Pinout for current loop interface

Nigel Johnson nw.johnson at
Sat Aug 17 14:00:32 CDT 2019

You haven't lived until you have played with live long-line teletype 
current loop circuits. In my first job as an FE on a Univac that was a 
store and forward message switcher, we had racks of mercury relays 
feeding the teletype lines, which ran at 130VDC to give the current 
needed to get to the next hop! Working in that rack could result in some 
very sudden surpsies!



On 17/08/2019 14:50, Charles via cctalk wrote:
> In my prior life as an EE, I had to do it many times (early 80's)... I 
> may be nostalgic, but not THAT nostalgic :)
> -----Original Message----- From: Chris Hanson
> Sent: Saturday, August 17, 2019 1:37 PM
> To: Charles ; General Discussion: On-Topic and Off-Topic Posts
> Subject: Re: Pinout for current loop interface
> On Aug 17, 2019, at 9:14 AM, Charles via cctalk 
> <cctalk at> wrote:
>> I just hate having to make a custom cable for every terminal and 
>> computer I
>> own or work with ;)
> Ah, but isn’t doing what so many before you have had to part of the 
> charm? :)
>  -- Chris
> ---
> This email has been checked for viruses by Avast antivirus software.

Nigel Johnson

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