This is my first post, so I’m beginning the learning curve. I’m needing to complete my schematic by entering a relay, but cannot seem to locate any within the library (relay_DPDT) that I can identify as a multi-unit symbol. Specifically, I need to put the coil in the front portion of my schematic, but locate the contacts in another location near the end of the schematic. Can someone please help me to:
identify, locate & select a simple med. power DPDT relay that I can split?
2)guide me to any tutorials that may help me in the future, when using relay’s within my schematics? Any help will be greatly appreciate.
Regards
Frank
I’m not using KiCad library so don’t know if there are multi-unit relays.
Sooner or later you will have to learn to design your own symbols - just do it sooner.
There should be enough information in FAQs and KiCad documentations how to start with your own libraries.
A bad idea IMO. You lose the connection between contacts and coil, which will confuse readers (and yourself in a couple of years).
Why not just use local labels and place the relay at the end with two labels to connect the coil to the front of the schematic?
I’m not a great fan of labels, but this is an instance where they’re warranted.
You are dealing with a schematic, so the only difference between low, medium and high power relays is the Value (name of the relay). The symbol (Reference and drawing) is the same for all DPDT relays.
The Footprint and the Pin layout are almost certainly quite different, but the symbol is the same.
Paul mentions above that at least one split version of a DPDT relay exists, so that is half your problem solved. You don’t need to split a relay.
As for the correct pin layout, footprint and Value, you must find the relay you want and use its Data sheet or physically measure all the vital details ( overall size, pin positions, pin layouts etc).
When you have all these details, you Edit the split version of the relay so the pin numbers, Value and footprint match your relay.
Alternatively,
You may find a relay in the library that matches the pin layout, in which case you just have to split the relay and change its Value and Footprint.
Another alternative is you may be really, really lucky and find a split relay with the correct pin layout, so all you have to do is change the Value and maybe footprint.
When you have decided your course of action, please ask if you need help with any of the required work.
Some information is covered in the FAQs accessed at the top of every page of this Forum. There is also massive amounts of information in https://docs.kicad.org/, in particular for newcomers, “The Beginners Guide”.
While splitting the coil and contacts of a relay is probably not wrong, I feel like you are disassociating a logical connection.
When you split a quad NAND gate into four units (and maybe a fifth for power) the logical inputs and outputs of a functional group stay together. Similar for a dual or quad op amp.
I am using the word “logical” loosely. Clearly the inputs and outputs to an op amp are usually analog.
In a relay the coil is the logical input and the contacts are the logical output. Splitting them reminds me of an earlier comment on this forum. Like breaking up your schematic and using a lot of netlist labels to connect the pieces, you end up with a “graphical netlist” instead of a schematic diagram.
I can see that a DPDT relay may make for messy wiring in the schematic. I think that it might make more sense to just use one or two netlist label interconnects if that makes the schematic much more user-friendly.
As a sidenote… Yesterday I was looking at the DMM7002. It’s a benchtop DMM published in the ELV Journal 1989-04 and -05. (This magazine is freely downloadable from the official website). This multimeter has very nicely drawn schematics, divided over 8 different pages. It also has around 25 relays. Below I made a composite screenshot of a part of the input section, and of the relays drivers.
Without splitting the switches from the relay coils, this schematic would have been a real mess. Splitting relay contacts from their coils is pretty much industry standard. It is very often the cleanest way to draw the schematic,
Just for emphasis, below another example of “relay logic”.
