A Phony Question

[SparkyCal]

I have a quick question. I have made the circuit shown on this webpage: https://www.circuits-diy.com/telephone-in-use-indicator/#Circuit_Explanation

Basically, the purpose of the circuit is to light an LED when a phone is in use. The explanation says "Furthermore, the external power source is not required as the circuit draws power from the line."

On the schematic, on the left, you will see two entry points labelled Input from Line. I am assuming that these get connected to the telephone line coming into the phone jack.

More specifically, my question is, should these two entry points be connected to the red and green wires of the phone line?. If so, is there a particular order (should the red go to the connection shown toward the top and the green go to the connection below that), or does it matter?

Thank-you

 

[Martaine2005]

Strange colours for a phone line.
Usually blue, blue/white- orange, orange/white etc.
And blue, blue/white being the line.
But as it’s AC, connect yours either way.

 

[be80be]

Can be 90VDC
The 48 VDC is current limited by series resistors (one in each leg), therefore phones “on-hook” (no current drawn) typically measure 48 VDC, while phones “off-hook” (current drawn) typically measure 6 – 8 VDC.
Ac is used to ring the phone.
Red and green are old type wiring red was hot and green was ground

 

[davenn]

Strange colours for a phone line.
Usually blue, blue/white- orange, orange/white etc.

depends on where ya from
in Australia it's also red and green

 

[be80be]

Here they just started using cat 5 blue blue white line 1 and green green white but years ago it was red green

 

[Martaine2005]

Here they just started using cat 5 blue blue white line 1 and green green white but years ago it was red green

Where’s here?
I’m in the UK
EDIT: Sparkycal is in Canada!

 

[AnalogKid]

Unofficial data from the 60's-70's:

In the US, the standard cable from the pole and running around a house is 4-conductor, with only t conductors used for normal residential service. The inside stuff is called J-K (reason unknown) with a grey or olive-grey outer jacket (although I have a spool of white from somewhere). The primary pair is red and green, with the red wire being more negative. The secondary pair is yellow-black, used for a second line or for 6 Vac to light the dial of a Princess phone.

The colors in post #2 usually are for multi-pair cables such as 6-pair or 25-pair. My house was built by a commercial contractor, and unjacketed 6-pair is everywhere, even though the underground cable out to the pole is standard 2-pair. From the suppressors in the basement there are two independent runs. One daisy-chains the basement and first floor jacks, including what was the builder's home office, and one goes to the second floor rooms.

Fun fact - when we redid the kitchen, we found buried inside a wall ***135 feet*** of the second floor 6-pair cable zig-zagged between two nails about 3 feet apart. As service loops go it is a personal record, with absolutely no way to access it. Never seen anything like it since. Even in the heavily structured and regulated world of 1970's Bell, there was a little personal creativity here and there.

ak

 

[AnalogKid]

should these two entry points be connected to the red and green wires of the phone line?.

Yes.

is there a particular order (should the red go to the connection shown toward the top and the green go to the connection below that), or does it matter?

Does not matter.

Diodes D1-D4 form a bridge that adapts either line connection polarity to the polarity of the circuit. This is common in many phone line circuits. If you have an extension phone, answering machine, or whatever, that is sensitive to the phone line polarity, it is an indication that they cheaped-out on the design and eliminated 3 or even all 4 of the diodes.

ak

 

[SparkyCal]

Thanks for your help. I think coloring schemes vary between countries and between residential vs commercial uses. That’s my understanding,anyway. And yes, I am in Canada. Thanks again my friends.

 

[Externet]

Telephone in-use indicator ? Did that 40 years ago for an office that had only one telco line. Everyone looked by the ceiling where the LED was before lifting the handset

L1--------------------20Vzener--------------greenLED-----------/\/\/\/----------------L2

Simply in parallel to telco: voltage in the telco line needs to be over the zener to turn LED on at around 5mA or less ~15Kohm. LED off means line is busy. Busy line is under ~16 V. Otherwise, around ~48V shows LED-on as line available. Observe polarity. Wires color does not matter.

 

[AnalogKid]

And the telco didn't try to find out why there was an almost 24/7, 5 mA fault current on a line?

ak

 

[Martaine2005]

All these pesky dial tone LEDs

 

[Externet]

And the telco didn't try to find out why there was an almost 24/7, 5 mA fault current on a line?

Never Thinghy worked flawless for years. Perhaps there is a limit to the 'leak' current, or, If current is not enough to seize the line; nobody cares if there is a 'leak' current.

 

[Externet]

This thread triggered nostalgic times and revisited my telephony parts bins. Among the gadgets, a transistor radio I made to work from the telco line power for no-AC mains emergency situations, crimpers, connectors, global adapters, polarity indicator probe, fax machines interconnect, xenon and neon ring flashers, ring generators, more not in picture... mostly late eighties. Those were great times.

 

[Delta Prime]

The inside stuff is called J-K (reason unknown)

I asked my great grandpa who has a whimsical perspective and worked for a company he calls Ma-bell, he said unofficially he called it “Mary Christmas Cable”.
Red & Green looked like the letter
”J” & Yellow along with Black looked like the letter “K” Because when he was looking at the wire bundle; "J" representing the twisted pair of red and green, and "K" representing the duo twisted pair of black and yellow, when you unravel the cable bundle & terminate to the phone box, where you plug your phone into.