Splitting off some bad advice

Splitting off some bad advice.

Dunno quite what you mean by this. There’s one 3.3 v pin, two adjacent 5 V pins and a sprinkling of ground pins around the connector. Can’t be too difficult.
Regard the ground pins as a friendly gesture to make your own layout easier.
And don’t fall into the “aesthetic” trap of making all tracks as thin as the PCB maker accepts (like 15 mil). Bad engineering.

You keep on giving advise that is simply faulty.
I had a look at that zero thing and it has two 3V3 pins .

What exactly is this “bad engineering” supposed to be?
And thinner tracks (for low current digital signals) are better, and this has nothing to do with “aesthetics”, but with lower capacitance, Both to the GND plane, and to other tracks. If you use a bigger clearance then there is less crosstalk.

And where did you get that idea of “making all tracks as thin as the PCB maker accepts” general advice is to keep some 20% to 30% above the limits of your PCB manufacturer. Tracks with a width of 0.2mm (8mil) is already plenty. But for a DIY project such as that Raspi zero project where this thread started it’s just not relevant at all and I don’t like that tread to get contaminated with a discussion like this.

So now the moderators are going to decide what is good advice and “split off” what they judge is bad advice?

This is a bad precedent.


Maybe so, but the last week I had two or 3 “discussions” with ml9104 where he just dumped some remark in someone else’s tread and which lead to unpleasant derailments.

And I agree, maybe I was a bit too quick doing this, but the thread it was posted in still has a link to this thread.

Another factor is I’m quite tired at the moment, this may have influenced my action too. So at the moment I’m signing off to lay an ear on a pillow, and I’ll see tomorrow what others think of this.

I believe that inductive crosstalk usually dominates at voltages less than maybe 50V or so. I actually did some pcb crosstalk measurements about 45 years ago. I designed a board with (I think it was 18 inches = 46 cm) of 0.2 mm spaced pcb track. I concocted an avalanche pulse generator to drive one track with pulses that were a few nSec wide. I observed pulses generated on the other track. It became evident that the dominant crosstalk was inductively coupled and not capacitively coupled. I think that this bit of information is consistent with most layout recommendations.

Wider tracks tend to have less inductance. Of course there may be more to this, such as varying track width but with a large constant center-center pitch spacing. There may be “too much of a good thing” so that it is better to keep significant distance rather than making tracks extremely wide.

I have experienced capacitive crosstalk on a pcb on one occasion when I was switching some relatively high voltage with an SCR and I had a track to a comparator input nearby.

Do like me. If in doubt or troubled, leave a reply or action 'till tomorrow.
There is no point in upsetting/alienating the denizens as well as the offender. :slightly_smiling_face:


Simple fix:
just redirect my posts to /dev/null
Issue solved.

That’s true, it should be possible to ignore a user:

This is not a recommendation to do that, though.

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