Dual Output Adjustable Linear Power Supply +/-1.2V to +/-12V @ 250mA

  • Rajkumar Sharma
  • 609 Views
  • easy
  • Tested

This project is a solution to power up most devices or projects requiring dual (+/-) adjustable power. The circuit consists of a stepdown transformer, bridge rectifier, DC filter capacitors, LM317 positive and LM337 negative adjustable voltage regulators, 2 x trimmer pot for independent output voltage adjust, and power LEDs.

Parts Explanation

  • Connector CN1 : 230V/115V AC Input
  • Jumper J2 : 230V Selection
  • Jumper J1 & J3 : 115V Selection
  • Transformer T1 : Step Down Transformer 12V-0-12VAC Output, 230V/115V AC Input
  • Bridge Rectifier BR1 : Rectifier Converts DC in to AC Supply
  • Capacitors C3, C5 : DC Filter Capacitors
  • LED D1 : +V PWR LED
  • LED D2 : -V PWR LED
  • Resistor R1, R2 : Current Limiting Resistors For LEDs D1 and D2
  • Regulator U1 : +V Adjustable Regulator
  • Regulator U2 : -V Adjustable Regulator
  • Trimmer Pot PR1 : +V Output Adjust +1.2V to +12V
  • Trimmer Pot PR2 : -V Output Adjust -1.2V to -12V
  • Capacitor C1, C2, C4, C6 : DC Filter Capacitors
  • Connector CN2 : Adjustable DC Output
Note1: This power supply supports 230V AC or 115V AC input, Jumpers are located under PCB for input voltage selection, remove input power cable while changing Jumper selection.
Note 2: This power supply contains hazardous voltage at the input, PCB must be installed in an encloser that prevents accidental contact. Use Plastic screws to mount the PCB
Note 3: Heatsink is a must for regulators U1 and U2 @ full load, the heatsink should be mounted with plastic screws and should not touch the ground plane of the PCB.
Note 4: It is advisable to set the output voltage using PR1 and PR2 before connecting the output to the load.

Input Voltage Selection

  • For 230V AC Input: Close Jumper J2, Jumper J1, and J3 Open
  • For 115V AC Input: Close Jumper J1 and J3, Jumper J2 Open

Other Similar AC to DC Power Supplies

Features

  • Input 230V or 115V AC (Use Jumpers to Select 230V or 115V AC)
  • Output +/-1.2V to 12V DC (Dual Output)
  • Output Ripple Approx. 5mV
  • Maximum Load Current 500mA (250mA + 250mA)
  • 2 X Power LEDs, for +V and -V
  • Screw Terminal for AC Input
  • Screw Terminal for Regulated DC Output
  • PCB Dimensions 91.76 x 43.82 mm

Schematic

Parts List

NOQNTY.REF.DESC.MANUFACTURERSUPPLIERSUPPLIER PART NO
11BR1BRIDGE RECTIFIER W10M MICRO COMMDIGIKEYW10M-BPMS-ND
21CN13 PIN SCREW TERMINAL PITCH 5.08MMPHOENINXDIGIKEY277-1248-ND
31CN23 PIN SCREW TERMINAL PITCH 5.08MMPHOENIXDIGIKEY277-1248-ND
42C1,C610uF/25V SMD SIZE 1206MURATA/YAGEODIGIKEY
52C2,C40.1uF/50V SMD SIZE 0805MURATA/YAGEODIGIKEY
62C3,C51000uF/25V OR 2200/25VPANASONICDIGIKEYP13121-ND
71D1RED LED SMD SIZE 0805LITE ONDIGIKEY160-1427-1-ND
81D2GREEN LED SMD SIZE 0805DIALIGHTDIGIKEY350-2044-1-ND
93J1,J2,J3JUMPER(PCB SOLDER) USE SMD 0-OHM RESISTOR SIZE 1206DIGIKEYPCB JUMPERS
102PR1,PR25K TRIMMER POTBOURNSDIGIKEY3362H-502LF-ND
112R1,R21.5K 5% SMD SIZE 0805MURATA/YAGEODIGIKEY
122R3,R4220E 1% SMD SIZE 0805MURATA/YAGEODIGIKEY
131T1TRANSFORMER 3FD-424TAMURADIGIKEYMT2115-ND
141U1LM317-ADJ TO 220STDIGIKEY497-1575-5-ND
151U2LM337-ADJ TO 220STDIGIKEY497-1585-5-ND
162HEATSINK -TO220 AVIDDIGIKEYHS106-ND
172M3 X 10MM SCREW AND NUT FOR TO220 HEATSINK/REGULATORIO AUDIODIGIKEY1937-IO-M3X10/M3HN-50-ND

Connections



Gerber View

Photos

Video

LM317 Datasheet

lm317

PCB

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