Reverse engineer a pcb in kicad

Hi everyone,
I am trying to do the schematic from this pcb; I am new using KiCad so at the moment my problem is to insert in my schematic the right type of simbol for the ten elements that I mark in red.
I don’t know what they are called and the size.
Any hel would be appreciate.
Thanks in advance.

But they have the references J1…J5. It looks that they are 5 elements with 2 pads each.
May be it is in some way differential signal so the whole are not separate 8 paths but 4 pairs of paths.
You should first decide if you need one pin symbol or two pins symbol.
I don’t use KiCad libraries so don’t know the most standard symbols for it.

Hello @Antani_Perdue

What is the purpose of the circuit?

it could be one of this connectors (pure speculation!)


you should measure the distance between the holes, normally the reference name J* are associated with some kind of connector or header, so choose one that fits your holes.

OP is asking for symbol not for footprint. If I were familiar with KiCad libraries I would probably knew the general symbol for 1 or 2 pin connector.

I’d wager a dollar that they are LED’s (probably Clear with a Holder (I have a tray full of them)). They are used to mount LED onto Faceplates/other…

The ‘Clue’, as I see it, is the Flat on the only the bottom side… And, can almost clearly see the Anode/Cathode through the clear top. Image below

Screen Shot 2023-05-08 at 13.46.50

UPDATE: Perhaps I loose a Dollar (?)… I threw an LED into a housing to realize it Covers the Flat (not that the LED’s in photo couldin’t be sitting on Top of housing). Photo attached
Also, as others mentioned, “J” is usually for Connectors but, not everyone abides by standard notations…

You lost a dollar.
It’s mounting holes for PCB screw terminals with 10 mm (0.4") spacing. Fits with the rest of the PCB.
Power in (J1), four +/- outputs from 8 TO-220 power transistors.
P1 is the 0.1" input connector for the control signals.

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I anticipated loosing. If I had a Dollar for every Dollar I’ve lost, I’d be wealthy.

According to my maths, you’d be at zero… :slight_smile:


Hi and thanks to everyone for all the reply.

I realize just now that I did not upload the other pic of the pcb; I don’t have the pcb but only this two photos.
I will try to explain better myself.
If you notice they use this kind of blue connector that I suppose have male pin to plug in the J holes and soldered on the other side of the pcb and also have screws to receive conductors.
So my first problem is that I don’t know what this blue connectors are called and their geometry in case I cannot find symbols and footprint in kiCad.
In order to create this kind of footprint I need to know diameters; ok let’s start a few steps back, what kind of footprint I need to receive this kind of blue connectors? what kind of geometry and what are they call? Pad? Via? (I am a bit confuse about all this terminology).
My plan is to obtain a correct gerber pcb file and use one of those pcb online makers.
There are on the top of the pcb 7 elements connectors, the first one has three space footprint and the others two ( I suppose who did the pcb choose this way to create a suitable spacing among the holes).
Finally this pcb is part of a RGB 8x8x8 cube project but usually this kind of project use one big pcb with all the componets on and this would be to hard for me to assemble it so I use instead 25 small pcb to do the same job.
Thank you very much for your help.

Those are called “terminal blocks” or “screw terminals.”
DigiKey has 34,000 types of them:


This picture is from the first page of Aliexpress (a good site for pictures) with the search “terminal blocks through hole”. Generally these blocks will clip together with a spacing of 2/10th inch (5.08mm) between pins. It appears every second screw and associated metal-work has been removed from similar connectors on your PCB.

At the top of the PCB you will need 8 pads each 4/10 inch apart with a total distance of 2.8 inches from 1st to last hole. Use holes in the pads the same diameter as the TO220 holes immediately below.

Fantastic information, thanks again to all of you for your help.

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