A little earth ground humor

[rshayes]

Lightning strikes are certainly a problem for the phone system, especially with the overhead lines that were first used.

Normally, the telephone lines are brought down to a terminal box located near ground level on the outside of the building. That box contains some form of transient supressor connected directly to an earth ground. The supressor may have any of several forms. Early ones used carbon blocks. Gas filled spark gaps have also been used. Newer equipment may use MOV devices. Each wire had a separate transient supressor connected to ground.

I suspect that these would not survive a direct strike, but were probably meant to limit the voltage due to a strike a moderate distance away, where the series inductance of the line would tend to add some impedance to limit the current. For normal signal levels, including the ringing signals, these devices would not conduct, and both wires would be left floating with respect to ground at the subscriber end of the circuit.

On a party line phone, this point was probably used as a connection for the yellow wire from the ringer, with the other end of the ringer circuit connected to either the red or green wires by a jumper inside the phone instrument. A private line would have the ringer jumpered to the red and green wires inside the phone and the yellow wire would be unused.

[rshayes]

Hello Al,

I finally found that table buried in section 47CFR68.3 of the Code of Federal Regulations. The impedance listed is the minimum value of impedance permitted for the ringer. It appears to be the impedance for a Ringer Equivalence Number (REN) of 5.0.

[Joseph]

Robert,
that down-to-earth humor was a useful diversion.

[Chris Smith]

Finally every one gets off their butt and adds in their two cents worth, while all can agree that a dog cant be electrocuted from a broken ground.

As to the type of systems, well We can just keep listening.

As to the ground, bonded and all, aside from the Hybrid circuit, the house phone grounds, and all the other types that do exist,... well I guess that denial is out of that question.

And thanks Philba, I don’t see you introducing any continuing discussions here, Just me so far.

Philba

sheesh, even a humor thread turns into a chest thrusting, strutting, pissing contest.

Controversy sells, even brings in the discussions. It beats pure ignorance any day.

So I guess we are back on the right track.


And as to our system it still just has one power feed [52v] which includes the ringing signal [around 70 plus] coming in, plus one negative wire, and one bonded ground.

[And a Hybrid]

It reads 52 volts positive to earth ground, the other reads Zero volts to earth ground, and there is a hybrid protection bridge there to save your life at the pole. [Plus other grounds down steam]

Even if YOUR feed voltage is a negative voltage up the main wire, its still the wrong wire and its still not a ground or a negative wire.


rshayes

Keep up the jokes, Im sure you were the one asking anyway, problem with the books and practices Im sure.

You cant fool any one with a crystal ball, and so your not getting any where with statments like yours.

Unless you were here, your opinion here means zero.

But, Keep that hot button handy, I for one enjoy a good laugh and after all,.... the name of the post was ...Well good mid west humor.

Smoke and mirrors..... bait and switch .....tisk tisk

Where was our telephone guy when we needed him?

[Lenp]

Hey Chris,

Here's a few questions that maybe would help those of us who really know nothing about telephony.

What's a Sidekick 7B?
What would be needed to create a 'Phantom' circuit
How was multi-party selective ringing done in the 50's
Where's the CID signal?
What's a ring down circuit
And do the terms KTU or CPD mean anything.
How many DTMF tones are there

All else, hands down, give him a chance and keep your butt sets on MON!
And, by the way, No fair using Google, it lies!

We're watching....

[Chris Smith]

Hey Lenp

Keep watching, that’s how you learn.

Instead of trying so hard to butt your head against the wall, get off the crock and read something worth while.

What is a Plasmon, how does it occur?

What is the maximum amperage through a 20 milliamp common led?

What amperage is used in the pulse laser called the LD 90, for how long, what is its duty cycle, voltages, repetition rate, etc.

How do you improve a led by 90% with out adding in more current or power?

What runs a combustion engine, just more hot air or heat?


We're watching....

And no fair using google, assuming its even there?

Bait and switch, its so Sushi of you.

[Robert Reed]

Hybrid
My experience with hybrids had nothing to do with grounds. It is a special bridging circuit (resistive,inductive or a combination of the two) near the front end which converts a four wire system ( talk as in mouthpeice and listen as in earpiece) to a two wire system (the phone line).

