Getting Started: Power and Ground?

Schematic
1

Good morning all,

I’m starting on KiCad and I’m reading the Getting Started and I have some questions.

I have a LED circuit project, of a single layer and an Aluminum PCB with two terminal block (with two polarity each in order to connect several PCBs in series or parallel) then two LED SMD in series, Here is the technical sheet of the components :

https://www.wago.com/global/pcb-terminal-blocks-and-pluggable-connectors/smd-terminal-block-with-push-buttons-in-tape-and-reel-packing/p/2061-602_998-404

https://cree-led.com/products/xlamp-leds-discrete/xlamp-xp-e2

In the schematic part, It is indicated that we need to create a Power and Ground symbol, However, I do not understand how to connect the components to these symbols ?

Here is my schema :

Screenshot from 2022-03-26 09-07-24
Screenshot from 2022-03-26 09-07-241087×388 2.61 KB

Since it is a circuit of a single layer, I guess the Power and the Ground is not required ?

How is the electromagnetic compatibility on this kind of printed circuit ?

Here I ask myself questions about the design of an aluminum printed circuit on a single layer ?

Thanks!

2

Try to connect PIN 2’s net to ground symbol.

To add ground symbol, you can press ‘P’ button, and then choose GND.

3

I hope that you have a way to limit the current through the LEDs and are not connecting the (two in series connection) directly to a low impedance voltage source. Without a way to limit the current, damage to something seems likely.

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4

I’m think he may be using a driver for this circuit that takes care of power?

For such a simple circuit you don’t really need the power symbols. But…

image
image1054×350 5.09 KB

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5

Thanks a lot for your answers! OK it is understood!

Yes indeed the power supply will be a constant current driver.

For Ground Plane, Do I have to make a manipulation on “PCB Layout Editor” or I can only link the tracks ?

Should I still create an appropriate zone?

I will read the rest of the tutorial on PCB Layout Editor now :slight_smile:

6

If you care only about lighting the LEDs, then the method of connecting them will not be so critical. Tracks alone or tracks + plane (where you have room) will work for this simple DC circuit. Normally with a 2 layer board you would have a ground plane covering most of one layer, but you have fewer layers (1) and not much noise sensitivity.

Will the aluminum substrate be connected to anything? I would think it should normally be grounded. That would make a really nice ground plane. I have never designed an aluminum pcb so some of the particulars are outside of my experience.

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7

I think what you really need to understand is the diagram the manufacturer gives for the footprint. I don’t pretend to understand the thermal characteristics needed here. I’m assuming the aluminum is for heat dissipation? You might want to try an electronics site for that kind of information. This site is more related to how to use the software once you know what you want. :wink:

You might also try and buy one of these to see how they are made. This particular design seems pretty ubiquitous. Must be a reason for that.

1 Like
8

Thank you very much for the information!

The aluminum circuit is simply intended to be fixed to an aluminum profile to dissipate heat.

yes it’s exactly the type of circuit that I’m looking to realize Hermit :grinning:

9

If you have two LEDs in serie powered with constant current that it is OK.
But you have second terminal block to connect next two LEDs (in serie) in parallel to this two LEDs.
In such case you can’t assume that current will just divide equally between these LED pairs.

11

Thank you very much Andy_P for the explanation :slightly_smiling_face:

I understand much better, Indeed I start in electronic design and I had some doubts for a basic printed circuit like this one, I’m just trying to follow the Getting Started from where my question on the Power and Ground …

as it is a circuit board of a single layer, on PCB Editor, the minimum number of layer is two, Is there a way to specify a single layer ?

Thanks all!

12

Hello and welcome,

I noticed the "Getting Started"comment.
There are two “getting started” just to be confusing.
The old one in “Help” and the new one in Kicad docs… see below:
https://docs.kicad.org/6.0/en/getting_started_in_kicad/getting_started_in_kicad.html

13

Ordering PCB you should be able to specify that you want one layer board. You can just not generate the not needed gerber files.

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