[GreenKeys] Run teletype model 15/19 keyboard and printer on different circuits?

[Jim Cooper]

On 16 Sep 2025 at 21:41, Windows XD wrote:

> I was wondering if it would be
> possible to run the keyboard on a
> 5vdc circuit wired to said solid state
> relay and have the keyboard run on
> 5vdc and the selector magnets at
> 120vdc. I can't think of any obvious
> problems with running the keyboard at
> this lower voltage, but I'd like to
> be sure. 

The Model 15/19 keyboard contacts were not 
meant to be run on very low voltage.  There is a 
lot of oil and other contamination inside a 15 
housing which can get on the kbd contacts; the 
120v can 'break thru' that contact corrosion 
where 5v probably would not.  
> 
> P.S. My keyboard has arcing problems with the contacts, will this
> modification coincidentally also fix that?

There should be a module wired across the kbd 
contacts with a capacitor and resistor to reduce 
the sparking ... that may have been disconnected 
or even removed by a prior owner.