[Chris Smith]

That’s your experience.

Hybrid MOV circuits, general surge suppressor, Varistors, FETS and all sorts of Hybrid circuits, all designed to take a bolt of lightning and direct it to a bonded earth ground instead of your ear.

Our hybrid already has a path to the bonded ground, measurable, and it connects to both wires.

Hundreds of people each year die from a lightning strike which then hits your ear.

I have even had the hair stand up next to my head and phone during a bolt out of the blue.

Then there are the hybrid circuits in the phone reciever, and all sorts of other types.

[Lenp]

Chris,
Now now, that's no way to act! With your professed telephone knowledge those questions should have taken less time to answer than your rebuttal.

So it's hands up, who wants to get into my post, since 'someone else' blew it off....

Gosh, I just wonder why? Even I have those answers!

I (we) will "Keep watching, that’s how you learn."

[Chris Smith]

Sushi is just bait, you will never learn that way.

We're still watching....

You may even learn something?

[Robert Reed]

Well it was just to good to last. We all had a nice exchange of information flowing in the manner that forums were designed to be. Very enjoyable until you know who got into it.

[Chris Smith]

Learning is a four letter word, twice.

Oh well, some one has to keep you awake.

Did you learn anything about the hybrid grounding circuits yet?

There is a whole book or two on the subject.

Metal Oxide Varistors is a great place to start.

[MrAl]

Hello Al,

I finally found that table buried in section 47CFR68.3 of the Code of Federal Regulations. The impedance listed is the minimum value of impedance permitted for the ringer. It appears to be the impedance for a Ringer Equivalence Number (REN) of 5.0.

Hello rshayes,

I guess what i am after is the min and max impedance of the line
itself, so the voltage drop with say a given resistive load can be
calculated.
For example, say i want to connect a 100k resistor across the line
(not that i would really want to do this) and say the max impedance
of the line was allowed to be 10k. With an open circuit ring peak
voltage of 100 volts (no resistor connected) and 10k line resistance
the load of 100k would cause the line voltage to drop to 90.9 volts
peak. This is the kind of calculation i want to do, but what i need
to know is if the line is 10k, 1k, 20k, etc., without having to actually
measure it while the phone is ringing.

BTW, thanks for the other replies too from other members, which
helps to build my information base about the phone line in general.

[MrAl]

Al,

You posted the FCC chart while I was typing my previous.

Those are maximum loop impedances. Usually only found on LONG rural lines, unless there's a problem somewhere. Exceed max impedance and maybe the phone won't ring. More likely, there won't be enough DC loop current to detect off hook.

Cheers,

Hi again,

rshayes seems to be saying that those impedances are the min
allowable for a ringer circuit.

[MrAl]

MrAl
Just to add a little clarification here.The phone line DC is derived from large 48 volt battery banks that are floated across a 52 volt charging system, neither of which poles are earth grounded. this is terminated on your end as the "ring - tip" combination that we so often hear. The actual audio signal is looking at a balanced line of nominal 600 ohm impedance. And balanced for good reason -imangine sending an audio signal over seveal miles of unbalanced line. The noise would probably bury the signal. The AC-DC divisions are accomplished as people have previously posted here. As to your referring to the 'Green' wire, were you in question as to this being a ground connection? If so, the answer is no. The first set of telco 's twisted pair entering the building is color coded red & green, - green having no relationship to ground here as compared to standard AC power installs. Each additional set of lines coming in will have their own standard color code to indentify the individual pairs.The system is referenced to earth ground though, for safety considerations,but this connection is not carried on any of these incoming wires.

Hi Robert,

Actually i didnt think it was a ground but never set out to prove this.
I called it ground for the same reason we call the negative (or positive)
lead of a battery ground simply because it connects to a circuit ground
and it's also the lead that the scope ground connects to. This helps to
give the measured signal a sense of polarity. Would be interesting
to measure the voltage from each lead to earth ground too as i think
they have max specs for that too.
Thanks for the info anyway, and also it's nice to know that they color
code them too.