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Build Your Own 0-15V Dual Polarity Power Supply
Description
This dual-polarity power supply is straightforward to construct, necessitates a limited number of components, and offers adjustable voltage ranging from 0 to 15 volts. It's well-suited for powering op-amp circuits, along with other circuits needing a dual supply voltage source.
Circuit Diagram
Components
- C1, C2 2200µF 35V Electrolytic Capacitor
- C3, C4, C5, C7 1µF 35V Electrolytic Capacitor
- C6, C8 100µF 35V Electrolytic Capacitor
- R1, R4 5k Potentiometer
- R2, R3 240 Ohm 1/4 W Resistor
- BR1 2A 30V Bridge Rectifier
- U1 LM317 Adjustable Positive Regulator
- U2 LM337 Adjustable Negative Regulator
- T1 30V Center-Tapped 2 Amp Transformer
- S1 SPST 2 Amp Switch
- MISC Heatsinks for U1 and U2, Line Cord, Case, Knobs for Pots, Wire
Notes
- Due to the operation from 120 (or 220, or 240, etc.) volts AC, this project must be housed within a protective enclosure.
- U1 and U2 generate considerable heat and will require heatsinks. A fan is typically unnecessary.
- Adding a volt and amp meter is, of course, an option.
- U1 and U2 have a minimum output voltage of +-1.2V. If a lower voltage is needed, two 1N4003 diodes in series with the regulator's output can be added. These diodes each drop approximately 0.6V, permitting a supply voltage of 0V. Note that this action also reduces the maximum output voltage by 1.2V. (Courtesy of Steve Horvath, horvaths@techcomnet.com for the suggestion).
LM317 Adjustable Positive Regulator
The LM317 is a versatile three-terminal adjustable positive voltage regulator. This IC is widely used for creating precise voltage references. Its primary function is to maintain a stable output voltage regardless of changes in the input voltage or load current. The LM317's adjustable nature allows users to precisely set the output voltage within a specified range. It operates from a minimum of 1.2V to a maximum of 35V, making it suitable for diverse applications. The pinout is standard, with pins 1 and 2 defining the adjustable output voltage.
LM337 Adjustable Negative Regulator
The LM337 is a three-terminal adjustable negative voltage regulator. This IC is designed to produce a stable negative voltage from a positive supply. Similar to the LM317, it maintains a consistent output voltage even with variations in input voltage or load current. The LM337 is often used in battery charging circuits and other applications requiring a regulated negative supply. Like the LM317, it operates within a specific voltage range (typically 1.2V to -35V).