Good evening to all… I am completely new to this tool and domain. Asking such a basic question is really frustrating, but not as frustrating as not getting past this issue.
I am trying to reproduce a board in KiCad that has two tubes on it. Each tube has 9 pins, all of which have traces connected. When I find the proper symbol in the library (ECC83 & EF86), there are 2 and 3 units (respectively)… each of which has less than all 9 pins. How do I put a symbol on the schematic that shows all 9 pins?
It’s common to depict a dual device with separate units for each part. This makes it easier to draw the schematic clearly, as the two units operate (mostly) independently. Tube circuits often depict the cathode heaters in a separate unit for the same reason.
If you don’t like the symbols in the standard library, draw your own symbol.
Yes, this is the way to draw it. And this is not a modern EDA “feature”. Pretty much all the hand-drawn valve amp schematics from 60s-70s (Fender, Ampeg, Marshall, etc) have it all split into respective units.
At schematic you have symbols with pins.
At PCB you have footprints with pads.
I suppose that even writing pins you think pads.
I have never looked into KiCad tubes symbols/footprints.
If you have original schematic that has symbol having 9 pins and you want to have your schematic look the same than (I base on what others have written) you have to draw your own symbol (it is not difficult).
But if only at PCB you want to have 9 pad footprint than you not need symbol with 9 pins. Several symbols can make one footprint. They will have to have the same reference ending with letters A,B,…
Thank you all. You are on the right track, particularly the notes about the schematic not having to match the real board. This is at the heart of the issue.
I have an old board in my hand that I am trying to reproduce into the software. I understand that not all of the pins on the tube may be used. Yet, as I look at the back of the board, there are traces from all 9 pins. So, when I am drawing the schematic, I have traces that can not terminate properly because there is no pin for me to terminate them on. Does that make sense?
Going to modern circuits. Take a look at 74HC14 IC in SO14 package (14 pads). It has 6 inverters. If you place at schematic only one inverter symbol than you have only 2 pins but you want to connect to all 14 pads. You need to place at schematic the other inverter symbols all belonging to this one part/footprint, but each symbol can be located in different place at schematic. It is to make schematic easier to read.
User @invntefx has a website with a lot of tube circuits in KiCad. Look at the schematics there to see how it’s done. Here’s a forum topic with some schematics. Notice the Unit letter after the reference designator, e.g. U3A.
This is where to read about how to use Units of symbols in schematics:
That’s it! It never occurred to me that the schematic would have 2 or 3 representations of the same component. Thank you very much - I am back on track.
You what all the tube pins to be shown in your schematic. You will have to draw your own foot print and schematic part to satisfy all the tube pins. 12AX7-ECC83 Mullard.pdf (38.6 KB)
