[GreenKeys] Teletype Model 15 power Q's...

Tue Nov 8 22:58:32 EST 2016

"yes  this is called a loop supply  normally  660 mils at  120 volts  but
for  local loop  less can be used"

I know this was a typo, but I do feel the need to correct it, as the OP is
a newb to this stuff.

The standard data loop for older TTYs (M15 included) is 60mA @ 120V DC.
This is most easily accomplished with a ~100mA 120V DC supply, in series
with a 2K 20W resistor. But this is the loop supply for +long+ loops - as
in, cross-town or even cross-country. You can xmit TTY data for several
miles on a 120V / 60mA loop.

For local use, 12-24V DC, limited to 60mA will do the trick. So at 12V use
200R 2W, for 24V use 400R 3W.

On Tue, Nov 8, 2016 at 9:50 PM, Ed Sharpe Archivist for SMECC via GreenKeys
<greenkeys at mailman.qth.net> wrote:

> sorry  sent this when it was not  finished it was  caught in the que
> looks like you  got answers disregard this  ed
>
> In a message dated 11/8/2016 8:48:48 P.M. US Mountain Standard Time,
> greenkeys at mailman.qth.net writes:
>
>
>
> In a message dated 11/8/2016 2:19:41 P.M. US Mountain Standard Time,
> hanyou at xsmail.com writes:
>
>
> Hi all,
>
> First, I apologize if I sound simplified in my questions ;o … I’m kind’a
> still a novice when it comes to circuits ;p (even though I am a ham -
> general license)… but just want to make sure I have a few things straight
> before I fire up this Teletype Model 15 that I have - that I got a couple
> of months ago :) ~...
>
> First of all, I’ve been having trouble finding out how the Model 15 is
> powered ;o .  I’ve gotten bits-and-pieces from various people on how the
> machine should be powered, but nothing definitive ;o .  So my questions :) :
>
> 1.  I understand that this machine requires both AC and DC power.  Are AC
> and DC power on separate circuits within the machine?
>
>
>
>
>
> 2.  Do I run AC and DC power simultaneously or separately?
>
>
> ac   for the  motor  etc
>
> the loop is  dc
>
>
>
>
> 3.  One person has told me that in order to use it in “typewriter mode”, I
> would need a DC power supply running at about 24-30vdc in order to activate
> it.  I would also need AC power, correct?
>
>
>
>
> yes  this is called a loop supply  normally  660 mils at  120 volts  but
> for  local loop  less can be used
>
>
>
> 4.  I do have a variable-voltage transformer… do I need anything special
> in-between the transformer - like fuses, diodes, etc ;o ?
>
> no  there is no isolation  use  with an isolation transformer  for safety
>
>
>
>
>
> 5.  If AC power is required with DC and while running in “typewriter
> mode”, the machine receives the 60ma loop current through the 120vdc
> dedicated power connector, correct?
>
> 6.  When running off of they line-in (data), the 120vdc 60ma loop current
> comes from the data line and not the dedicated DC power line, correct?
>
> 7.  What should I set the DC transformer voltage to ;o ???  I understand
> that the voltage requirement needs to be a bit lower than the 120vdc
> specified.
>
> 8.  When rotating the machine 180°, there is a part that has two wires and
> a few bars (sorry, I’m not sure what this part is called) on the base of
> the unit - right-near side… similar to what one can find in an old, rotary
> telephone (in a telephone, it opens and closes the telephone circuit when
> pressing / depressing the hook on the telephone).  This teletype has the
> two wires cut from it and I can’t find any documentation on this part ;o …
> what is it and is it critical ;o ???
>
> 9.  What can I use as a substitute oil plug on the main shaft ;o ???  Mine
> is missing ~o~; ~…..
>
> I’m sorry if some of these questions overlap ;o … I’m just trying to
> exhaust all of my questions and possibilities - to understand everything
> before doing anything further :) .  For reference, I have three lines/power
> lines going into the machine.  An AC power line going to terminals 21, 23
> and ground.  Dedicated DC power line going to terminals 24 and 25.  Data
> line (red jack) going to terminals 32 & 41 with a wire connecting terminals
> 32 & 42 together internally… not sure how this wiring on the data line
> effects things ;o .  The motor its 120vac synchronous.
>
> Anyways, simplified explanations please xD hahah - I sometimes can be
> kind’a dense ;p ~o~; .  Thank you so much in advance for all of your help -
> I really want to give this a thing a try ;D !
>
> Cheers ^^ !!!
>
> Sincerely,
> Eric ^_^
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