Just to clarify on the loop I’m referring to. There is a way to signal with lower voltage and use some capacitance for the kick to make the selector magnets work well enough that way… and it’s a perfect project still for a m15 terminal!

-All points on what voltage  is supposed to be absolutely accepted and I have learned a lot today. Thanks for this!


Mike is totally clear it’s limited to basically running a KSR and I thought I might plus that up.  I’ve stretched this concept pretty far beyond specs , and now think it’s about as far as I can take it.  

I may just scrap adding more to it and look for a terminal, made with a TTY loop so I can just play radio over the din of all my machines spooled up at the same time.  =)


Sent from my iPhone

On Sep 23, 2024, at 7:16 PM, Jim Cooper <[email protected]> wrote:

On 23 Sep 2024 at 18:29, Anthony Watson via GreenKeys
wrote:

What I need is something to take an anemic loop signal and feed my
patch panel itTMs spinach.

You should NOT have an "anemic loop signal" ...

As others have pointed out, as absurd as it might seem in
this day of nanoamps and 2v signals, Teletypes REQUIRE
60 mA of current, on and off keying.  And you can't get
away with a 5 volt supply that gives 60mA ...  look up
TIME CONSTANT in your basic electronics book ... you
will find that a 5vdc / 60mA circuit will not come up to
60mA in the time of one tty 'bit' ... you will never get good
copy with that.  

That, as strange as it seems, is why Teletype 'loops' use
a voltage source of around 100vDC and a big monster, high
wattage resistor adjusted to 60mA ...  "what a waste of
power into heat" you are thinking.  Right, but that's the
way it has to be ...  look up TIME CONSTANT in your
basic electronics book.