PowerComms v1.3.0 preview 2

here is the second 'release candidate' for the board. i did a bunch more work, incorporated a bunch of changes, and i think this one is pretty solid. i'd like to do one more revision to it, but that will be mostly cosmetic i think.

more info on changes here: [reprap.org]

edit: its also been checked into subversion. also, kicad libraries changed... update your versions =)

Edited 2 time(s). Last edit at 08/28/2007 10:05PM by Zach Hoeken.

What type are the power connectors? They look a bit small for the current involved.

I would have placed C7 above the regulator to get the track to pin 1 as short as possible. You could then move R2 to where C7 was.

The pitch for the resistors looks too small. I would use 0.4". The picture of the 1.2 board on the wiki shows the only resistor half in the air because it does not fit the 0.3" footprint properly.

---

[www.hydraraptor.blogspot.com]

the power connectors say 4.0A w/ 22AWG wire. hopefully that should be enough for us.

i put your changes on the TODO and i'll do them later tonight.

hm I may have commented on the wrong thread. How about 1 thread per Release candidate?

Not sure on the current rating vs what might be used. It is better to error on the high side. To be safe I would derate the spec for current handling by 50% (probably over-conservative but that also leaves room for growth).

yeah, sorry... i probably confused things by starting another thread. its probably better to have it all in the other one... use the other thread instead.

I am not too familiar with AWG but the wiki says 22 AWG is 7/0.25 wire. I would normally use 24/0.2 for this sort of current which is between 18 and 19 AWG. If we are assuming a couple of amps per motor then the table below suggestes we need 16/0.2 wire at least which is 20 AWG.

[en.wikipedia.org]

from [www.kpsec.freeuk.com]:
Typical specifications:
10/0.1mm (10 strands of 0.1mm diameter), maximum current 0.5A.
7/0.2mm (7 strands of 0.2mm diameter), maximum current 1.4A.
16/0.2mm (16 strands of 0.2mm diameter), maximum current 3A.
24/0.2mm (24 strands of 0.2mm diameter), maximum current 4.5A.

---

[www.hydraraptor.blogspot.com]

okay, so its obvious that the .100" headers wont cut it.

what is the best alternative? we could always switch to .200" standard terminal blocks, but then we lose the keyed aspect. is there a keyed equivalent for what we're using, but with a .200" pitch?

see molex connector post on the universal controller thread.

The type I had in mind was a 2-way one of these which is actually a 0.156" connector, Molex I think.

It will take up a lot less board space than disk drive connectors. I like to use connectors the correct size and make my own cables so they are the correct length but I seem to be in a minority here.

You have the choice of crimp and poke or IDC. Obviously the crimps are a lot bigger than 0.1" so less fiddly to put on if you don't have a crimp gun. IDC versions use a T-shaped tool, which although still overpriced is much cheaper than a crimp gun. I have known people make their own or you can do it with needle nosed pliers.

---

[www.hydraraptor.blogspot.com]

I've now constructed one of the PowerComms 1.3.0 board, and have three observations so far.

1) Everything fits where it should, logically laid out, happy happy.

2) The parts database should indicate five 1uF caps, (C1..C5), not four. (Thankfully I had one in the bin...)

3) The directions are still a "copy of PowerComms 1.2 as a placeholder, but PLEEEZE get the current 1.3 schematic linked in ASAP. At the absolute minimum, add text to indicate that the bicolor LEDs are D4 and D5, and two of the greens are D2 and D3.