Hello, it’s the first time i’m creating a pcb with pcb editing software
My scematic is ready an i’m running the ERC check. Lots of warnings and some errors. There is one error (and warning that is related to it) that i can’t seem to fix.
I want to use a transistor array (2 NPN’s= 6 pins) in my project but Snapeda gives me two sections (seems logical, two sperate NPN’s).
But these sections are identical because they have the same filename and the same pinnumbers (??!!). https://www.snapeda.com/parts/BC847BDW1T1G/ON%20Semiconductor/view-part/?ref=search&t=BC847BDW1T1G&ab_test_case=b
So with the symbole editor i just copy the drawing; with pins 4, 5, 3; and change the pin numbers in the copy to 1, 2, 6. This means it stays one symbol that i can associate this single symbol with a single footprint.
Although i have changed the pin numbers so that every pin has a unique name the ERC keeps crying about it that it has multiple identical pin numbers (yes i’ve altered the pin number fields)??
I have erased it and started all over again with this symbol but with the same error.
I’m sure there are dual transistor symbols in the standard KiCad library, look under Device. Some part numbers may even have a dedicated symbol.
IMO just avoid those third party library sites unless you know what you’re doing and have no choice. They’re often more trouble than they’re worth for simple symbols.
Transistor BC847 BDW is available in the Kicad Library “Transistor Arrays” > “Transistor BJT”.
If you click on the arrow beside the information box, above the symbol, displaying “Unit A”, a drop down menu will show, which also includes “Unit B”. Use the correct pin layout version for your package.
Could you explain me (I’m really curious about this) what is the reason someone using KiCad for the first time instead of using default KiCad libraries starts from searching all the internet for symbols/footprints?
From time to time we have here peoples who spend hours on searching symbol/footprint and then days (with forum help) to fix bugs in what they used.
Time they spend on it is enough to learn how to make their own symbol/footprint what would be from my point of view much more rationale.
Yep.
I’ve started a half year ago with a arduino uno r3.
After those C++ struggles i made a real project on a prototyping board (grid holes and copper islands).
This was also a struggle but now it works.
I want to challege myself and make a semi-pro prototype with as much ad possible surface mounted parts. I’ve looked it up and to avoid problems with symbols and footprint (and making pcb’s i don’t realy need or can use) i desided to skip the small stuff take a leap with Snapmagic and Snapeda.
I’m using a 6 hour video of someone that makes a esp32 IoT experiment board with Kicad 9. https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.youtube.com/watch%3Fv%3DLO9AO0XTX3M&ved=2ahUKEwjj6fmQkJ6OAxX0LPsDHZ53PAUQwqsBegQIFhAG&usg=AOvVaw3DVj9d4iuEY81dknIi3iPP
The 3D look great and not having to solder again is sweet. Not having to order the parts separatly, etc…
BTW my project is a watertank levelmeter with uart ultrasonic sensor, 16x2 i2c lcd (with complete menu and one-button operation), valve/pump output command, different allarms (to a alarm output) with mute button for some alarms according to operation mode, usb powered,etc…
Now my shcematic is almost ready and i’m getting lots of warnings because none of the symboles (after erc check) seem to be associated with the footprints! pfff… i found the problem but its gonna take a few hours to fix this.
For that error i’m gonna try the tip i received and try to use a symbol from the standard library or make one myself.
I’m not there yet but with patience and time. I’m past halfway.
I have never went that way because I started to use KiCad from defining my symbol and footprint libraries and I use only my symbols and all my symbols have footprint already assigned.
But if you go standard KiCad way you have a step of footprint assignment.
In other way imagine how many R symbols there would have to be in library.
It is good decision.
Manually assembling SMD is simpler than THT - you need not to constantly turn the PCB over.
Down to 0603 you should not have any problem.
Down to 0805 is quite easy to hand solder. For 0603, it depends on who you ask. I’m over 50 now and my eyesight is not what it used to be, but I’ve got a decent stereo microscope and that even would have been beneficial when I was still 20 years young.
But those dual transistors are a different story. Such a small pitch on a small part is quite finicky to handle. If you do not have experience here, then I recommend to use only single transistors in SOT-23 package. Those are easy to solder. You can also add some of those 6 pinned footprints as “extra’s” (Maybe a small blinking led circuit). There are also “solder challenge kits” which have led’s and other parts in different sizes, so you can get an idea of how difficult it is to solder.
i look the part up on Snapeda (and cheking it out) with the following mandatory requirements:
-download: symbol, footprint, 3D model, datasheet
-must be in stock
downloading everything for that part, putting it in a seperate folder that i use for my project.
copying the *.mod file to the *.pretty project folder
importing the symbol in my project symbol library
importing the footprint in the project footprint library
give the footprint a 3D model (and adjust position when needed)
place the symbol on the drawing
link the symbol to the footprint (that is where it went wrong without knowing)
duplicating the symbol in the drawing if needed
After placing the symbols i draw the connection/wires/nets.
I have to add some net properties for the signal lines.
Next step; after blanc erc check (no errors and my one or two remaining warnings) and
adding net properties; is creating the pcb layout.
It’s my first time ordering a pcb and directly with complete assembly so i want to be cautious not to throw my money away. For now it’s only a single sheet drawing (i should use more then one to keep a clear overview but i fits). My next schematic/project will be a multiple sheet drawing.
I don’t know what Snapeda is.
I am selecting parts looking at digikey, mouser, farnell and our local TME.
Symbol - I’m doing myself,
Footprint - I’m copying one from KiCad and modifying according to my rules,
3D model - In past KiCad installation at its end informed about FreeCAD so I have got it and larned enough to make my 3D models if needed,
Datasheet - download from Mouser or directly from part manufacturer.
I put everything into my global libraries (I don’t use local libraries).
I don’t run ERC to not stress myself
Till now all my KiCad schematics are single sheet.
It looks great if it works. Snapmagic (and Snapeda) are, what i think, a huge online part store.
And by the looks of it (i’m not finished yet) all the info about the part i’ve used in my design will be in the Bill Of Materials that gets send with al the other files to the pcb manufacturer. This pcb manufacturer will then have the tool(s) to order the parts themselves. So i’m making sure the parts i’ve order are ‘on stock’ (this is mentioned in the KiCad BOM as well).
Check out the link to the video i’ve posted. This guy has made smaller tutorials as well (smaller then 6 hours!).
I’m not ‘overwelming handy’ so if this works out fine it will be a blessing for me (and i’m just past 50 so my eyesight is not what it use to be).
Your tip about the drop down menu was the golden one. Unbelievable i didn’t notice that drop down menu. BTW: the symbol i’ve downloaded had a unit A and a unit B.
Thx again for the reply and the help!
