[GreenKeys] New USB to current loop driver board

[drlegendre .]

Is there an old-fashioned schematic in those files? Nothing is popping out
at me.

On Mon, Dec 4, 2017 at 11:36 AM, Steve Garrison <steve.n4tty at gmail.com>
wrote:

> 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.
>
> I'll try to send a picture later of Nagle's new device alongside my cabinet
> it replaces.  Quite a difference in size and weight.  And overall cost
> savings as well since I did my cabinet through Front Panel Express.
>
> Thanks John for a wonderful project.
>
> Steve G./N4TTY
>
> -----Original Message-----
> From: greenkeys-bounces at mailman.qth.net
> [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of John Nagle
> Sent: Sunday, December 03, 2017 9:55 PM
> To: greenkeys at mailman.qth.net
> Subject: [GreenKeys] New USB to current loop driver board
>
> I've designed and built a new board which will drive a 60mA current loop
> Teletype from a USB port. This board requires no external loop supply; it's
> powered entirely from the USB port.
>
> It fits in a small case 75mm x 125mm.  There are two 1/4" phone jacks for
> keyboard and printer, a mini phone jack for a motor power control relay
> (5V,
> 100mA max) and a micro-USB connector.  Controls are an on/off switch and a
> BREAK button.  A 3-high LED indicates Power On, Motor On, and Data to the
> printer.  That's it.  Output current is regulated and will work from 55 to
> 220 ohm loads with no adjustments.
>
> Steve Garrison just built up one of these boards, and it worked for him.
> So
> now I'm releasing the design for general use.  Here are all the project
> files and documentation:
>
> https://github.com/John-Nagle/ttyloopdriver
>
> The Gerber files and drill files for fabrication are in
>
> https://github.com/John-Nagle/ttyloopdriver/raw/master/board/fab/fab.zip
>
> Send that to a board house if you want boards. I use Seeed in Shenzhen.
> They charge $20 for 10 boards, plus shipping, which is about $30.
>
> This is a moderately advanced surface mount soldering project.
> You'll need the tools and skills to solder 0.5mm pitch parts.
> Parts cost not including the board is about $50 per board.
>
> Usual questions:
>
> - Can you buy a completed board? Not from me. If someone else wants to,
> it's
> all open source.
>
> - Will you modify this to do ...? No, but you have all the design files in
> KiCAD and can do it yourself.
>
>                                 John Nagle
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