6 Nov
2015
6 Nov
'15
5:11 a.m.
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
http://plymouthcolony.net/starcity/radios/index.html