Telephone Tip/Ring Tester Schematic

[Don]

Can anyone point me to a telephone line tester circuit on the web somewhere?
I am looking for something that will indicate whether the line is alive and
whether the tip and ring signals are reversed. Tried doing a Google search,
but came up with ready, made ones. I have enough junk around here that I
figure I can build one for nothing.

Thanks!

Don

 

[rw]

Don wrote:

Can anyone point me to a telephone line tester circuit on the web somewhere?
I am looking for something that will indicate whether the line is alive and
whether the tip and ring signals are reversed. Tried doing a Google search,
but came up with ready, made ones. I have enough junk around here that I
figure I can build one for nothing.

Thanks!

Don

if you got a multimeter and a phone you can start testing.
check the voltage across the pair, should be 48VDC in US, 60VDC
in europe.
place a 600 ohm resistor, 5W across the pair and measure the current
should be 20 to 40mA (holding current)
rw

 

[the Wiz]

Look here:
http://www.ee.washington.edu/circuit_archive/circuits/F_ASCII_Schem_Tel.html

or here:
http://www.imagineeringezine.com/PDF-FILES/2phostat.pdf

or here:
http://users.pandora.be/educypedia/electronics/telephone.htm

"Don" <someone@somewhere.net> wrote:

Can anyone point me to a telephone line tester circuit on the web somewhere?
I am looking for something that will indicate whether the line is alive and
whether the tip and ring signals are reversed. Tried doing a Google search,
but came up with ready, made ones. I have enough junk around here that I
figure I can build one for nothing.

Thanks!

Don

More about me: http://thelabwiz.home.mindspring.com/
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Drivers for Pablo graphics tablet and JamCam cameras: http://home.earthlink.net/~mwbt/
johnecarter atat mindspring dotdot com. Fix the obvious to reply by email.

 

[Harry Conover]

rw <rw@netscape.net> wrote in message news:<3F104E35.2070201@netscape.net>...

Don wrote:
Can anyone point me to a telephone line tester circuit on the web somewhere?
I am looking for something that will indicate whether the line is alive and
whether the tip and ring signals are reversed. Tried doing a Google search,
but came up with ready, made ones. I have enough junk around here that I
figure I can build one for nothing.

Thanks!

Don




if you got a multimeter and a phone you can start testing.
check the voltage across the pair, should be 48VDC in US, 60VDC
in europe.
place a 600 ohm resistor, 5W across the pair and measure the current
should be 20 to 40mA (holding current)
rw

How do you distinguish between Tip and Ring?

Harry C.

 

[Harry Conover]

rw <rw@netscape.net> wrote in message news:<3F104E35.2070201@netscape.net>...

Don wrote:
Can anyone point me to a telephone line tester circuit on the web somewhere?
I am looking for something that will indicate whether the line is alive and
whether the tip and ring signals are reversed. Tried doing a Google search,
but came up with ready, made ones. I have enough junk around here that I
figure I can build one for nothing.

Thanks!

Don




if you got a multimeter and a phone you can start testing.
check the voltage across the pair, should be 48VDC in US, 60VDC
in europe.
place a 600 ohm resistor, 5W across the pair and measure the current
should be 20 to 40mA (holding current)
rw

How do you distinguish between Tip and Ring?

Harry C.

 

[Harry Conover]

rw <rw@netscape.net> wrote in message news:<3F104E35.2070201@netscape.net>...

Don wrote:
Can anyone point me to a telephone line tester circuit on the web somewhere?
I am looking for something that will indicate whether the line is alive and
whether the tip and ring signals are reversed. Tried doing a Google search,
but came up with ready, made ones. I have enough junk around here that I
figure I can build one for nothing.

Thanks!

Don




if you got a multimeter and a phone you can start testing.
check the voltage across the pair, should be 48VDC in US, 60VDC
in europe.
place a 600 ohm resistor, 5W across the pair and measure the current
should be 20 to 40mA (holding current)
rw

How do you distinguish between Tip and Ring?

Harry C.

 

[Richard Crowley]

"Harry Conover" wrote ..

How do you distinguish between Tip and Ring?

In North America...
Ring = positive = red
Tip = negative = green

 

[Watson A.Name - 'Watt Sun]

In article <1yXPa.43452$C83.3442523@newsread1.prod.itd.earthlink.net>,
someone@somewhere.net mentioned...

Can anyone point me to a telephone line tester circuit on the web somewhere?
I am looking for something that will indicate whether the line is alive and
whether the tip and ring signals are reversed. Tried doing a Google search,
but came up with ready, made ones. I have enough junk around here that I
figure I can build one for nothing.

