Explorer Uno PCB Template




Introduction: Explorer Uno PCB Template

About: Patchr makes PCB design a snap. With our software, you can go from idea to a completed board in days, not weeks. Design your PCB projects with Patchr!

If you’re like us, you spend a lot of time prototyping new projects, starting with a breadboard, a handful of jumper wires, and whatever microcontroller seems to be an ideal fit for our vision. But there is something about the breadboard that feels unfinished.

This really left us thinking: How can we create a quicker path to PCB for all those who design with the open-source hardware we have come to love? So we looked at the projects we’d built and found commonalities in the circuits, which we then used to create a pre-built, verified, ready-to-use template.

We’d like to introduce you to the Explorer Uno. Our first template, based on the board that started it all, the Arduino Uno. With the Explorer Uno, all you need is a breadboard, an Arduino Uno project and Patchr to make your idea a reality. We’ve used this template in everything from cosplay to IoT to #badgelife and art installations — anything that wasn’t possible with a bulky Arduino. We hope you use the Explorer Uno to start down the path to discovering the PCB projects that make you most excited.

Project Level: Beginner to Advanced -- Time Needed: 5 min - Design, 1 hr - Assembly

Step 1: Tools & Materials


  • ATmega328P (Through-hole)
  • 16 MHz Crystal
  • 20 pF Ceramic Disc Capacitor (x2)
  • 5mm LED (x2)
  • 10k Ohm Resistor
  • 220 Ohm Resistor
  • Slide Switch
  • Momentary Button
  • 9V Battery Clip
  • 6 Pin Female Header
  • 8 Pin Female Header (x2)
  • 3 Pin Female Header



  • Soldering Iron
  • Lead Free Solder
  • Wire Cutters

Step 2: Why We Love the Explorer Uno

The Explorer Uno is perfect in that it has all the GPIOs you have come to love with the Arduino Uno with the ability to connect directly to them and delete the pins you don’t use. We’ve put together a diagram for you that shows which components are vital and which ones you can remove.

Step 3: Designing and Exporting

*Phew!* Now it’s time to build this thing!

Check it out — all we need to do is log in to Patchr, select the “Explorer Uno” template next to the create new project button, annnnnnnnnd… Bada bing, bada boom! It’s ready to go. You can change the board footprint, add components, or just export as is.

We've included a BOM with the correct components linked below or you can use the component section above to buy items individually.

Step 4: Assembly!

Once you've received your components and your PCB, you're ready to assemble them. There are a lot of configurations that can work, so keep in mind the final shape of your PCB is entirely up to you and the project you are building!

Step 5: The Brains

Let's start with the core of the Explorer Uno, the ATmega328, the brains. This is what tells your project what to do and when to do it.

Tip: Make sure that the indent on the top of this chip is facing down. You can also use a 28 pin IC socket to make it a bit easier to program and flip in case the ATmega328 is upside down.

Step 6: Button & Resistor

This helps reset your project once the software has been uploaded into the ATmega328.

Step 7: Clock & Capacitors

Time! This 16 MHz beauty counts the seconds so you don’t have to.

Step 8: Switch

On and off, on and off, on and off. We added a red LED so you can tell when the Explorer is on.... or off.

Step 9: LED Pin 13 + Resistor

This is your proof of life light when uploading software or running simple sketches look at this light to be sure everything is running smoothly.

Step 10: Voltage Regulator

This bad boy helps make sure the only thing you are blowing is people’s minds… and not the components on your PCB. We like to use a 9V battery to power our projects, and this will drop it down to 5V to keep everything running smooth.

Step 11: Power

There are so many options here. You can use anything that supplies 5V or more. Just connect the positive and negative leads to the through holes as shown in the diagram above.

Step 12: Headers

These are totally optional — we like to keep them open to solder directly to or you can use jumper cables and female headers to prototype with.

Step 13: Programming the Explorer Uno: Option 1

So here’s the fun part. Let’s upload your sketch to the Explorer Uno. We suggest you do it in one of two ways. The first is to place your ATmega328 in an empty Arduino Uno and upload how you would normally upload to your Arduino.

Step 14: Programming the Explorer Uno: Option 2

The second is to use an empty Arduino Uno as a bridge to the Explorer Uno to program it. You will want to wire up the Arduino using the diagram above.

Upload your sketch from the Arduino IDE as usual, just be sure to select the microcontroller "Arduino Duemilanove or Nano w/ ATmega328" before you upload.

Step 15: Party Time!

We hope this helps you create exactly what you’ve imagined! Please don’t hesitate to reach out with any questions! We are here to help.

Step 16: Bill of Materials

We've added a .csv file that will help you purchase the components for the Explorer Uno. There are Digikey links as well as a link to Adafruit to get pre-bootloaded ATmega328Ps.

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    Question 2 years ago

    beau projet mais
    ou se trouve le schéma de la réalisation ?


    2 years ago

    Looks great, but i dont really understand why it is better for projects than the UNO,it IS a UNO, albeit without the FDTI


    2 years ago

    A few suggestions:

    Use descriptive info on the silkscreen. "header" for instance isn't nearly as useful in the completed project as actual pin signal designations. Same for labeling the power connection, and identifying pin 1 for the µC (the square pad at pin 1 is not going to be very visible once parts are in place - and you're suggesting users possibly remove the µC and put it in an Uno to program it, so there's an increased chance of error here) and the ISP header (a silkscreen outline of the 2x3 IDC connector with the keyway on it would work nicely). The Vreg could use a pin 1 identifier as well (or a thicker line on the side where the tab is) - there is no square pad identifying pin 1.

    Many clone Uno PCBs have soldered-on SMD ICs instead of DIP - users cannot de-socket the µC in that case. Also, repeatedly de-socketing the µC will invariably lead to a damaged pin, rendering it no longer a useful Uno. Instead, might I suggest that you consider flashing the Uno with the "Arduino-as-ISP" program and just make the appropriate connections from the ISP Uno to the ISP header on your project board. Cleaner, and less prone to fault. Better yet, just purchase an "USBASP" dongle, which is like US$2.50 from China, and leave your regular Uno as a regular Uno.

    A nice upgrade might be to use an efficient switchmode regulator instead of a linear, which will be beneficial when running off of batteries (esp if using say a 9V battery).

    I haven't checked the PCB schematics, but even a casual glance at the images you have here indicates that you do NOT have a current limiting resistor for the red power indicator LED - if you're running 5V here, the LED junction is going to fail pretty quick. Probably should add a series resistor (as you have for the yellow LED), and consider a higher value resistance than a regular indicator LED, so that the LED isn't drawing a lot of current. 510 or 680 ohms instead of 220 for instance.

    Note your components list does not include the voltage regulator or the PCB itself.