Symbol with multiple Units?

Hi Folks,

Go easy on me, I’m new and building my first board. In this board I need a DPDT switch, so I found this one:

It’s from C&K and most suppliers seem to have it. It’s small and should do what I want. So I found a symbol file at SnapEDA which I was able to import:
https://www.snapeda.com/parts/JS202011JCQN/C&K/view-part/?ref=search&t=JS202011JCQN

The footprint looks ok, but the schematic symbol seems to be broken into 2 units (A and B) and when I place it in eeschema, I only get one of them. But I need to switch 2 things, how can I get it to present A and B without placing another component in the circuit ?

Is there not a dropdown in the symbol properties panel for choosing unit A or B?

Ok if you did notice just make a copy of the existing unit A symbol and change that to B, preserving the annotation number if present. That’s how you access the other 5 inverters of a 7404 plus the power unit.

Yes, there is. I expected to see all 6 pins/connections though.

The spec sheet from C&K seems to show all 6 here:
image

I don’t understand why I can only use link half the switch up, perhaps I dont understand what this switch can do ?

I have circuits, 3.3v and 5v and when the switch is activated I want to take both from NC to closed. So strictly a DPST would be fine if I could find a small neat surface mount one.

Each unit shows 3 pins at a time. It also gives you more flexibility in placement of the two unit symbols, at the cost of not clarifying that they are ganged. Typically a dotted graphic line is used to indicate that they are mechanically coupled.

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Only if it is not too confusing with these lines.
Most schematics i read did not really include them unless the units are placed right next to each other because they basically switched the same thing (for example in a 3 phase system all 3 switches are connected but the helper contact to indicate the state is then no longer connected with such a line)

ahh thanks, so I might draw it like this in eeschema:
image

I was concerned that placing 2 of them on the diagram would place 2 of them in PCBNew.

But if its smart enough to know they are the same component tha’ts fine. In my case they will both have the reference SW2 so hopefully it picks it up from that.

PS. I will close off pin 4 too, just drafting it out to check I understand it.

Sometimes it’s necessary because the units are quite different, e.g. one of those old-school potentiometers that have a power switch at the start of the arc.

That makes sense, I can understand how that works with some parts, and could work with this switch.

My next problem is the Electrical rules checker is complaining all the pins are connected :frowning :frowning:
image

Anyway, it seems to come through ok in PCBNew, so I’ll keep working on it.

The ERC dialog looks like the one of the nightly builds. Are you aware that they might not be the best idea for beginners? Is it a good idea to use a nightly build version?


And well either there is something wrong with the nightly version you use or there is a problem with your schematic.

For further help you will need to share your exact version info from about->kicad->copy version info (or similar, nightlies might have a different structure for the graphical interface)

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Actually, to show that the two switches are connected with a dotted line, you should have the dotted line connecting the two moveable parts of the switch. See the DPST symbol on this page (I didn’t want to steal their image, so I linked the full page):
http://wiki.dtonline.org/index.php/Switches

As long as one is SW2A and the other is SW2B then they will both link to the same SW2 on the pcb.

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I completely agree with you Rene, I would have preferred to use a stable release. This is the 3rd time I’ve installed KiCad, currently using:

Application: KiCad

Version: (5.99.0-3128-g2198f8666), release build

Libraries:
	wxWidgets 3.0.5
	libcurl/7.71.0 OpenSSL/1.1.1g (Schannel) zlib/1.2.11 brotli/1.0.7 libidn2/2.3.0 libpsl/0.21.0 (+libidn2/2.3.0) libssh2/1.9.0 nghttp2/1.41.0

Platform: Windows 8 (build 9200), 64-bit edition, 64 bit, Little endian, wxMSW

Build Info:
	Date: Sep  2 2020 09:03:15
	wxWidgets: 3.0.5 (wchar_t,wx containers,compatible with 2.8)
	Boost: 1.73.0
	OCE: 6.9.1
	Curl: 7.71.0
	ngspice: 32
	Compiler: GCC 10.2.0 with C++ ABI 1014

Build settings:
	KICAD_SCRIPTING=ON
	KICAD_SCRIPTING_MODULES=ON
	KICAD_SCRIPTING_PYTHON3=OFF
	KICAD_SCRIPTING_WXPYTHON=ON
	KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
	KICAD_SCRIPTING_ACTION_MENU=ON
	BUILD_GITHUB_PLUGIN=ON
	KICAD_USE_OCE=ON
	KICAD_SPICE=ON

Apart from the warnings, I’m going to assume the schematic is ok for now and try to focus on leaning PCBNew.

I’m building on an established project 90% of the work has already been done, so hopefully its not too to apply my modifications to the PCB layout.

To get acquainted with the multi unit symbols, experiment a bit with a regular dual opamp such as the TL072.

It’s a standard KiCad thing, so you exclude possible problems with symbols from external libraries.

Units A and B are the opamps (look at the pin numbering!) and Unit C are the power pins. Make a simple schematic with them, and export / import into PCBnew, to verify that (and when) the different units are combined into a single footprint.

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