Re: Building a phone ringer control for theatrical use

"Tuner" <tuner@[EMAIL PROTECTED]
> wrote in message
news:t7CdnTsUB_uJRV7YnZ2dnUVZ_q-vnZ2d@[EMAIL PROTECTED]
> I'm attempting to construct a control box into which 6
> separate phones will be connected with normal RJ11 jacks.
> I'd like to control each phone's ringer separately - no
> voice line, just make the phone ring.
> These will all be standard desk telephones, US issue.  I
> understand that I need approximately 90 volts AC to drive
> the ringers, but I can't seem to find out the required
> amperage so I can purchase the appropriate transformer. Is anyone
familiar 
> with the particulars?

One of the relevant particulars is that ringer voltage is not 60 Hz AC
power 
line voltage.

"According to AT&T, the ringing signal is an 88v 20Hz A.C. signal 
superimposed on 48v nominal D.C. supervisory voltage. However, the actual 
ringing signal used can and does vary greatly from one location to
another."

The original source was a hand-cranked magneto-like generator. If you can 
scrap one out of an old crank-operated phone - good for you!

Built-it-yourself info: http://www.techlib.com/electronics/telephone.html