The usual way of doing this is to use a bicolor LED that glows read
with one polarity and green when the polarity is reversed. You just
put a resistor in series to limit the current. I think the ones I
have usre 3.3k, maybe more if the voltage is high. the max current
for a phone line is 60 mA, so it would be wiuse to put 3 or 4 diodes
in series in each direction to absorb any excwess current above 20 mA
or so. But the dissipation of the resistor may be more than a half
watt. So use a couple in series or a 1 watter.

BTW, if you plug one of these into a wall jack, the polarity will be
correct, but the modular line cord flips the polarity so that it's
reversed at the phone jack. So you have to know where you're testing.

More info is on comp.dcom.telecom.tech newsgroup.

Thanks!

Don

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[Ross Herbert]

Richard Crowley wrote:

"Harry Conover" wrote ..
How do you distinguish between Tip and Ring?

In North America...
Ring = positive = red
Tip = negative = green

They must have changed it then... but somehow I doubt it. See
http://www.elecdesign.com/Articles/Index.cfm?ArticleID=1539 and
http://www.ktechonline.com/pdf/Telephone_Line_Measures_042600.pdf

Anyway, if the tech reversed the main frame jumper... the wire colors
mean nothing. You need to check the polarity with respect to earth. The
normal polarity is;

The 'A' leg (or TIP) is connected to earth at the exchange and therefore
the 'B' leg (or RING) will be -ve wrt to the 'A' leg (or TIP).

Connect a digital voltmeter between both wires of the line.
When the meter reads -52V the red lead will be connected to the 'B' leg
(or RING) and the black lead will be connected to the 'A' leg (or TIP).

Ross Herbert

 

[Richard Crowley]

"Ross Herbert" <rherber1@bigpond.net.au> wrote in message
news:lAqVa.21437$OM3.5519@news-server.bigpond.net.au...

Richard Crowley wrote:

"Harry Conover" wrote ..
How do you distinguish between Tip and Ring?

In North America...
Ring = positive = red
Tip = negative = green



They must have changed it then... but somehow I doubt it. See
http://www.elecdesign.com/Articles/Index.cfm?ArticleID=1539 and
http://www.ktechonline.com/pdf/Telephone_Line_Measures_042600.pdf

And I could provide the URLs I referenced that claim otherwise.

But I agree that it isn't very relevant anymore anyway. Seems likely
that the contractors that work on phone wiring these days don't
have the same attention to detail as the first couple generations
of telephone technicians. Hard to distinguish brown with orange
stripes from orange with brown stripes in the bottom of a dark
manhole.

And it doesn't really matter anymore anyway. All modern phone
equipment will operate properly regardless of the polarity. The stuff
that doesn't isn't properly designed or assembled. Note that it
was (is?) common to reverse polarity to indicate certain things
like call completion.

 

[Dr. Anton Squeegee]

In article <vicsgmns9sled1@corp.supernews.com>, Richard Crowley says...

<snippety>

And it doesn't really matter anymore anyway. All modern phone
equipment will operate properly regardless of the polarity. The stuff
that doesn't isn't properly designed or assembled. Note that it

Ahhh... wait a moment. I understand you're referring mainly to
"modern" phones, but I still take issue with that statement!

The older Bell System (Western Electric) phones from the 70's-
early 90's are most certainly "properly designed and assembled" (as
evidenced by their amazing service life -- my key system has been going,
more or less continuously, for 20+ years), but earlier TouchTone sets
will not dial out with reversed polarity.

In fact, it was common practice among telephone installers to flip
the polarity on the connection to sets that the owner did not want
people to be able to dial out on.

was (is?) common to reverse polarity to indicate certain things
like call completion.

I've not heard of RP being used to indicate call completion
(perhaps someone else has?), but I will say that it is common for most
central offices in the U.S. to drop the line battery altogether for
about two seconds, if a phone goes off-hook and you don't do anything
for 30 or so seconds.

The reason for this dates back to the first key telephone systems,
developed in the 40's. If a line were taken off-hook, and then
immediately put on hold, or if a caller on hold hung up and the line
went back to a dial tone state, AND the hold bridge failed to release,
it could tie up common equipment at the CO.

That battery drop I mentioned above will force the hold bridge at
the customer's end to release, thus clearing the line. Even the most
modern of electronic CO's do the battery drop thing to this day.

This has been your Bell System trivia for today. We now return to
your regularly scheduled Schickelgruber.


--
Dr. Anton Squeegee, Director, Dutch Surrealist Plumbing Institute
(Known to some as Bruce Lane, KC7GR)
kyrrin a/t bluefeathertech d-o=t c&o&m
"Quando Omni Flunkus Moritati" (Red Green)

 

[Richard Crowley]

"Dr. Anton Squeegee" wrote ...

Ahhh... wait a moment. I understand you're referring mainly to
"modern" phones, but I still take issue with that statement!

