100 µF/50 Volts electrolytic
C4 – 2200 µF/50 Volts electrolytic
C6 – 1000 µF/25 Volts electrolytic

Others
T1 – Step down transformer 220/110 Volts primary; 28 volts at 1.5 amperes and 12 Volts at 0.5 ampere secondary – ACT-28150M12
Analog Voltmeter 0.30 Volt range
Analog Ammeter – 0-1 Ampere range or better
Terminal posts (1 red and 1 black)
Potentiometer knob
Toggle switch (SPST) as ON/OFF switch
Neon lamp – 220 Volts
AC line cord with plug
1 – ampere fuse
Fuse holder
14- pin IC socket
PCB
Mica insulator (TO-220)
Transistor spacer (2 sets)
1/8” x ¼” bolts and nuts – 2 pcs.
1/8” x ½ “ bolts and nuts – approximately 10 pcs.
No. 20 AWG insulated hook up wire – 2 meters
Rubber grommet, enclosure, solder, etc.

 

Google "lm723" and get the data sheet - it will explain itself.