For my first project in KiCad, I’m making a simple control panel that I can use in my workshop to turn on and off power to 4 devices. (These are connected to an ESP32, so it’s more than just turning them on and off with a switch.) I have switches that are DPST and some optocouplers. I’d like to indicate the switches are DPST and to include that on the schematic as well as the optocouplers. The problem is the devices on the output side of the optocouplers and on the 2nd pole of the switches are off the board and I don’t want to include them in the schematic. I’d rather just have some kind of flag or arrow and label it something like, “To laser control,” or, “To etching laser.” True, both are loads, but their power source is external to my circuit and so is the load for that power.
How would I indicate that in a KiCad schematic so they don’t get flagged as errors? (I get that for a foot print, I can use something like molex pins for connectors, so I see how that works, but I’m not sure about what to do about the actual devices.)
You can’t just have a “flag” for off-board things, you need to represent what you will have on that PCB… so a connector… (which you can put useful words next to). If you just want some PCB holes you can solder wires to, then use something like “Connector pin socket” or “Connector pin header”… so a row of holes that you COULD fit Molex pins to… or just wires.
If you are just using the schematic to document something, then it doesn’t really matter what you do!!
You’d have to connect your external devices in some way to the PCB, and the most logical is to add a connector on the schematic and on the PCB.
For the rest, I do not understand. You have some devices (your switches or optocouplers?) that are not on the PCB, and you don’t want them on the schematic either, so where do you want to put them?
Maybe you could give us a visual help, a photo, a 3D model, or pencil drawing as an example. I don’t understand either what you are doing.
Are the optocouplers etc. completely in this board? If yes, how are they connected to the external something (“off the board”)? Or is the output side of the optocoupler component in the other board, for example so that the component crosses the edges of two boards, one side being attached to one board and the other side to the other board?
Well if they are not part of the board, then the components can’t be represented on the schematic as symbols. Maybe you could import a graphics object to the schematic that depicts the external components. That object could be generated from a separate schematic that isn’t used to make a board, i.e. a separate project.
I did an example of using an optocoupler to turn on power to my CNC or to use a connection on a molex pin to be able to turn on the laser mounted on the CNC.
In both cases, the machine has a DC power supply and I’m using an optocoupler or something else to switch it on and off. I don’t want to have to define a separate power source or load - I wish I could just add something on the leads from the optocoupler or on the molex pins to say something like, “External CNC power,” and “External CNC,” or some way to just specify enough information so when I run a check, it validates it without errors.
I know I can find a footprint for molex pins when doing PCB layout and for whatever connector I use for the CNC wires, but how do I represent the CNC (and laser) with their external power supplies in a schematic instead of just using the input side of the optocoupler in the schematic or just running the wires to the molex pins and not providing any info about what plugs into the molex pins?
As for my question on a switch, I’ll put that in a separate reply, since I am not yet allowed to have more than one attachment per post. (So frustrating - as a newbie, I have more questions and want to be able to clarify them, so, of course, as a newbie, I can’t add more than one image per post to clarify things!)
I don’t need info about the vent fan on the schematic, since it’s a different circuit. But I think I need to represent that it’s a DP switch for clarification. (Also, since I know the editors can produce a parts list for shopping, I want to get used to including all this information.) So if I specify a SPDT switch, and find the right footprint, I have one pole on the switch unused in the schematic. Is that what I should do?
Or maybe I should do something like make up a dummy circuit with a +5 power on one connector on the 2nd pole, then the other connector goes to a load, then to ground? But what info do I provide about the load and how do I provide it? Maybe just stick an LED and resistor in there to represent the full load of the vent fan, since actual vent fan data is not important to the part of the circuit I’m working on - the part that uses the first pole in the DPST switch?
