The metal fenceposts actually have a fairly low resistance. Unfortunately they're also pretty much grounded...
--
Grant Edwards grante Yow! I\'m ANN LANDERS!!
at I can SHOPLIFT!!
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This is the 6th grade Phun with Science level explanation; one you might see in what I called "Popular YuckTronics" magazine.
If you look at my origianl query, you can see I was addressing the far less obvious issue of getting enough power down the far-from-ideal line to run the ringers. THAT is what I still seek insight into....
[and why I x-posted to s.e.d...]-- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433
An old Kellogg 2554 I had in the '80s had a ringer equivalence of 0.7B.
With something like a Zaptel card and Asterisk, would there be a way to measure what the FXS module is sending to the set? In time, I can measure my 302 set that way.
-- Curtis R. Anderson, Co-creator of "Gleepy the Hen", still "In Heaven there is no beer / That's why we drink it here ..." http://www.gleepy.net/ mailto:gleepy@intelligencia.com mailto:gleepy@gleepy.net (and others) Yahoo!: gleepythehen
And here's a shot of the Morris 500 set. I note the horn style speaker and the vents cut into the side of the case.
I haven't read the entire thread so this may not be new to you.
Without knowing more about the particular ringer you have in mind, I can only generalize.
FCC requirements, and those of the Standard, ANSI T1.401-200? prevail and provide some insight. My T1.401 copy was issued in 1993, but likely still valid for this subject.
When a Central Office puts an Alert (the ring signal) on your phone line, it has both a DC and an AC component.
The DC is typically 52 Volts, but may be higher or lower, but in any case it has nothing to do with ringing your bell. It is used to determine if your phone has gone off-hook indicating you answered your phone. This is really a safety feature so you don't get that loud ring in your ear.
The AC ringing voltage, nominally 105 VAC, rings the bell. At the time my copy of the Standard was issued there were 13 possible ringers, itemized by their intended use frequency (between 16.6 Hz. and 66.6 Hz.), still in use in the USA.
This part applies to a phone having an AC determined REN of 1: If you have a Bell System type phone/bell, just to get you in the ballpark, you can assume 20 Hz. Typically the ringer impedance (including the DC blocking capacitor) will be about 40,000 Ohms, so ring current will be about 3 mA. As you can see, it won't take much of a husky ring supply.
I hope this helps.
Don
If I recall correctly, a REN=1 has an effective impedance of about 8,000 ohms which results in about 1W of power. This is what we used to estimate the ring generator requirements for the PBX that I used to work on.
I'll see if I can find the Bell Pub that gives the formula for calculating the ringer equivalence number, but I'm pretty sure that 1W for a REN of 1 is about right.
Bob
Nah... should have been VT52 terminal bell... er Buzzers.
Bill
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Besides, I thought that *was* country music.
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That shows what little you know about music.
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...
My query stems from the dim neurons of my brane. It was about the issue of getting enough power down that long R-C filter [...called the local loop...] to power the multiple ringers in a house.
It had nothing to do with saving CO ring suppy power. Before SubCycle's became SOP, She used to have big honking 48VDC->120V 20Hz motor-generators in the larger CO's and various uglyness in smaller ones. Not even a anal beancounter could find that load midst a large panel or step installation.
There was some very clever aspect of the whole design of the ringer magnetics that solved the issue. THAT's what I'm interested in learning about.
-- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433
Well, the standard bell must have been tuned to 20hz, thats just good power economics, and it would not respond to transients, or 60hz pickup. With a standard 2 on 4 off cycle, I bet that one third of the bells all rang at the same time. Just to keep the load on the generator constant. Note that a party line would have bells tuned to different frequencies.
TerryS
Any idea of why these specific frequencies >
TerryS
Nope, the standard ringer is not tuned to 20 Hz. It responds {at least} to 30 hz and other frequencies, can't recall how low...
Again, generator load is not relevant to my question...
And BTW, Ma never used frequency selective ringing; only independents did.
(Another poster asked "Why 20 hz?" and I echo that question...)
-- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433
I heard those were annoying. The Volker-Craig VC404 had an annoying beep as well.
-- Curtis R. Anderson, Co-creator of "Gleepy the Hen", still "In Heaven there is no beer / That's why we drink it here ..." http://www.gleepy.net/ mailto:gleepy@intelligencia.com mailto:gleepy@gleepy.net (and others) Yahoo!: gleepythehen
Not all party lines used tuned ringers. I don't think any significant number of Bell offices did. Party lines were served by using combinations of putting the ring on either the Tip or Ring wire to ground, along with a positive or negative DC voltage. This is called Divided Ringing. If you had a four party line you only heard your ring. If it was eight party, you heard your ring code and one other.
No, except there is an advantage in keeping the frequencies low; less line loss. And 13 is a huge number of options. I don't know how many frequencies might have been used in a particular type of office; it wasn't important to the Standard. There had been two other frequencies, but they were retired by the time the Standard was written.
Speak for yourself.
Mine has a sticker on the bottom that says says: BELL SYSTEM PROPERTY NOT FOR SALE and another that says: Sold by: Pacific Telephone Jan 09 1983
It has a dial too.
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hz and
Including 60 Hz.
That Big Honking motor generator, or whatever it was you called it, not only generated a continuous supply of 20 Hz ring voltage, it also (as I'm sure you well know, David) drove an "interrupter", and various different lines that were ringing at any given time would be supplied by different contacts on the interrupter, which did tend to equalize the load cycle.
I don't remember ever seeing anything definitive, but what your original post described did in fact sound like Larry Lippman or maybe Al Varney. It used to be really interesting reading what they had to say...
My understanding is that the 20 Hz ring current originated with the hand cranked magneto system. It was simply a case that hand cranking generated about 20 Hz (and obviously was not necessarily 20 Hz, hence a frequency selective ringer could not possibly have been used). They generated 50-70 VAC.
Larger switchboards would have had a motorized ring generator, even when magneto phones where in use. That of course became standard with common-battery and automatic switching systems.
But there are some other odd things that might be what you remember. Long distance lines and telegraph lines required some special consideration. 20Hz doesn't travel well over a long line, does not survive any sort of a repeater.
There originally had been 135 Hz ring systems between offices. Those also do not travel well, but when used with a repeatered system, every other segment could be
20 Hz and the ones in between 135 Hz. In that way it was possible to build a repeater that could pass signaling.Carrier systems made that unworkable too. The first signaling to replace 20 Hz and 135 Hz for carrier systems was 1000 Hz signaling. That was followed by a number of things, mainly selective signaling (SS-1) that used two tones, and eventually the well known 2600 Hz (and less known 2400 Hz) Single Frequency (SF) system.
The ringers for party line use were interesting too. A standard ringer could be any of 1) across tip and ring (single party line) or 2) from tip to ground or 3) from ring to ground. The last two obviously allow two ringers on one line, for two party service.
But a "biased" ringer was also used. It had a spring that pulled it to one side, and would respond to AC, but with "pulsed DC" (for example a line with 52 VDC loop voltage on it and superimposed AC ring current) it would ring only if the polarity of the line was correct. A two party line would use two of them, and at the CO the line cards would be connected to the same line, but one of them would be reversed tip and ring, and in the field the phones would be wired with the same turnover. The two systems could be combined to provide 4 party service, with two biased ringers across the line and one each from tip and ring to ground.
-- Floyd L. Davidson Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
OK. It was hard to tell from the post to which I responded: "If you look at my origianl query, you can see I was addressing the far less obvious issue of getting enough power down the far-from-ideal line to run the ringers. THAT is what I still seek insight into....">
You are generally correct, but we did own a few. There were occasions where a Regional Bell company and an Independent would trade operating areas, including ALL plant in place. Until the central offices could be upgraded, we had a variety of mechanical offices.
The answer is, in part, the ringer has a relatively high impedance such that each REN=1 ringer will draw only 3 mA. And, of course, the low frequency of the ring frequency is the other part.
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