[GreenKeys] Interface board for Model 15, schematic and partslist (RO version)

[gil at baudot.net]

> -------- Original Message --------
> Subject: RE: [GreenKeys] Interface board for Model 15,	schematic and
> partslist (RO version)
> From: "Lester Veenstra" <m0ycm at veenstras.com>
> 
> Not enough power available on even a "spec" RS-232 to generate the 
> needed loop supply for the older machines - which need at least 60V - 
> 90V would be better.


Yeah Les, you can't power a loop, but you can usually draw enough power
from the 232 port for the interface, and key an external loop supply and
limit resistor, as in my old TAP.  This was the smallest loop keyer I
made, squeezed into a DB9 adapter housing:
http://www.baudot.net/gil/tty232-tap/TTY232_TAP.pdf

gil