[HomeBrew] Teletyper to ethernet current loop interface.

[Håken Hveem]

Because there is a network of old TTY machines running over phone lines, 
so a internet variant will be nice.
there is some info here:
http://www.teleprinter.net/txp/english/telexnetz.shtml




Steven Weber wrote:
> ** Please do NOT cross-post messages when posting to HOMEBREW **
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>   
>> Hi, is it possible to make a unit that has full dublex loop current
>> interface with a interface to LAN/ethernet with internal ip adress and a
>> suitable tcp/ip port?
>>     
>
> I would think its possible, but why?
>
> For the loop interface, all you'd need is some opto-isolators and a constant 
> current source. Speed would be limited by the speed of the opto-isolators 
> and the length of the cable.
>
> Current loops are usually used in industrial applications where noise is an 
> issue and run at low speed. 4 to 20 ma current loops are used for 
> instrumentation. Old mechanical teletype machines used current loops as they 
> worked with switch contacts and relays.
>
> KD1JV 
>
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