0-24VDC Digital PIC Power Supply

This is 0-24VDC digital PIC power supply circuit. This variable power supply controlled with PIC microcontroller. There is LCD display in this circuit which will show the actual value of power supply output. This power supply use push on switch to adjust the output voltage and current value.

Schematic Diagram:



Component List:
C1 = 2000uF per AMP, 40V (adjust capacity to power supply amps)
C2,C3,C12,C15,C18,C21 = 0.1uF CER
C4 = 0.01uF CER
C5A,C5B,C5C,C5D = 0.01uF CER
C6,C7 = 0.05uF CER
C8 = Not used
C9,C11,C19,C20 = 1uF CER
C10 = 470uF 15V EL RADIAL
C13 = 4.7µF 50V EL RADIAL
C14 = 0.001uF CER
C16,C17 = 22pF CER

D1,D2,D4,D5 = 1N4148
D3 = 1N4004
Br1 = 1<10A BRIDGE RECTIFIER (adjust seize to power supply amps)
DZ1 = 1N4751 30V ZENER
IC1 = LM317KCS TO220
IC2 = LM337LZ TO92
IC3 = LT1491CN special HV opamp, do not substitute
IC4 = PIC16F876A
Q1 = 2N3906
Q2A to Q2D = TIP142TU 1 to 5 transistors (adjust quantity to power supply amps)
Q3A to Q3D = 2N3904 (adjust quantity to power supply amps)
X1 = 20 mHz HC49 DigiKey PN: 300-6042-ND
LED1 = T1 3/4 RED OR GREEN LED
LCD = LCD, 2X16, HD44780 intelligent controller DigiKey PN: 67-1758-ND insulate from case
P1 = 500 Ohms
P2 = 10 kOhms
P3,P4 = 5 kOhms
R1 = 1 kOhms 10W
R2 = 1.5 kOhms
R3,R11,R12,R13,R14,R16,R17,R25,R26,R27 = 10 kOhms
R4 = 56 Ohms
R5A to R5D = 0.22 Ohms (adjust quantity to power supply amps)
R6,R28,R29 = 47k Ohms
R7 = as per schematic (adjust value to power supply amps)
R8 = 240 Ohms
R9 = 270 Ohms
R10 = 390 Ohms
R15 = 39 kOhms
R18 = 39 kOhms
R19 = 8.2 kOhms
R20,R22,R23,R32 = 1 kOhms
R21 = 5.6 kOhms
R24 = 33 Ohms 1/2W
R30,R31 = 4.7 kOhms
SW1 = SPST min toggle
SW2,SW3,SW4,SW5,SW6,SW7,SW8,SW9 = NO_SP push button
T1 = 24 V 1<8A (adjust seize to power supply amps)
T2 = 6.3 V, 150 mA
MISC:
3 Terminals
Transistors Heat Sink, up to: 1A = 30W, 2A = 60W, 4A = 120W, 8A = 240W to dissipate
Line filter, Case PCB, IC sockets…
PCB Layout:
Top side:
                         
Bottom Side:
                        
SPECIFICATIONS
VOLTAGE:

• Ajustable from 0 < 25 Volts at a resolution of 100 mV.

CURRENT: choice of 4 ranges;

• 0 < 1.000A at a resolution of 1 mA. JP1 and JP2 open, C1 = 2000uF filter cap., R7 = 0.5 Ohm, T1 = 24V, 1Amp.
• 0 < 2.000A at a resolution of 2 mA. JP1 ground and JP2 open, C1 = 4000uF filter cap., R7 = 0.25 Ohm, T1 = 24V, 2Amp.
• 0 < 4.000A at a resolution of 4 mA. JP1 open and JP2 ground, C1 = 8000uF filter cap., R7 = 0.125 Ohm, T1 = 24V, 4Amp.
• 0 < 8.000A at a resolution of 8 mA. JP1 and JP2 ground, C1 = 16000uF filter cap., R7 = 0.0625 Ohm, T1 = 24V, 8Amp.

2 lines LCD display:

• The top line shows the settings, the maximum current stays displayed at all times, it is not necessary to short the output terminals to set the maximum current.
• The bottom line shows the measured values.
• The arrows at the bottom center line show who is in control, the voltage or the current.

Adjustments:

• Voltage, steps of 1 V and 0.1 V.
• Current, steps of 1, 2, 4, 8 mA and 50, 100, 200, 400 mA depending on the Amp range.
• Memorisation of the last settings before power off, restarting with thoses same settings.