[GreenKeys] New USB to current loop driver board

[Pete Lancashire]

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.



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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