Teletype services

Dale H. Cook radiotest at
Fri Nov 6 07:11:14 CST 2015

At 04:12 PM 11/5/2015, Tony Duell wrote:

>... it's things like the power supplies, ringing generator, etc that are the major part of the work.

Those are actually pretty simple for someone with sufficient analog experience. The reasons why I designed and built my own system are:

1) I am semi-retired and have more time than money.
2) I had everything I needed in-house except for the call-progress generator IC (which was easily obtained).
3) I enjoy designing and building equipment, though this is my first dedicated processor build in more than 20 years.

>The ringing voltage in particular is a pain, it's AC, and at a fairly low frequency (16.67Hz to 25Hz depending on country).

In the US the Bell standard is a 90 VAC sine wave at 20 HZ with a cadence of 2 seconds on and 4 seconds off. I work only with US equipment so I only have to meet Bell standards.

Dale H. Cook, Roanoke/Lynchburg, VA
Osborne 1 / Kaypro 4-84 / Kaypro 1 / Amstrad PPC-640 

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