Some PCB design ideas for DIY LDD-L driver based builds

[theatrus]

Thanks for the input!

I just noticed that JLCPCB is allowing other colors on the cheap board deals now, what color should we do on the LDD-H boards, and future runs of the LDD-L? I'm thinking either Blue or White would be a nice option, both look a bit nicer than green- and I'm partial to the White... I may switch to either on the next run of tube project PCBs too.

White is nice but also shows off flux residue nicely (and if it gets warm, will discolor)

 

[Macca_75]

Color doesn't matter to me - it's hidden

Any idea on an ETA with the LDD-H 8x will be available?

 

[Lingwendil]

Planning on finalising the design for each in the next few days

 

[Lingwendil]

Whew, just spent an hour or so going over both LDD-H boards, and think they're pretty much done. Just going to fix a few little goof-ups here and there with trace sizing, scoot some silkscreen notes around, and I think they will get files uploaded by the end of the day.




Still need a neat little logo of some sort, and I'm thinking of adding a weird little quote as an easter egg somewhere on the boards too

 

[SpringHalo]

Hi Lingwendil, nice work you're putting out so far. Looking over your 8UP-LDD-H board I'm concerned about the negative power input of U2, the bottom ground pour is pretty isolated by the PWM2 trace going out of the header. I suggest you make more liberal use of vias since they're free to use, and will let you keep your ground plane less segmented.

It would also be good for usability to separate the "PWM Inputs 1-8" label into individual text for each pin by rotating the text and putting it where you have "Pin1, Pin10 are GND" so you end up with:
GND
CH1
CH2
CH3
CH4
CH5
CH6
CH7
CH8
GND

Cheers,
Spring

 

[Lingwendil]

Great suggestions! I like the labelling scheme you suggested for sure, and silkscreen ink is free anyways. The less guesswork or separate documentation the better. I'll incorporate that for sure.

Also- nice suggestion on the ground plane. That's something that I didn't even think of. I'll have to add a ground pour (or large trace) and connect it with vias. Currently I don't have a top plane of any sort, so I can add something fairly easily

 

[Lingwendil]

That looks great, just changed both with the pin designations-



Also working on adding vias. For some reason I always forget that they exist



This should open up the ground plane a bit. Might pull a few other traces to the top plane as well to get the current paths a little more open as well.

 

[SpringHalo]

Looking much better. The PWM traces for U1, U3, U5, and U7 could also be routed on the topside from the 10K resistors to the LDD PWM pins, without even needing to use vias.

 

[kegler]

I like the changes.

Is there a reason for the pin function name orientation being reversed from the rest of the labeling?

On the LDD/SCW joint use locations - I think it would be a clearer to have dual labeling placed inside the component outline. The 4up does not have a separate designation for the SCW while the 8up does. Also I think U9 & U10 locations are inverted on the 8up - does not follow the pattern set for the LDD's.

For the 4up:
U8 - LDD/SCW
or
U8/U10 LDD/SCW

For the 8up:
U7 - LDD/SCW
U8 - LDD/SCW
or
U7/U9 LDD/SCW
U8/U10 LDD/SCW

I think it is clearer for the location to have a single name, but with two different components that can be installed there.

I plan on using machine sockets (as I believe you are, I think I remember reading somewhere here). I want as good a connection as I can get, as some of these pins may be carrying more than a trivial current. And I hate de-soldering this type of component just so I can swap them out ...

 

[Lingwendil]

Pin function being off is an artifact from changing parts outlines early in development, I had an issue with the first one I used, so I pulled them and ended up witht he new model having the silkscreen upside down... I just never got around to changing it until now. Should all be in the correct orientation now.

Yes, U9/U10 were swapped, I ended up changing the parts names a bit to clear things up.

I also re-routed some PWM traces to the top of the board, the ground plane is more complete now.

 

[Lingwendil]

And here's the 4up-



Y'all think we should use "LDD1, LDD2" type of parts names, rather than the traditional "U1, U2" scheme that's usually used with ICs? I think it may be a bit more intuitive for non-electronics types.

 

[kegler]

Looks great!!!

One more small request.

On all the topside "Ux" components label pin 1 with "1".

On the reverse side also label pin 1 with "1" and place a "Ux" label in the center of the component location. No outline needed. Also it would be nice to have the pin function names on this side too. With components in place the topside labels are not going to be visible.

Saves a lot of mental gymnastics when troubleshooting and going from one side of the board to the other, while looking at the datasheet's bottom view. While experienced builders may not need this, the novices will certainly appreciate it.

 

[Lingwendil]

Nice suggestions for sure- saves a bit of fuss so definitely worthwhile additions-



(note the updated power traces and revised PWM routing)

Adding them to the 8up now.

 

[Lingwendil]

And updated the 8up with the new silk too-

 

[kegler]

Wrong end for Pin1. Should be on the component input end at -Vin. Probably should mark Pin24 too since ink is so cheap.

Also, use the datasheet's pin function names (ie -Vin, +Vin, -Vout, +Vout).

Otherwise you got what I was looking for.

 

[Lingwendil]

OH BOY!

That was a huge brain fart

Yeah, wrong pin! I'll change it now

 

[Lingwendil]

Okay, got that all put in, fixed the pin location, and scooted some labels around-



Both boards are updated with the changes.

 

[kegler]

That looks better, except for U2 (still wrong end)

But this is the advantage of open source - the more eyeballs, the less likely an error will slip by.

This labeling would be overkill for a commercial product, but for DIY projects it is a necessity. I like to get even the newbies looking at the datasheet. It contains a wealth of information that will only help their understanding of a given component/circuit. No need to be intimidated by it.

Time for others to weigh in.

 

[Lingwendil]

Ah, missed that one, must have accidentally un-selected it somehow (Its been a very long day) as I'm doing this on a laptop with a tricky touchpad

A second set of eyes is really helpful here! Especially all the suggestions- this is intended to be a community owned project, clear labelling is a huge benefit

 

[Macca_75]

Being one of the above menitoned "non electronic type" who is capable of soldering and little else, maybe inking a "box" around where each socket is on the Bottom of the plate (similar to the top) may help - as mentioned once populated you loose access to any of the top data.