Power Supply using phoneline

seadolphine2000 · Nov 18, 2005

I've measured the AC output of my phoneline socket and found the following:

118 Volts AC when no incoming calls.
152 Volts AC when the phone rings.

I'm thinking about using a 220 - 12 transformer to stepdown this AC voltage in order to use it as a power supply.

Is this possible.?
What are the constrasins.?
Any ideas.??

Thanks very much to all of you.

IanP · Nov 18, 2005

Telephone Power?
From: henry@zoo.toronto.edu (Henry Spencer)

" If one were to try [using power from phone line], would phone company had a way of finding out?"

Most assuredly. They aren't in the business of supplying power, and they ARE in the business of finding faults in their lines. Any substantial power drain from their lines WILL be detected. If it's large, the phone switch will conclude that you've dropped the phone in the bathtub or something like that, and will disconnect your line (and will check periodically to see if the drain has gone away and you can be reconnected). If it's small, the switch will report it to the service people as a possible line problem, to be investigated before it causes a complete failure... and if they investigate and find that you're to blame, they will probably send you a bill for time and trouble. The current you can draw without eventually having it noticed is very small.

Quoted from:
**broken link removed**
(a lot of telephone-related circuits)

If you are going to draw very small currents (<5mA) you can supply small circuits (examples in the above link) directly from the line ..

Regards,
IanP

mesfet · Nov 18, 2005

Hi seadolphine2000,

Do you mind telling where are you living? 118V is high voltage. Also, the voltage of phone line in my country is DC. In order to step it down, you need to convert it to AC first and then.......etc. Not sure how much power you can extract from the phone line. I guess one concern is that the applicance you are going to power may load the phone line too much.

Mesfet+

seadolphine2000 · Nov 18, 2005

Thanks to all of you, I'm from Egypt.
I measured the output from the phone using a multimeter and found the above readings.

I made the phone line indicator circuit and it used a bridge rectifier, that's why I thought that I could use the DC output as a power supply.

I tried to place the 220-12 transformer but it makes problems with phone line itself.

Can I use it to supply electronic circuits.??

shafee001 · Nov 18, 2005

no way it's 0 A supplay? that means when you connect a lodat vlot becoms 0 volt,
voltage when phone hang on 50v DC, and when hang up is 10 volt DC

Power Supply using phoneline

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Power Supply using phoneline

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