The REN definition is in FCC Title 47 part 68 (aka FCC part 68). Look at the section "Ringer Equivalence Definition" on page 336.
For a 20Hz ringer, the minimum ac impedance for REN=1 (what they call "N") for a loop start line is 7000ohms.
The 3mA you were referring to is the maximum dc current that can flow during ringing, but the ac current is much higher.
Bob
hz and
The party line system installed in my grandparents' farm just rang every phone in the valley, but with coded rings (one long, two short, etc).
You're right, thanks. I see where I went astray. My eyes aren't up to reading that hard copy fine print any more.
So if we assume 130V of ring voltage we're looking at about 19 mA of 20 Hz. current.
Sorry for the confusion on my part.
...
That was very common, though I don't know if Bell System companies did it or not. When I was in grade school our phone was two shorts, but that was an independant telco, not a Bell operating company. I'm pretty sure that they also used at least one of the above systems and that we did not hear all of the rings. If I remember right there were something like 16 parties on a line...
-- Floyd L. Davidson Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
Even into the 50s there were manual Bell offices.
As I recall, by the end of the 50s there were Independent Company Offices (ICO) that even had their own AMA via their Stromberg X-Y offices, before some of the Bell offices had CAMA in their SXS offices.
The ICs were motivated to upgrade their offices by very affordable government loans. The scale of Bell upgrades was so great there wasn't enough money or manpower to properly meet customer service needs, muchless to relatively keep up with ICO upgrades. In 1956, Pacific Telephone Northwest was split off of PT&T primarily so we could raise Capital to meet our needs. At that time we still had some manual offices. It was sure fun....
Agreed. Lots to learn from them.
BTW, I chatted with Al ~5 years ago...
Things I never knew; thanks. I recall Lorain Products Loop Extenders that did weird things re: ringing, but not what they did.
-- 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
After a little internet search, I found this old telephone directory page from Waitsfield and Fayston Telephone Co. in a genealogical site.
The numbers are listed by "line" and "ring". Note the broadcast rings at the top of the page. The line through N. Fayston is line 16, the one I remember.
So if you have 3 ringers in parallel on a 5+ mile [26Kfeet] loop, you have a damn good voltage divider. Now, take ten miles.
I seem to recall Al saying the longest loop found in a survey was
100Kft. Gulp.-- 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
snipped-for-privacy@apaflo.com (Floyd L. Davidson) hath wroth:
hz and
20, 25, 30, 60Hz +/-5%. I have a telephone line simulator/tester that will do all of those:Well, I had one, as I loaned it to someone and forgot whom.
There are more frequencies available:
but I don't think Ma Bell ever used selective ring. As I recall when I worked for Ma Bell in the late 1960's, there was only one "ring bus" on the frame which was 20Hz. Incidentally, everyone got fried by the ring bus exactly once. "Harmonic, decimonic and synchromonic series ringing systems generally are employed in the telephone service industry. The harmonic series are 16.6, 25, 33.3, 50, and 66.6 Hertz. Decimonic series are provided as 20, 30, 40, 50 and 60 Hertz, while the synchromonic series are 16 (or 20), 30, 42, 54, and 66 Hertz."
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Yeah, according to FCC Part 68, the minimum total ac ringer impedance for a loop start (POTS) line is 1400ohms. I seem to recall that 1800ohms was the max dcr for a loop. So, yes, that's a nice voltage divider.
Part 68 also says that the minimum ring gen supply voltage might be 40Vrms (I remember 65Vrms from BellPub 48002 - but that's for PBXs). If the loop is
1800ohms and the ringer load (REN=5) is 1400ohms, that only leaves 17.5Vrms for the ringers worst case. I can't imagine ringers working down to this low of a voltage, so I would assume that on these long loops the telcos would limit the total REN to something much smaller than 5.Thank goodness ISDN became so popular and replaced most of our POTS lines. ;-D
Bob
You laugh but I talked a friend into ISDN. He's 41Kft out but it works 99% of the time, and is many dB quieter than his POTS. It was ...disquieting.. to call him from my 7507 as there would zero line noise and during pauses in conversation, you'd often think the circuit was dead...
-- 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
Don't you just *love* getting your arm jerked from here to there at 20 jerks per second! Makes the arm feel like it just ran a marithon.
I'm not sure about a CO, but in a typical long distance office the ring bus has no interrupter on it. Straight
105VAC at 20 Hz which doesn't stop and let you off every couple seconds... that is *nasty* stuff.-- Floyd L. Davidson Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
And then there were the 130VDC + and - battery Ttaps for the telegraph (TTY) testboard. Also Ouch.
