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Old 9th Aug 2017, 12:06 am   #9
russell_w_b
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Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
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Default Re: REN, Resistors &c.

Evidently the European Telecommunication Standard REN is defined (REN 1) as a simulated ringer detector circuit consisting of a 55 H inductor in sries with a 7 kilohm resistor, and is based on the characteristics of the dynamic impedance of a type 59D bell movement.

From my extrapolation method described earlier I reckon the 59D (the one with the 4000 Ohm @ d.c. bell-movement) is 7186 + j8275, or a Z of 10960 Ohms at 25Hz, which near as dammit fits the spec.
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