11 Oct
2003
11 Oct
'03
5:19 a.m.
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/
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Email: waltje(a)pdp11.nl BUSSUM, THE NETHERLANDS / Sunnyvale, CA, USA