New symbol - Page 1
Forum section: electronics / general

author: bob91343
author_rank: Super Contributor
timestamp: November 08, 2021, 11:31:33 pm
content: I have tentatively fooled around with various schematic diagram drawing software but find it lacking. For instance, I want to draw a diagram of a high power linear amplifier but can't find a triode tube in the symbol library. Further, I find no easy path to creating one.Any suggestions?

author: jpanhalt
author_rank: Super Contributor
timestamp: November 09, 2021, 12:14:24 am
content: Is this for publication or private use? If the latter, just draw a box or circle with the right number of pins. The only thing where what you draw is important is the package, and that's only important when you are making a PCB.If for something public, then just draw it yourself. I am a longtime Eagle user, and for anything other than passives (e.g,. rcl), common logic, mosfets, etc., I usually use my own library. The sooner you get over that hurdle of doing your own devices, the easier life will be. There are sites with professionally designed devices, but I rarely use them.Some examples of those sites:https://www.ultralibrarian.com/https://www.snapeda.com/

author: james_s
author_rank: Super Contributor
timestamp: November 09, 2021, 12:24:44 am
content: Drawing new symbols is easy, I do it all the time. I've seen some people waste a huge amount of time trying to avoid creating new symbols and footprints but once you figure out how to use the editor it takes only a few minutes. For simple parts it's often faster to draw a custom symbol than it is to find one to download.

author: bob91343
author_rank: Super Contributor
timestamp: November 09, 2021, 12:50:36 am
content: Thanks for the replies but it doesn't seem to get me where I want to go. I don't know how to draw or create symbols. I have tried it in several of the low end free packages and I seem to spin my wheels.Can someone walk me through building a symbol? Say, a triode tube with a plate cap. I seem to remember doing this many years ago without a problem but I forgot which program or what procedure.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: November 09, 2021, 12:51:27 am
content: A quick search turned up a valve library, there may be others:https://kicad.github.io/symbols/ValveJust add it to your personal library. If the tube model you want isn't there just take another symbol with the same electrodes and alias or copy it to your symbol name. You may also have to change the footprint or assign it later.Edit: Actually it turns out that library is already in the standard distribution for 5.1.11, not sure why you didn't find it when you ran the symbol browser in KiCad.

author: bob91343
author_rank: Super Contributor
timestamp: November 09, 2021, 04:33:57 am
content: Okay that's good for an EL34 but I want a directly heated triode, in particular the 3-500Z that is so popular with radio amateurs. I need the filament to show in the view.http://www.tubecollectors.org/eimac/archives/3500z(73).pdfI must be missing something here on how to create the part.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: November 09, 2021, 04:56:49 am
content: Maybe if you search a bit or ask on another KiCad forum somebody might have already made such a symbol and published it. Another way would be to take an existing symbol and modify it, it just consists of graphical elements.Sorry, I gave away all my valves ages ago.

author: Zoli
author_rank: Frequent Contributor
timestamp: November 09, 2021, 05:09:18 am
content: Quote from: bob91343 on November 09, 2021, 04:33:57 amLiteraly, I've just took the ECC81, aded one more pin(K1, vertical) and connected to the other side of the cathode. Writing and posting this took longer than modifying the symbol.

author: james_s
author_rank: Super Contributor
timestamp: November 09, 2021, 05:40:59 am
content: There has got to be a bunch of youtube tutorials on how to draw symbols in KiCad? It isn't a complicated process, not nearly as difficult as laying out a decent PCB. A 10-15 minute tutorial ought to be enough.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: November 09, 2021, 05:50:26 am
content: Just to help you avoid issues, if you modify a symbol, first create a private library you can write in, because usually the system libraries are protected, then copy the selected symbol into it before modifying. The ECC81 is a dual triode so if modifying to a single directly heated triode you will want to delete unit B which is the second triode and unit C which is the heater. And you'll want to change the pin numbers of course.

author: Zoli
author_rank: Frequent Contributor
timestamp: November 09, 2021, 06:51:57 am
content: Quote from: retiredfeline on November 09, 2021, 05:50:26 amIf you want to do schematics only, you don't really care about anything, but the symbol. When it comes to sharing, you'd better save the symbol under diffent name, and share the .pdf or the whole directory. If you intend to do PCB's, then you REALLY NEED TO CLEAN UP YOUR SYMBOL, and make sure that everything(unit B,C, footprint) is OK.

