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
