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get power from phone line

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alitex

New Member
i use sm8223 as CID detector i want power from phone line to run it,
i need 4V , 20 mA, is there circuit for that,


thanks alot
 

Boncuk

New Member
It's illegal to use telephone power for any other application than the telephone.

Telephone lines also carry internet data and a false terminating resistance will be detected and located at the telephone company.

Fines are considerably high for misuse of telephone lines.

Boncuk
 

Externet

Active Member
Alitex: answered in another forum.

Boncuk: What is "false terminating resistance" :confused:
 

giftiger_wunsch

New Member
I believe by 'false' he means that it's unexpected resistance for a telephone.

Makes you wonder what happens if the phone socket has a short in it? You get fined anyway?
 

mvs sarma

Well-Known Member
I believe by 'false' he means that it's unexpected resistance for a telephone.

Makes you wonder what happens if the phone socket has a short in it? You get fined anyway?
a faulty situation is different from user manipulation. telcos wont generally bother, but when it lands into complaints like ring tripping but call not thro', they check
the customer looses the call, and the Telco looses its bucks as more a call is spoken more the revenue it fetches, at least on long distance calls
 

tcmtech

Banned
Most Helpful Member
Accidental Vs deliberate is different.
If you cant afford a battery you cant afford the phone connection or the resulting fine if caught using the lines for a power source.

Use a rechargeable battery and a solar panel. The size needed for your application would be rather small. And likely cost about the same as what a building a very small and efficient switching power supply would cost any way .
 

giftiger_wunsch

New Member
My parents bought a solar-powered lamp (irony alert) the other day for £5: came with three (low-capacity) NiMH AA batteries, and a 4-inch square solar panel to charge them. Not sure what the rating of the panel is, I have a feeling I'd be attacked with it if I took it apart to check :D
 

alitex

New Member
It's illegal to use telephone power for any other application than the telephone.

Telephone lines also carry internet data and a false terminating resistance will be detected and located at the telephone company.

Fines are considerably high for misuse of telephone lines.

Boncuk

Alitex: answered in another forum.

Boncuk: What is "false terminating resistance" :confused:

I believe by 'false' he means that it's unexpected resistance for a telephone.

Makes you wonder what happens if the phone socket has a short in it? You get fined anyway?

Accidental Vs deliberate is different.
If you cant afford a battery you cant afford the phone connection or the resulting fine if caught using the lines for a power source.

Use a rechargeable battery and a solar panel. The size needed for your application would be rather small. And likely cost about the same as what a building a very small and efficient switching power supply would cost any way .
My parents bought a solar-powered lamp (irony alert) the other day for £5: came with three (low-capacity) NiMH AA batteries, and a 4-inch square solar panel to charge them. Not sure what the rating of the panel is, I have a feeling I'd be attacked with it if I took it apart to check :D
ok, i'll ask one question
you don't have telphone device that has CID detector and work with out battery(just it connect to telco line)?
how it work ????:(
 

Mr RB

Well-Known Member
A CID is an LCD device (very low power) and telco approved (it'll have a telco sticker)
You mean the sticker that Chinese companies will put on your product no matter what it does, how it works or if it has ever been tested?? ;)
 

mvs sarma

Well-Known Member
Hello mvs sarma. What does this mean ?
when we try to take small currents from telephone line, the exchange would rather neglect till it touches the limit set for leakage.

What I meant was, suppose you tey to take 1mA from the phone line, there is a possibility that, on an incoming call ring might trip, thus it is likely that you may miss Incoming calls.
there are of couse devices that make use of this small currents and convert to useful voltages of say 5V 5 mA etc to run devices like CID.

In this case of CID mentioned by OP, if the CID has teleco line input and output sockets , he could well try it out.
 

Externet

Active Member
Hi.
If 1 mA; or 5 mA or more are taken from the on-hook telephone line, nothing will happen if the dial tone is not present and the incoming call will ring with no problem.
Only when the current taken from the telephone line exceeds the treshold to engage the central office relays, usually around 18 mA, then the dial tone and the busy tone are enabled and the ringen disabled by the relay contacts, preventing an incoming call from passing trough.

Modern central offices may not use true relays in their linecards, but the functionality persists the same, and some automated test may flag a current being taken as a failure, a leak, or an intentional load.

Miguel
 

mvs sarma

Well-Known Member
Hi.
If 1 mA; or 5 mA or more are taken from the on-hook telephone line, nothing will happen if the dial tone is not present and the incoming call will ring with no problem.
Only when the current taken from the telephone line exceeds the treshold to engage the central office relays, usually around 18 mA, then the dial tone and the busy tone are enabled and the ringen disabled by the relay contacts, preventing an incoming call from passing trough.

Modern central offices may not use true relays in their linecards, but the functionality persists the same, and some automated test may flag a current being taken as a failure, a leak, or an intentional load.

Miguel
The limit varies with the equipment manufacturer and it is meant as guard for leakage across the limbs, due to low insulation. for example e10B and their latest designs from Alcatel it around 4 mA.
Relays are still used, though not for line feed sensing. the are across line card and meant for say, Ring feed, line test, Limb reversal after called party answer, in case on Coin box phones.
Nice to discuss these aspects
 
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