Draw Electronic Schematics with CadSoft EAGLE

Step 5 Add resistors

Resistors, simple components that they are, cause a lot of confusion for Eagle beginners, perhaps because the eagle library contains 100+ different package/schjematic options for generic resistors. Or perhaps it's because a search for short word like "R" isn't practical, and a search for "resistor" turns up a bunch of special purpose specific-manufacturer devices.

The general purpose fixed resistor devices are called either R-US (if you like the US zigzag line type
of schematics symbol) or R-EU (if you prefer the European simple rectangle.] The package options
are numerous, but make sense after you realize that there's a common format: "WWLL/SS" where WW is the body width, LL is the body length, and SS is the hole spacing, all in truncated millimeters. A typical 1/4W resistor measures about 2.5mm in diameter and 7mm long; hole spacing depends on how you bend the leads. So R-US_0207/10 is a 1/4W resistor with 10mm (actually 4*2.54, or 10.16mm, since we want to stay close to a 0.1 inch (2.54mm) grid.) R-US_0207/2V is the same resistor mounted vertically with 2.54mm lead spacing. 1/8W resistors are similarly designated R-US_0204/SS"

I'm going to pick a vertical package for use on our schematics, though of course it doesn't matter for the schematic drawing anyway. Perhaps I'll do the board layout in a "related" instructable later...

Comments

[AlamoRobotics]

Thanks for your instructable. It helped me be able to read the component codes in the libraries!