What part is the most important part in building a project? All of them! Okay, bad joke. Selecting the right parts or components for a design is an area where both new hobbyist and veteran engineers struggle. The wide variety of devices make it almost impossible to know if you are selecting the right one.

Looking at a curated List, using component search engines and browsing DIY shops are how I tend to find parts for my projects.

You might want to bookmark these some of these sites so you can use them next time you’re stuck on how to find parts for your project.

Curated Component Lists

These two lists are “hand-picked.” Even if the parts aren’t exactly what you need, they’ll help you narrow down your search. These are good when you already know what kind of part you need: regulator, diode, I2C interface chip or etc.

Octopart’s Common Parts Library

Octopart is probably the internet’s largest raw database of electronic components. The positive is that nearly every part number exists here. The downside is that not all the data is high quality. Other services mentioned here use their database to drive their searches in unique ways.

But, Octopart is also home to the Common Parts Library (CPL). They’ve partnered with a number of companies and organizations to curate down to a common library. These parts can be a great starting point when you’re looking for parts at a high level.

Adafruit’s Part Finder

Not nearly as extensive as the CPL, Adafruit’s Part Finder is wiki-based list of the components. Most of these are very popular parts used in open source hardware designs. To me, the most useful list is the “Electromechanical” section. Which is actually on the top of the list. With so many different types of connectors available, sometimes it is easier to start with these.

Component Search Engines

When you need to do more of a parametric search, there are a number of Component Search Engines out there. Once you know you need a Linear Drop-Out regulator, these engines let you find one that outputs 3.3 volts and up to 100mA. Plus with all 3 of these options, you’ll get some pricing information as well.

Mouser.com (and other distributors)

Electronic Component Distributors like Digi-Key, element14 (Farnell) and Mouser have large amounts of components on their shelves. Which also means, they have one of the most extensive component search engines available.

Using my LDO example, I might just search for “LDO 3.3V 100mA” and then refine with filters. The benefit of using a distributor site like Mouser is that you can buy. The other two searches listed here only let you find parts, but not buy them directly from the search.

Tip: If you’re looking to buy today, don’t forget to tick the ‘Stocked?’ box. It’ll be applied to filters.

SnapEDA

Even though it is a membership based site, SnapEDA is a free service that includes CAD models. Based on the data from Octopart’s database, SnapEDA’s includes not only components but also footprints and CAD models. They’re going one step further and making it easier to design in your parts while you search for the right ones to use.

Even if you’ve already picked your parts out, check SnapEDA’s database to see if this extra information is useful.

Also, you can limit your searches to the Octopart Common Parts Library.

Parts.io

Another part search engine is Parts.io. One of the minds behind this project is Chris Gammell. This is a parametric-style search engine that gives you full control over what to look for. This is another site that requires you to sign-up but is, for now, free to use.

07/11/2015: Chris contacted me regarding a comment I made about their data. I misspoke about the data sources. I’ve removed the incorrect references.

The picture above is just an example of when you drill down into Crystals. This is probably the most extensive breakdown of the search results you’ll find in any of these search engines.

DIY Electronics Shops

Even though poor Radioshack is circling the drain, the DIY electronics movement is stronger than ever. While Mouser or Digi-Key is a great place to buy components, they are more of a “catalog house.” At least, today they are. The new online DIY shops offer more than just raw components. They sell ready-to-use modules for nearly any major project.

AdaFruit Industries

Chances are, if you’re into electronics, you already know the DIY shop: Adafruit Industries. (Actually if you read the first section, you already saw them mentioned once!) Adafruit has a huge inventory of in-house produced modules. Additionally, their learning system has tutorials and resources to make nearly everything they sell usable out of the box. So whether you need a thermocouple, a humidity sensor, a gyroscope, wearable LEDs or fun electronics stickers, Adafruit sells it all.

Tindie

Often you’ll hear the site Tindie called “Etsy for Electronics.” Tindie’s electronics marketplace is full of sellers who are both people or companies. You might find sensors mounted to breakout boards, breakout boards, or fully constructed products.

If you haven’t looked through everything available, I highly recommend you do. You might be surprised to find someone else had a few extra PCBs for something they’re working on and will happily sell them to you. Look hard enough and you might even find a certain bald engineer selling a DVD of video electronics tutorials on it.