[GreenKeys] Current loop to RS-232 converter?

[Mike Douglas]

Here’s one for the Model 33

https://deramp.com/tty_adapter.html

Mike D

> On Oct 14, 2026, at 8:58 AM, Charles Morris via GreenKeys <greenkeys at mailman.qth.net> wrote:
> 
> Is there any inexpensive current loop to RS-232 converter available? I
> used to use one of my 33 ASR's with a PDP-8 which I've since sold, so no
> longer need current loop. My other retrocomputing hardware is
> sufficiently modern  😉 that RS-232 interfaces are all I need.
> 
> I could build one by hand, but I'm feeling lazy ;) Vince Slyngstad and I
> designed and built a PC board years ago, which is still running in the
> other 33. The expensive part of that one was the small DC-DC converters
> to run off the 48 volt TTY internal supply.
> 
> The prices for off-the-shelf interfaces today are astounding, in the
> neighborhood of $150-200! Forget that.
> Anyway, suggestions welcome.
> thanks
> Charles
> 
> 
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