[DanGT4]

Hello all,

I've purchased a 0.4.4B PCB off eBay in the hopes of making a more durable ECU to replace my 0.4.3 unit that's going in a MX5 powered kit car, but I'm struggling a bit with the symbology convention that's used for the polarity/orientation of the components. Apologies is this is really obvious, but please bear with me as I'm a mechanical engineer and haven't had much exposure to PCB conventions!

I've attached two photos. One shows the capacitor and diode symbol, and the other an IC. I think that the closed end of the capacitor symbol is the anode end, and on the IC the long line offset to one side indicates pin 1 end, but don't know for certain and I'm struggling to find anything on Google.

Thanks for your help,

Dan

[DanGT4]

Any body?

[dazq]

Capacitors don't have an anode end they are + or - , though most on speedy are not polarised.
I would cross reference to the schematic to confirm any components that I am unsure of tbh.

[PSIG]

To be sure, refer to the schematic, and test connections. For example, the U1 pad that connects to R5 is pin 1. Easy would be a multi-meter continuity setting with beep. Or, the D14 diode pad that has continuity to the regulator pin 1 is the cathode, per the schematics. Have fun!

[DanGT4]

Capacitors don't have an anode end they are + or - , though most on speedy are not polarised.
I would cross reference to the schematic to confirm any components that I am unsure of tbh.

Actually they do, the + is the anode, - is the cathode, with a dielectric in-between. This spanner monkey knows perfectly well if you hook them up the wrong way round on a tantalum the electrical pixies get grumpy and let the magic smoke out.

I'll refer to the schematic and report back.

[DanGT4]

I checked out the schematic and PCB at lunchtime and can confirm that the long offset line indicates pin 1 end for the chips, and the closed end of the box is the + / anode for caps and diodes.

Now to get the bugger built...

[turboedge]

Hey Dan,

The line on the polarized capacitors and diodes go inside the boxes on the PCB, and the long line on the ICs is in-fact for pin one.

Happy soldering, Weaver

[DanGT4]

Hey Dan,

The line on the polarized capacitors and diodes go inside the boxes on the PCB, and the long line on the ICs is in-fact for pin one.

Happy soldering, Weaver

Thanks Weaver, for curiosities sake, is that a standard convention? I used to work at an electronics company and showed the board to a few of the PCB design engineers who said that isn't how they would indicate that info on the board. I'm not sure if it 's a convention thing between the UK/Europe/US/ROW?

Thanks again,

Dan

[turboedge]

is that a standard convention?

Not sure. Every EDA tool worth anything has a pile of standard footprints that you can use, especially for things like resistors, capacitors, and diodes. In this case the people who make the footprint libraries for KiCad came up with them. One of the benefits of these designs is that even with the part soldered in place you can still see the markings on the boards and easily verify that the part is oriented correctly. Some others that I have seen cover the orientation markings with the part, making that sort of checking more difficult. KiCad is opensource and it is constantly changing (hopefully improving), along with that there have been changes to the libraries as well. More consistent naming, sizing, and tweaks to help make sure re-flow soldering goes off without a hitch (especially important with the really small parts).

Thanks, Weaver

[DanGT4]

Thanks for the explanation Weaver. As I said previously, I'm a mech eng, so this is a strange and mysterious world to me, that I'm keen to learn about!

Well, the good news is I've built the ECU, and all appears to be working through the engine simulator, with no magic smoke or whizzy bangs. Now I just need to finish building the car that it's going in...

Thanks again,

Dan