[GreenKeys] New USB to current loop driver board

[epvgk at limpoc.com]

On Tue, Dec 05, 2017 at 10:49:55AM -0800, Pete Lancashire wrote:
> Seeed has become my primary source for boards. Just had a run of 4 layer
> boards done and they were as good as any others. A friend is soon going to
> try them for a 8 layer with blind vias.
> 

There are so many options nowadays. I have used OSHpark quite a bit,
mostly because they're ridiculously chip for tiny boards. Currently waiting
on a set from pcbway.com which had great pricing and good specs, and
no extra charge for things like odd board thicknesses and stuff. 

> 
> 
> On Dec 4, 2017 5:07 PM, "John Nagle" <nagle at animats.com> wrote:
> 
> > Q and A:
> >
> > On 12/04/2017 07:32 AM, Jack wrote:> Is a schematic somewhere in all of
> > the info? I can't find it.
> >
> >> Thanks, Jack K2TTY
> >>
> >
> > There's an image of the schematic at
> >
> > https://raw.githubusercontent.com/John-Nagle/ttyloopdriver/m
> > aster/board/ttydriver01.png
> >
> > if you don't want to install KiCAD.
> >
> > From jpruitt67 at gmail.com:
> >
> >> Can you tell me what size the board is? Jim Pruitt WA7DUY
> >>
> >
> > 75mm x 125mm.  I know there is a price break if you get below
> > 100mm x 100mm, and the board could be shrunk to that size.
> > All the CAD files are there if someone wants to do it.
> > I made it that big because it fits a stock enclosure.
> >
> > Steve Garrison <steve.n4tty at gmail.com>
> >
> >> Guys & Gals, this is a fantastic board, but is not for those with
> >> even a little fear of SMD assembly.  There are three chips that I had
> >> mounted by a profession SMD tech.  And there are a couple of tricks I
> >> stumbled over, so if you want to attempt one of these, get in touch.
> >> I may want to do 1 or 2 more of these for myself, so if any others
> >> are interested please get in touch as there is no reason for more
> >> than one of us to order 10 boards.  And I spent more than $50
> >> (including shipping and tax) for my parts since I was ordering for
> >> just one board.  Ordering for multiple boards could save a good deal.
> >>
> >
> > Fine with me.  If you want to do modern electronics, you have to deal
> > with modern SMT.  The good parts are SMT-only now.  The oscillator part
> > of this, around U1, only works properly with tight layout. Yes, this
> > means tweezers under a microscope.  I use a little USB microscope for
> > this, along with a solder paste dispenser and a reflow oven. Learning
> > SMT assembly takes practice. There are dummy practice kits you can buy;
> > they come with a board and some components that don't do anything.
> > I went through five of those before I assembled this board.  Also,
> > this is the seventh rev of the board; it took a few tries to get this
> > working properly.
> >
> > If there was a market for 100 of these, I'd have them made by Seeed in
> > Shenzhen, but it's too small a niche for production.  For production,
> > I'd reduce the board size, get rid of the daughter board and use a
> > CP2012N directly, and use smaller solid state relays, so the thing
> > could be assembled by a pick and place machine except for the connectors.
> >
> >                                 John Nagle
> >
> >
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