Part dimensions

[NATY]

would appreciate help on how to measure
physical sizes of various components
such as electrolytic caps, pwr resistors, etc

perhaps a ref guide as been unsucessful
on google search or forums here

thanx in advance

 

[KMoffett]

Because of the vast numbers of different sizes for each type of component, you almost always have to back to the manufacturers' data sheets to get exact dimensions.

Ken

 

[Hero999]

Standard IC and semiconductor pinouts can be found on datasheets.

For common ¼W resistors, I allow for 10mm (0.4") between the centre of the pads on a PCB (the pitch) and a minimum of 2.5mm (0.1") between the centre of two resistor pads next to each other.

Capacitors vary more widely, a typical 25V 10µF capacitor has a diameter of 4mm or 5mm has a pitch of 2.5mm, a typical ceramic disc capacitor (50V 100nF) needs 5mm.

Because components vary widely, always read the data sheet.

 

[Boncuk]

I very often find (cheap) parts manufactured in Taiwan (don't call Taiwanese citizens Chinese! ) or Malaysia, such as switches and pushbuttons.

Eagle has no device for them and I usually create those devices quickly. Use a block of foam and a blank sheet of paper.

Press the part with its pins through the paper into the foam. That's the basis for the footprint.

Measure the outer dimensions (plastic body) by any means (a ruler will do, too).

Here are two examples of a commonly used power switch (250VAC/4A) for video players. Pads 3 and 4 are momentary closing contacts when the button is pushed all the way in.

If they are not needed that part of the switch can be removed easily without impairing the function of the main contacts.

Boncuk