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A through-hole soldering kit that builds into a compact breadboard power supply. It accepts a DC barrel jack input and outputs a selectable 5 V or 3.3 V regu...

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A through-hole soldering kit that builds into a compact breadboard power supply. It accepts a DC barrel jack input and outputs a selectable 5 V or 3.3 V regulated supply via 0.1" (2.54 mm) header pins that plug directly into breadboard power rails.

The board features an on/off switch, a 3.3 V / 5 V selector switch, reverse polarity protection, a PTC resettable fuse, and a power LED indicator. Stripped wire can also be connected directly through pads within the barrel jack footprint as an alternative to using a DC adapter.

Key Features

  • Selectable Output – Switch between 5 V and 3.3 V regulated output
  • LM317 Regulator – Up to 1.5 A maximum current
  • Breadboard Mounting – 0.1" header pins on the underside for direct insertion
  • On/Off Switch – Convenient power control
  • Protection – Reverse polarity diode and PTC resettable fuse
  • Soldering Kit – Comes as a bag of parts with silkscreen-guided assembly

Specifications

  • Input – DC barrel jack (2.1 mm centre positive)
  • Output – 5 V or 3.3 V (selectable)
  • Regulator – LM317 (1.5 A max)
  • Dimensions – 32 × 32 mm

Package Contents

  • 1× Bare PCB with silkscreen indicators
  • 1× DC barrel connector (2.1 mm centre positive)
  • 1× LM317 voltage regulator (TO-220)
  • 1N4004 reverse protection diode
  • 1× PTC resettable fuse
  • 1× 100 µF 25 V capacitor
  • 1× 10 µF 25 V capacitor
  • 1× 0.1 µF 50 V capacitor
  • 1× Red power LED
  • 2× SPDT slide switches
  • 4× 0.1" header pins
  • 2× 330 Ω resistors (⅙ W)
  • 1× 390 Ω resistor (⅙ W)
  • 1× 240 Ω resistor (⅙ W)
Note: This is a soldering kit — assembly required. Basic soldering experience and a multimeter (for identifying resistor values) are recommended.

Resources

Jargon buster

Plain-language definitions for the technical terms used above.

1N4004
A common part number for a general-purpose silicon rectifier diode. The part number tells you its current and voltage ratings, so you can check whether it is suitable for power-supply, protection, or rectification circuits.
DC
DC means direct current, where electricity flows in one constant direction, as supplied by batteries, USB ports and many plug-pack power supplies. When a product specifies DC, it runs from a DC supply rather than mains AC, so you need to provide the correct voltage and polarity.
DC barrel jack
A round power connector commonly used for low-voltage DC power supplies, often described by its outer and inner diameters such as 5.5 x 2.1 mm. Matching the barrel size and polarity is important so the plug physically fits and powers the device correctly.
LED
A light-emitting diode (LED) is a small electronic component that emits light when current flows through it in the correct direction. Because it only conducts one way, its polarity matters, and a through-hole LED must be soldered the correct way around to light up.
PCB
A printed circuit board (PCB) is a board, usually rigid, with etched copper tracks that connect electronic components together without loose wiring. Components are mounted on the board and signals route between them through the copper layout.
reverse polarity protection
A circuit feature that helps protect the board if power is connected the wrong way around. It matters because it can reduce the chance of damaging the breakout during wiring mistakes, especially in classroom or prototyping use.
through-hole
A mounting style where the component leads pass through holes in a circuit board and are soldered on the other side. Through-hole parts are often easier to handle and solder by hand, which is useful for classroom and hobby projects.

Breadboard Power Supply v1.0 Schematic

Schematic · 13.0 KB · Click any page to view full size

Download PDF

Supplier page — sparkfun.com

Supplier Description · 895.8 KB · Click any page to view full size

Download PDF

Related Tutorials

Free guides on learn.littlebird.com.au

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