The older Bell System (Western Electric) phones from
the 70's-early 90's are most certainly "properly designed
and assembled" (as evidenced by their amazing service
life -- my key system has been going, more or less
continuously, for 20+ years), but earlier TouchTone sets
will not dial out with reversed polarity.

In fact, it was common practice among telephone installers
to flip the polarity on the connection to sets that the owner
did not want people to be able to dial out on.

But as time went on, apparently it got harder to find good help.
So it became cheaper to put a 50-cent bridge rectifier in the
dialpad circuit (which they actually did), than to pay the tech to
debug why the old phone worked and the new one didn't.

Yes, I was assuming that >99% of the readers of this thread will
not have access to polarity-sensitive, early TouchTone equipment.

 

[Dave VanHorn]

But as time went on, apparently it got harder to find good help.
So it became cheaper to put a 50-cent bridge rectifier in the
dialpad circuit (which they actually did), than to pay the tech to
debug why the old phone worked and the new one didn't.

Yes, I was assuming that >99% of the readers of this thread will
not have access to polarity-sensitive, early TouchTone equipment.

When they converted the Waikiki exchange to ESS, half the subscribers lost
the ability to dial.
Seems there were a lot of reversed reversals in the middle of the wiring,
and the installers just flipped the leads till it worked.

Even into the 80's I had no true DTMF service, though the telco charged for
it.
They put a tone to pulse converter on each line. "Beep"-Dit-Dit-Dit...

This was also a time when you couldn't dial 800 numbers from hawaii.
Most frustrating when some companies had ads with only 800 numbers on them.

 

[Richard Crowley]

"Dave VanHorn" <dvanhorn@cedar.net> wrote in message

Even into the 80's I had no true DTMF service, though
the telco charged for it.
They put a tone to pulse converter on each line.
"Beep"-Dit-Dit-Dit...

They had to pay for all those individual line tone->pulse
converters!

Same in the Redlands (CA) exchange. As late as the mid-70s the DDD (Direct
Distance Dialing) was implemented in Strowger relays. (Reputed to be the
first DDD in the General Telephone territories.)

You could dial San Bernardino (opposite side of the freeway) and wait for 5
minutes of "tick-tick-tick-tick...". Or just call the Operator and tell her
you call didn't go through. Some of us didn't even bother to try dialing
first.

 

[Watson A.Name - 'Watt Sun]

In article <I7OcnQ3PetgTsrSiXTWJig@comcast.com>, dvanhorn@cedar.net
mentioned...

But as time went on, apparently it got harder to find good help.
So it became cheaper to put a 50-cent bridge rectifier in the
dialpad circuit (which they actually did), than to pay the tech to
debug why the old phone worked and the new one didn't.

Yes, I was assuming that >99% of the readers of this thread will
not have access to polarity-sensitive, early TouchTone equipment.

When they converted the Waikiki exchange to ESS, half the subscribers lost
the ability to dial.
Seems there were a lot of reversed reversals in the middle of the wiring,
and the installers just flipped the leads till it worked.

Been there, done that, got the T-shirt. Damn installers ruined a
lotta times and I get stuck with straightening out their abortions.

Even into the 80's I had no true DTMF service, though the telco charged for
it.

I had pulse dial, and got my 300 baud Smartmodem, with DTMF. I used
the TT on it once, and the Pac Hell bastards tried to contact me and
make me pay for the service. They wanmted a buck twenty a month!!
For something that benefitted them more than the customer! Finally
the Calif PUC came to their senses and made the telcos give everyone
DTMF for free, so we could all call the 'voice jail' systems without
having to switch from pulse to tone after making each call.

They put a tone to pulse converter on each line. "Beep"-Dit-Dit-Dit...

Yeah, lotta good that does the customer. Like when your number is
998-7999.

I had a Rat Shack TRS-80 Model 100 with the modem that dialed at 20
PPS, and it worked okay, too. Twice as fast as regular pulse. I
believe it still would work today, too.

[snip]


--
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###Got a Question about ELECTRONICS? Check HERE First:###
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My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Richard Crowley]

"Charles Edmondson" wrote ...

I don't remember you! I was just across the freeway, and up the
mountain in the Crestline CO. Don't think I ever got to Redlands, but
did spend a stint or two on-loan to SB main and Loma Linda. Of course,
I didn't get there till '81...

I worked at LLU from 69 and moved to OR in 78. Back then, they still had
9-10 operators with cord sets handling incoming calls (no direct inward
dialing). And the campus system was switched in a large room full of
Strowgers and twenty-four 2v wet cells the size of refrigerators.

Heard that after I left LLU became so peeved with the Redlands CO (GTE) that
they put up a private microwave and got service from across the freeway
(Colton, PacBell).