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This question is ultra verbose, but I'm doing this in an effort to help other newbies (like me at the moment) as they first get into a CAD program like eagle. In the past when I've been new to a field I've always appreciated when people wrote out detailed explanations that are aimed for people that don't know what they're doing yet, so I'm try to pay it forward here.


I want to ask a general question in the context of a specific problem:

The scenario

I'm just starting to learn Eagle CAD and I'm trying to build up a schematic of a circuit board I've built.

I have two capacitors in my board that I'd like to add to my schematic:

capacitors I'd like to add

I know I have the following givens to identify the capacitors in eagle's library:

  • They're polarized electrolytic capacitors
  • They're through hole components
  • They're radial capacitors
  • I know each of their diameters
  • I know each of their values (though that seems to be moot when finding the component in the library)

When I look through the eagle libraries I can narrow down my choices a bit based on what I know about the components:

eagle library

But I'm not sure how to find the right component from here.

The questions

  • I know the names seem formulaic, so is there a particular naming convention of the components that I can use to search?
  • Am I even going the right way about finding these components?
  • And I'm talking about these specific capacitors at the moment, but I have the same question about finding components within the libraries in general. How should I go about identifying the library component for physical components I have on hand?

Thanks!

UPDATE: More detail based on the feedback

I immediately got helpful feedback so thank you Eugene, awjlogan,and Steve (and other people that may reply with helpful info in the future).

To help other newbies in the future I thought I'd add a bit more detail about this specific scenario based on the feedback I got.

Vendor specific naming

In my opinion, one of the most helpful pieces of feedback is knowing that the naming conventions are vendor specific and change from library to library.

I find this helpful because it makes me feel a bit less lost when looking through all of the possibilities. When I first started looking I felt like there were secret languages and meanings that I didn't know (and there are), but knowing that these change from vendor to vendor makes me better about it because there isn't some ultimate secret convention that everyone but me knows that I need to figure out, I just need to get to know how various vendors identify their own parts.

I don't know if that's helpful, but it def made me feel better about it.

Looking to the datasheet for the naming convention

This kind of fits into the vendor specific naming, but I wanted to call it out in a different heading.

I should be able to look to the datasheet or catalog for naming conventions and identification.

In this case the capacitors came in a kit that didn't come with a datasheet and I'm not able to find one online, but knowing that I should look to the datasheet for this kind of information will be helpful when I start looking for other part footprints like the buck converter and stepper motor driver that I'm going to add in a bit.

I'm sure this is another "no duh" fact for experienced people, but as a newbie it wasn't immediately obvious.

Pin spacing

A piece I was missing from my list of identifiers above when looking for the component in the library was the pin spacing for the through hole component (facepalm). It's obvious once I read the feedback, but initially I didn't think of that as a variable to include.

pin spacing 1 pin spacing 2

These exact spacings should be taken as rough when it comes to looking in the library it seems, so we're just looking for close matches.

The anatomy of a specific naming convention

Pulling from awjlogan's answer:

Every EDA package will handle its library differently and also, within the tool, it's likely the libraries are not consistent. In the CPOL library in Eagle, you can see in the 'Description' column things like 'E5-8.5' - this corresponds to a radial capacitor, 5(.08) mm pin spacing, and 8.5 mm outer diameter. So, in this particular library it is: E[pin spacing]-[diameter]', with dimensions in mm. You've searched as far as you can, so you just need to select manually now.

This breakdown is ultra helpful when it comes to looking at the names. I knew that the names had a pattern and meaning, but I wasn't sure how it shook out, so knowing that in this library's case the different sections of the names correspond to the common identifiers for the part (and knowing what those common identifiers are). I'm sure if I step through several libraries looking at the equivalent parts I'd be able to parse out the way they embed meaning into their part names.

The specific component doesn't matter much if you're only doing a schematic

This is also a helpful point to know. In this case I am planning on taking the plans over to my local maker workshop and milling out a circuit board so the footprint does matter, but it's good to know that if all I'm planning on drawing out is a schematic the specific component in the library doesn't matter as much. That takes some pressure off.

The components I picked

Based on what I knew before and what I know now I picked the following parts.

Here's the part I picked for the 470uf capacitor: enter image description here

And here's the part I picked for the 100uf capacitor: enter image description here

I think/hope these are the correct pics (def let me know if I picked incorrectly).

Fingers crossed!

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    \$\begingroup\$ Component names are vendor-specific. So no, there is no standard. If you are working with specific vendor, you can look up their datasheet/catalog for naming convention. \$\endgroup\$ – Eugene Sh. Dec 9 '19 at 15:03
  • \$\begingroup\$ Ah ok. These components are from a kit I bought on amazon: amazon.com/gp/product/B01G2XZC56/…. I see the manufacturer as BlueSky, but I'm having a hard time finding the datasheet for the components with a quick search. \$\endgroup\$ – Chris Schmitz Dec 9 '19 at 15:07
  • \$\begingroup\$ Many of us create our own footprints for every part (or copy/modify each footprint into a private library) verified against each datasheet, with leaded components you have some "flexibility" but you still need to be aware of clearance with surrounding components (but route all the traces you want!). There are standards (IPC) for via hole size for each given lead diameter, usually this is given by MFG in the suggested footprint \$\endgroup\$ – crasic Dec 9 '19 at 18:59
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Every EDA package will handle its library differently and also, within the tool, it's likely the libraries are not consistent. In the CPOL library in Eagle, you can see in the 'Description' column things like 'E5-8.5' - this corresponds to a radial capacitor, 5(.08) mm pin spacing, and 8.5 mm outer diameter. So, in this particular library it is: E[pin spacing]-[diameter]', with dimensions in mm. You've searched as far as you can, so you just need to select manually now.

This is just the way things are with tools as there's not really any one obvious good way of doing things - there are a lot of components out there. You just have to accept it or get annoyed (and only one of those gets things done..).

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    \$\begingroup\$ Ah! Awesome, this answer is super helpful. This is some of the detail that I was looking for. Knowing that there's not an exact way of doing it because things vary between libraries, seeing an example of one of the naming conventions even if it's not the same in every library, and knowing the extra details that I'd need for searching (e.g. I didn't realize I should look for pin spacing) are all ultra helpful facts to know. I'm going to update my question to give a bit more detail off of what I learned from your answer. Thanks!! \$\endgroup\$ – Chris Schmitz Dec 9 '19 at 15:19
  • \$\begingroup\$ @ChrisSchmitz - glad that's helpful. I've always found when changing between tools (Eagle, KiCAD, Altium) it's ramping up on the library management which takes the most time. Good luck, look forward to seeing some projects :) \$\endgroup\$ – awjlogan Dec 9 '19 at 15:21
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IPC has some footprint naming convention in place. Have a look at Mentor Graphics LP Viewer, The supplied libraries implement the IPC schema. Footprint naming convention is a prime example for XKCD 927.

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If all you're doing is creating a schematic, then the exact part type you chose to use is not that critical. On a schematic, the symbol for one type of a 2-leaded ceramic cap looks the same as any other type of 2-leaded ceramic cap.

Where it's important to use the right part symbol is if you're going to use the EDA tool to lay out the printed wiring board (PWB) and create the net list file for routing the PWB. If the wrong part footprint is use, then the desired part may not be able to be mounted to the PWB when assembly time rolls around.

Been there, done that!

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