On Sat, 11 Oct 2003, Ian Primus wrote:
> > If you want to receieve also, you can use another transistor and
> > resistor to pick off the change in loop current that happens when you
> > press keys which open the loop, and drive the serial port.
> >
> > I've done one of these fairly recently, and if poked with a
> > not-too-sharp stick, I'll scan the schematic and pu on my website.
I found a 20mA interface schematic in my pile of docs.. I put it
up on
http://www.pdp11.nl/Hardware/20mA.pdf
Cheers,
Fred
--
Fred N. van Kempen, DEC (Digital Equipment Corporation) Collector/Archivist
Visit the VAXlab Project at http://www.pdp11.nl/VAXlab/
Visit the Archives at http://www.pdp11.nl/
Email: waltje_at_pdp11.nl BUSSUM, THE NETHERLANDS / Sunnyvale, CA, USA
Received on Sat Oct 11 2003 - 12:19:26 BST