Lesson 7 – Building the DIY UNO (Part 1): Power Section & Foundations
Today marks the beginning of your most ambitious project yet: building your very own Arduino-compatible UNO board entirely from components. In Part 1 of this 3-part build, we focus on the power section and foundational components—laying the electrical groundwork that will bring your custom board to life.
All EasyEDA Schematic and PCB wiring guide can be found at:
There are three different wiring guide that you can use for this lesson.
Standard version that has no ICSP and FTDI pins but follows the standard pin layouts of the UNO board.
Full version for DIY hardcore soldering master. ICSP and FTDI pins included
Simple version for beginners in soldering. HIGHLY RECOMMENDED!. Easiest out of the three. No ICSP and FTDI pins and does not follow the standard pin layouts of the Arduino UNO. Prioritizes easier wiring layout.
🧠 What You’ll Learn
The role of the power section in an Arduino-compatible board
You’ll learn how a voltage regulator, protection diode, capacitors, and power indicator LED work together to safely deliver clean 5V power to the microcontroller and components.
How to properly plan and lay out your perf board build
We’ll cover layout strategy tips using EasyEDA layout guide, minimizing wire distance between parts, and ensuring external connectors are accessible.
How to solder core power components step-by-step
You’ll install and solder a DC jack, 7805 voltage regulator, 1N4007 diode, electrolytic and ceramic capacitors, and a power LED + resistor—all while learning best practices for reliable, safe soldering.
How to troubleshoot and verify your power system using a multimeter
You’ll test for 5V output, check diode polarity, and use continuity mode to confirm everything is connected correctly before adding sensitive components.
🔧 Hands-On Practice
In this build session, you’ll:
- Solder the DC power jack at the edge of your board
- Connect the 7805 voltage regulator with correct orientation and spacing
- Add the 1N4007 diode to protect against reverse polarity
- Install electrolytic and ceramic capacitors for voltage smoothing
- Add a power LED and current-limiting resistor to visually confirm operation
You’ll use your multimeter in both continuity and voltage modes to:
- Verify all ground and power rails are connected
- Check that the output pin of the 7805 delivers a stable 5V
- Confirm the LED lights up and the diode is protecting the circuit as expected
💡 Soldering Tips and Tricks
- Heat the component lead and pad before applying solder
- Avoid using too much solder—just enough for a clean, shiny dome
- Use a damp sponge or brass wool to keep your iron tip clean
- Reheat cold or dull joints to ensure reliable connections
🔄 Reflect and Review
- Did your power LED light up when voltage was applied?
- Was your 7805 regulator output reading close to 5V?
- Were there any cold solder joints or mistakes you needed to correct?
📚 Homework Assignment
- Use your multimeter to verify all critical connections in the power section
- Check that your diode is correctly oriented and functioning
- Reflow any solder joints that appear dull, weak, or bridged