[PLUG-TALK] Rebuilding Teletype

[Pete Lancashire]

A teletype uses a constant current interface. modern ones when the circuit is
closed is 20mA older ones 60mA. Open circuit voltage in not too critical but
a reasonable value is 24 to 110 Volts. It can be lower but has issues.

Going from a 20 mA current to say a RS-233 value is pretty easy to translate
zero current <-> -12 Volts (well 5 nowdays but not really RS-232) and 20 mA
<-> +12 Volts.

Once you have the RS-232 for a PC you use a Serial Port, or I guess now days
a USB<->Serial chip :-)

Tell the serial port driver 110 Baud for a Model 35 and your making noise.

For me, I think a HP-211x minicomputer running timeshare Basic so I can
dig out my Star-Trek tape from 1972 or so load and and run it ...

-pete

PS http://www.dunnington.u-net.com/public/startrek/STTR1



On Wed, Jul 28, 2010 at 11:11 AM, Rich Shepard <rshepard at appl-ecosys.com> wrote:
> On Wed, 28 Jul 2010, Pete Lancashire wrote:
>
>> I'm rebuilding/restoring a Teletype ASR35 and just want to ask if there is
>> anyone who has a model 28 or 35 printer laying in a garage or shed before.
>
> Pete,
>
>   I've not worked on a TeleType terminal since 1973 when those were hooked
> to the DEC/System 10 at the Univ. of Illinois! I think we had the model LA-1011
> or something like that.
>
>   What will you hang off the end of the unit's cable when you're done
> restoring?
>
> Rich
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