Quote:
Originally Posted by russell_w_b
For less than two telephones, I would forget the resistor anyway - I've always found they work without! If you live near an exchange, this may well hold with four.
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The distance from the Exchange will have some effect on ringing current and subsequently available REN.
In the days of hard wired telephones the bell coils were 1K impedance and were wired in series, with a recommended maximum of six in total on any circuit (I use the term circuit as this encompasses the anomalies experienced with shared service or certain extension plan working) so based on that recommendation, in theory, you should be able to get away with a REN of six without using anything like a REN booster.
It may be, however, that the (presumably electronic) ringing generators used in modern exchanges don't quite have the current to offer that the older mechanical ones did which is why the REN was reduced to four.
One other thing to beware of is the fact that not all types of ringer will operate correctly together on the same line, this is mentioned in a lot of early BT instruction manuals after the event of the "Plug and Socket" system; An inductive ringer, such as a bell motor, and a Capacitive ringer, such as a tone calling device, may if connected to the same line, act as a notch filter at ringing frequency and effectively sink the ringing current causing poor or no ringing.
I have to admit that I have never experienced the effect in practice but can see that it could be possible.
Andrew