How is the ring of a telephone powered ?

[saowaluck]

The ringing of telephone

I would like to know about the ringing of telephone.It is use power from.... Where? DC or AC and voltage value?I would like to get the document or website or your suggest. Thank you

 

[Rayengine]

Re: The ringing of telephone

Corded phone is from power of telephone company (48Vdc + AC Ring Voltage - as high as 100Vrms).

 

[papyaki]

Re: The ringing of telephone

Hi,

In Europe, phone line terminal requirements are describred in TBR21.

You can download it in this old post (scroll down) :

 

[delay]

Re: The ringing of telephone

It is -48VDC superimposed with a ringing cadence of 20 Hz giving a Vrms 90 to 120V that can give a good jolt.

 

[eemapir]

Re: The ringing of telephone

hi
it is uses the voltage of dc of the line
bye

 

[penrico]

Re: The ringing of telephone

hi
it is uses the voltage of dc of the line
bye

Noooo, it not use DC at ringing moment.

When there is a ringing, the phone central puts depending of country from 20hz to 65Hz, 30 to 120 Vrms over the line. The phone terminal is powered using this high voltage in AC to drive the ringing speaker ringer. In most phones the ringing signal is passed through a DC decoupling capacitor about 0.47 uF and a total resistence of circuit about 10Kohm, the ringing current is about up 2mArms, or less.

When you make the call, (pick up the phone), the phone central puts the line tension (about 24/36/48 or 72 Volts), and cause the line impedance and line resistence, the total voltage in phone is about 6 to 10v, it makes a current about 20 to 40 mA, the phone uses it current to be powered, during a phone communication. Audio signal is current modulated over the DC tension (audio is about 0 dbm max 700 mVrms)

 

[kingsr]

Re: The ringing of telephone

The phone power is 48V(DC) ,Ringing is 120v AC(RMS).

 

[ykishore]

Re: The ringing of telephone

view the site for visualisation of the working of telephone

**broken link removed**

 

[ykishore]

Re: The ringing of telephone

Why to use DC coupling capacitor?

 

[penrico]

Re: The ringing of telephone

Why to use DC coupling capacitor?

Cause the ringing signal is an AC signal, so only way to detect it is let pass only AC signals, this is done using an capacitor, DC line power is always on during ringing too.

 

[Borber]

Re: The ringing of telephone

Ringing circuit in telephone is allways connected to line unless you pick up speaker and close DC circuit what indicates that telephone is active. So capacitor is needed to disconnect DC closure while telephone is waiting for call.

 

[papyaki]

Re: The ringing of telephone

Hi,

Look at this application note from Midcom. A full line interface with schematics with component list :

h**p://www.midcom-inc.com/tech/tn88.htm

* = t

 

[DoctorX]

Re: The ringing of telephone

Ever since I switched to Verizon phone company, whenever I dial somewhere, such as Audix answering system, and hang up in the middle, the telephone will ring, I have to pick it up, slam it, for quite a few time before it will go silent.

I called Verizon's customer support, she made me believe that it is a "feature" to prevent you losing unfinished phone calls, then she admits that she gets this at home, too.

 

[ssm1969]

Re: The ringing of telephone

Ringing circuit is 70+-10Vrms AC. Anybody know about circuit? Manufactures?

 

[FD357]

The ringing of telephone

I saw a book "understanding telephone electronics"