Do you have any idea what the base frequency these are derived from. I cannot make the math come out. One tidbit I found on the net was why A & B RENs. An A REN is referenced to a electromechanical tuned ringer of 20 or
30HZ. And a B REN to the same of 15 to 68 hz, excepting 20 or 30.TerryS
"Terry" hath wroth:
Incidentally, did you notice that the patent was issued in 1985? That's because the old patent had expired and various people were repackaging old patents and repatenting them. The dead (technology) shall rise again. There's quite a bit in the background section, much of which I fail to understand.
It wasn't called a "ring generator" for nothing. (Not a "ring tone generator" which is something quite different). It really was a DC motor -> AC generator.
I have no idea if there is a base frequency for ringers. As I vaguely recall from CWT (Cal Drip and Tinkle) prior to when GTE bought them in
1967(?), they had party lines with seperate ring frequencies. I recall that they used a motor-generator that started at -48VDC, and fed several gearboxes with multiple generators attached to generate the other frequencies. However, I don't recall what it looked like. I tried to find a photo of the contraption online but couldn't. I may have something in some old BSP's.Also, as I recall, selective ring didn't work with the later Model 500 phones. It only worked with the WE 300 party line series ("lift plunger to dial or talk") such as:
There were some Model 500's that worked on party lines, but they were not the selective frequency ring flavor:
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
snipped-for-privacy@apaflo.com (Floyd L. Davidson) hath wroth:
I still remember it today. It was a rite of initiation at the CO. Everyone that worked on the frame had to get zapped at least once or they were reviled as being excessively careful. Those that got zapped more than once, were deemed excessively sloppy. I'll confess to getting fried twice, once while on a ladder. Incidentally, this was in the daze before everyone wore helmets so I managed to bounce off the rack a few times before hitting concrete. Ouch.
Yep. Continuous ring. Great way to identify the line and drive the customers nuts. Apply continuous ring to their line and go do something else for a while. After a few minutes, the test board would pass on a call that someone's phone was "stuck" in ring. That was sufficient to identify the line. The practice was officially discouraged, but still used when necessary. I also had a line tracer consisting of the guts from a ringer, the resonating capacitor, and the leads shorted together. There was enough inductive pickup to barely ring the bell by induction. That practice was also officially discouraged, but there were such ringers in almost everyone's tool kit.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
I thought that it was weird to see an electronic ring generator for sale in a local surplus store, while the local CO was still all mechanical.
-- Service to my country? Been there, Done that, and I\'ve got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
The party line ringer at my place was a seperate box with taps.
TerryS
Richard Henry wrote in news: snipped-for-privacy@x35g2000prf.googlegroups.com:
short,
We had a party line until 1980 or so, on our smallish independant phone company. By my time, I think it was only 2-3 customers per line.
The multi-grounding thing was used with the distinctive rings. I do know or old 500 wall rotary set was wired with a ground wire.
That ended in the 50s, when dial phones started. The old man doesn't remember those numbers, but has the same number they first issued with the dial phones.
A fair number of subscribers still had manual service even in the early 1960s. There was so much demand for new telephone service that dial offices needed expansion in addition to manual offices being converted. In addition, even those subscribers who had dial service many could only dial within their own community, any calls beyond their own C.O. required an operator until adequate trunk and tandem exchanges could be built. Another challenge was finding land to build a new dial CO. Bell System magazines from the 1950s show operators and service reps working out of temporary trailers and other like arrangements to meet high demand.
Still another problem in the 1950s was the Cold War and massive defense spending. The Bell System was a major military contractor, for both plain military phones and advanced fire control systems. A lot of Western Electric capacity was tied up on top priority military contracts in the 1950s. This became controversial in the later 1960s.
Whether an office was manual or dial did not affect party line service. Dial service, including ESS, had to provide for it. (In a number of states party line service is no longer offered at all, in a few others it is limited to existing customers.)
The last Bell System manual office was on Santa Catalina Island, cut over to ESS around 1980. The last major Independent manual office was gone a few years later, but some very isolated oddball small switchboards may still exist to this day or lasted until not long ago.
Party lines were once extremely common in cities as a way to save money. In the 1940s a dollar a month was significant, and made the difference for many people in affording a phone line or not. In the
1950s the demand for service was so high that people were forced to have party lines due to insufficient capacity.There was a Rock Hudson Doris Day comedy film "Pillow Talk" about forced sharing a party line in 1960. That was a common problem back then.
In cities party lines were more just 2 party or 4 party, and normally the ringing was only to the person called. The Bell System used bias and grounding to identify which of 2 or 4 parties to ring, the independents used frequency. In rural areas coded ringing was necessary because of so many people sharing a single line.
In some cases a tiny office would be more economical to automate than having an operator on duty 24/7 to handle occassional calls. The Bell System developed less-cost AMA systems for small offices that weren't as robost as a major city exchange.
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