wb8foz@mthvax.cs.miami.edu (David Lesher) (03/27/91)
{likely more than you even wanted to know;-}
Well, I dug out a ten + year old North Supply book, and here's what I
found. There were lots choices in ringers, all basically with this
scheme:
Untuned:
Straight Line 5900 ohms
Straight Line 1000/2650 ohms
Tuned:
Harmonic: 16.66 hz
25.00
33.33
50.00
66.66
Decimonic: 20.00
30.00
40.00
50.00
60.00
Synchromonic: 30.00
42.00
54.00
66.00
{whew..}
A few thoughts/questions: Who used what scheme? I sure would not want
to be the poor guy with the 60 hz assignment - I'd expect a problem
with falsing. There's no mention of 'tuning' these with different
caps. There was a different listing that did enumerate capacitors of
different values, but it was not clear that one could retune a ringer;
rather it appeared that ringer X needed cap x, Y needed y etc. But I'm
likely reading between the lines too much.
So there were {at least} the following selective ringing methods:
Bell 2 party {ring to ground, tip to ground}
Bell 4 party {above, plus superimposed DC block/pass}
Harmonic
Decimonic
Synchromonic
3 longs and a short [Hey, that's us!]
wb8foz@mthvax.cs.miami.edu (305) 255-RTFM