author: Karel
author_rank: Super Contributor
timestamp: November 09, 2021, 07:13:51 am
content: Drawing (complex) symbols or footprints in Kicad V5 isn't easy. It's actually much easier in Eagle (at least in V7).Hopefully in KiCad V6 things will turn for the better.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: November 09, 2021, 07:27:18 am
content: Quote from: Zoli on November 09, 2021, 06:51:57 amEven if you don't want to share, you'll want to save the modified symbol if only to save yourself the work of redrawing the modification, changing the pin numbers, and possibly the pin type, the next time you use it for another schematic. If you have been working with KiCad you'll have a personal library anyway. And they are not PDF files or a directory, a symbol library is a pair of files, a .lib and a .dcm.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 09, 2021, 10:11:19 am
content: @bob91343This may help:https://forum.kicad.info/t/tutorial-how-to-make-a-symbol-kicad-v5-1-x/13336Going a little deeper, I searched on using a symbol without a package in KiCad. That is really simple to do in Eagle as symbols and packages are separate. From a brief review, it seems possible in KiCad, but there were posts about getting warnings about the absence of a package.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: November 09, 2021, 10:22:59 am
content: Quote from: jpanhalt on November 09, 2021, 10:11:19 amIf by package you mean the physical housing of the component, this is totally possible in KiCad. A symbol in a library does not have to have an associated footprint or 3D model. The footprint will need to be associated later when you are making a PCB, as KiCad would need to know the dimensions of the package.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 09, 2021, 10:42:32 am
content: Yes, by package, I was referring mostly to the footprint and secondarily to the 2D outline. In Eagle, package and symbol are separate files that are then associated when making a "device." Quite a while ago, there was a post here in which it was pointed out that KiCad libraries had a different structure that more closely associated symbols and packages in the same file. (https://www.eevblog.com/forum/kicad/eagle-to-kicad/msg3032444/#msg3032444)Hence, my caution. I haven't switched to KiCad (yet), but I do prefer having separate package and symbol libraries.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: November 09, 2021, 11:00:45 am
content: I think the documents you read indicate that compliant fully specified library symbols should have an associated footprint. However this can always be overridden in the project, so yes, symbols and footprints are separate concepts. As you would expect; tons of chips use the various DIP and SOP packages, and an IC may come in various packages.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 09, 2021, 11:04:44 am
content: I am confused by the difficulties that people apparently encounter here.It starts with the original question about a triode (whatever that is).In Eeschema (KiCad's schematic editor), just press "a" for add and then start typing "triode" in the search box.The link that jpanhalt posted about making a symbol in KiCad should suffice in that area. I do recommend to start with a copy of an existing triode and then modifying it to your own insights.Starting with an example shows you already what it looks like, and it keeps the form of the symbol in line with the other library symbols.Creating and managing schematic symbols (ditto for footprints) is quite easy in KiCad. If people perceive it as "more difficult than in eagle" then it very likely is because they have years of experience in that other program and have forgotten about the learning curve in that program, and have to learn it again in KiCad because it works a bit "differently".I switched to Linux some 6 to 8 years ago and for this I needed a Schematic + PCB program that works with Linux. I tried Eagle back then (and about 6 others) but I found it an annoying program to work with. I wanted to add a 0.2 Ohm resistor to a schematic, and Eagle would not let me do that.Then I looked further and found KiCad. The way that KiCad works fits better with the way my brain works. Back then it had quite a bit of rough edges and some things (such as library management) did not work properly, but KiCad has made leaps of progress since then.

author: Karel
author_rank: Super Contributor
timestamp: November 09, 2021, 11:31:41 am
content: Quote from: Doctorandus_P on November 09, 2021, 11:04:44 amIn KiCad V5 there’s no ‘E’ (edit) command in the symbol editor for circles and polygons.The only way to change the size of a circle is to delete it, set the grid to an appropriate size and try again.Creating polygons with curved lines in a footprint is a breeze in Eagle. It's not possible in KiCad V5.One of the more experienced people on the KiCad forums wrote "KiCad’s drawing capabilities are quite limited. It’s not a mechanical CAD program."when I was asking how to create a certain footprint.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 09, 2021, 11:47:11 am
content: Neither is Eagle ver. 7.xx a decent mechanical CAD program. When it is a matter of creating something complex (e.g., a PCB outline), I revert to a conventional mechanical CAD and import it as DXF. That is easily aligned with the origin. Then you are done. I did not intend to draw this conversation into a comparison of the two programs.

author: bob91343
author_rank: Super Contributor
timestamp: November 10, 2021, 06:34:50 pm
content: After reading all the replies to my original post, I am as confused as ever. Apparently there is no simple path to do what I want. I can modify an existing part if it has all the stuff I need, according to some of the replies. Starting from scratch is possible also but I still don't know just what to do.I will do some youtube research to see if someone has described a sensible procedure.

author: james_s
author_rank: Super Contributor
timestamp: November 10, 2021, 08:20:33 pm
content: I'm confused about what is confusing about the process, it's dead simple.Here is a tutorial that shows it from end to end in just over 11 minutes.