[GreenKeys] Loop supplies

[Paul Pennington]

Could someone post the Molex part number for the 15-pin plug to connect an
ASR-33 to a computer?

Paul Pennington
Augusta, Georgia

On Thu, Nov 1, 2018 at 5:37 AM Steve Garrison <steve.n4tty at gmail.com> wrote:

> I'll be using John's ttyloopdriver at my hamfest demo this weekend doing
> the TTY Texting.  With his older design in attendance as a backup.  Both
> devices work as advertised.
>
> As for difficulty of assembly, I had 3 of the smallest SMD devices
> soldered in place by a professional (she is a ham as well) and did the rest
> of the board myself.  The biggest drawback for some would be cost.
> Sourcing such small quantities of components from DigiKey, Mouser, and
> CoilCraft doesn't offer much in the way of discounts.  I thing it was close
> to $130.00 when all was said and done.  But IMHO, well worth it for a very
> small and professional looking solution.
>
> Thanks for all your efforts John.
>
> Steve G./N4TTY
> Sent from my iPhone
>
> On Oct 31, 2018, at 4:59 PM, John Nagle <nagle at animats.com> wrote:
>
> >> On Behalf Of W9DDD > Sent: Monday, October 29, 2018 1:59 PM
> >> Subject: [GreenKeys] Loop supplies or selector magnet drivers
> >> Wonder what people are using these days loop supplies and keying the
> >> loop or selector magnet directly.  I was thinking of going old school
> >> with 120 VDC and a series 2,000 ohm 10 watt resistor. But, looking at
> >> the prices for 10 watt resistors, I'm re-thinking things.
> >> I might get lucky with something already being in the LESU of the
> >> pending 28, but I'm not counting on it.  I'm trying to get setup so all
> >> I have to do is plug it in when the 28 arrives.
> >
> >    I've been down this road several times, as many of you know.
> >
> >    First I did a more or less traditional setup, with a 120VDC supply
> > and a 2K 10W resistor.
> >
> >   http://www.aetherltd.com/connecting.html
> >
> > These work fine. I've had two of them in use for almost a decade.
> > The 2K 10W resistor used is a strange thick-film device which can
> > be mounted on a PC board without scorching it, because it has so
> > much surface area.
> >
> >    Then, as a technical tour de force, I built a 120V 60mA
> > driver for Model 14 and 15 Teletypes which is powered entirely
> > from a USB port.
> >
> >   https://github.com/John-Nagle/ttyloopdriver
> >
> > It's the size of a cigarette pack and generates little heat.
> > It uses a custom-designed special purpose switching power
> > supply. No energy wasted in a big resistor.
> >
> > It's the ultimate solution to driving an old Teletype from
> > a computer. But it's hard for homebrewers to build.
> > It's all surface mount.  It has to be, or the switcher
> > wouldn't work. It's designed like a modern
> > production product, with protection circuitry and startup
> > power management.  This is how you'd do it if you were
> > having a thousand built in Shenzhen. But it's beyond most hams.
> > Steve Garrison has built some from this design.  I've built some.
> > But the market is too small for this to be a product.
> >
> >            John Nagle
> >
> >
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