Choice of capacitor footprint, inductance and resistance

Good morning ,
I finished designing my diagram, I want to assign each component to its location I have capacitors and resistance and inductors and a battery, when I opened the library of locations on kicad I found several, is that what Is there a rule for choosing all of this? This is my very first PCB circuit design project so I don’t know, I’ve seen vedios but it’s different each time
Thank you in advance for your answer

The rule is that you choose the footprints that match the physical components that you use.

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Hi @mamel

The English spelling for “candansator” is condenser. Condenser is an obsolete term that has been replaced by the word “capacitor”.

I altered your thread title to use the correct terminology. :slightly_smiling_face:

yes you are right, I am French, I get help from Google translate to ask the questions, it often makes mistakes and I sometimes don’t notice them. my expression may have errors
Thank you

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Even I have not read the current version of it I suggest to read:

It should let you to know everything you need for your first PCB.

KiCad standard way is to make schematic using symbols and then before going to design PCB assign to these symbols correct footprints of elements you have.
The other way (I use) is to have (in your own library) only symbols permanently connected with footprints. So after making schematic I can directly go to design PCB and I avoid the risk of error when assigning footprints.

Whenever Google tells me ‘diagram’ I always change it to ‘schematic’.

And you choose the physical components to meet your design parameters. So, these are all large through hole/panel mount capacitors

and this is a small surface mount resistor.


The size of the components is often dependent on power dissipation or voltage rating. The larger surface mount components are actually quite easy to solder. Through hole components are much easier to use on a breadboard.

Your choice of components depends on many factors. If you are a hobbyist - producing a one off you might well want to just use components you have in your parts drawer but if you are producing a commercial design you need to consider costs/space and many other factors. Many/most commercial products use small surface mount devices for space & cost concerns but may also use larger components in certain areas of the board eg in a power supply.


That’s not small. Take this:

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Don’t sneeze anywhere around here …

And I thought my monitor screen was getting very dusty!

Wow, I haven’t seen those tuning caps for a long time.

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You want some?

I can send you some :rofl:

Mine are definitely 1970s vintage made in France. No cheap modern plastic knock-offs.

Sorry you’ll have to reduce your junkboxspare parts some other way. :rofl:


Think the last time I used one of those massive air gap capacitors was when I messed about with crystal radios in the 70’s. Happy memories of winding ferrite rods and stringing up antenna on the washing line with my dad.

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And just for completeness, there are footprints for these “toobs” too, well usually the sockets.

My past caught up with me when I was presented with old components I used to own on a recent trip visiting relis. :crazy_face: The left two are defunct, the nipple has broken and the getter is white.

About half the components in that photo from @John_Pateman would qualify as museum specimens.

The air variables in that photo probably go to a few dozen picofarads, max. (Their original catalog descriptions almost certainly called out the values in “micromicrofarads” (uuF).) If he really intended to illustrate an old-fashioned “tuning capacitor”, he would have included a multi-section air variable. As I recall, the ones used in MW table radios had one section nominally 360 pF, to tune the antenna coil, and a second section about 150 pF, which set the local oscillator frequency. Perhaps the most sought-after multi-section variable capacitor was the 4x500pF monster used in Hewlett-Packard’s 200-series audio oscillators (and other instruments) from 1940’s - 1980’s.


I have about 60 of these. The ceramic base measures 8mm X 9mm X 4mm. The overall height varies from 7mm (two moving plates) to 15mm (twelve moving plates) and their max. capacitance from 4 to 30 pF.

Good quality stuff: moving plates and shaft are machined from a single billet, likewise the stationary plates. They are assembled by hand soldering the stationary plates to rivets in the ceramic base after fitting the shaft to the base.
They are all silver plated: one day I should polish them all. :wink:

As I mentioned above, mine are French made in the early 1970s and were spares for use in RF stages of high power (<50 KW) FM transmitters back then.

I don’t know who or why retired feline’s post got marked as “the solution”, but I unmarked it and marked John_Patemans’ post instead.

This solution thing is not for having fun or drawing attention to the most hilarious post. It’s goal is to guide others who are later reading the thread to the “best answer” quickly.

Not me, and it won’t be John or Piotr or you or the Cat. That leaves the OP.

I’ve noticed over the months that irregular posters seem to miss-use this function, often marking their own question as the solution. I suppose because their question was solved.

Perhaps the only solution is for someone with the permissions, to scour the threads to determine the correct solution is appropriately recognized. Maybe all those threads with no marked solution need to be checked to see if a solution was posted and then marked as solved also. Then there’s the problem of unsolved questions and multiple correct solutions.

I’m not volunteering.

“Likes” seem to have been abandoned over recent times also.

EDIT: The “Solution” should go to @retiredfeline for “choose the footprint to match the component”. John’s comment is the wrong way around (sorry John), as the OP already has the parts.
So I’ll edit the “Solution” back to Retiredfeline albeit for a different post. (i know how much he enjoys counting his accolades :rofl:)