Re: Telephone Tip/Ring Tester Schematic

[rw]

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

 

[Harry Conover]

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]

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]

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.

 

[Ross Herbert]

..

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

 

[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.

 

[Watson A.Name - 'Watt Sun']

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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