Home Telephone help needed

Status
Not open for further replies.

lundymei

New Member
Does any know any device that is able to disable other telephone lines when one is picked up or operating?

In my house there are three telephones connected at the same line with a splitter, what i like to know is that is there any device that able to disable the rest of the telephone when on is in use. I hate to chase my spying little brother when I was on the phone.

Thanks you.
 
Why not buying a standard telephone exchange like this one **broken link removed**

or a cordless phone where you can add up to 5 units like this one **broken link removed**

If it exists you don't have to make it
 
wow, lots of impractical suggestions.

look at akg's links. also check out the links here: http://www.discovercircuits.com/T/telephone.htm tons of circuits to draw from. this is failrly simple thing to do.

note, the FCC has nothing to do with licensing wired telephone devices. In other countries, you may run afoul of the local PTT but in the USA , it's not an issue.
 
philba said:
note, the FCC has nothing to do with licensing wired telephone devices. In other countries, you may run afoul of the local PTT but in the USA , it's not an issue.
Click to expand...
Oops, I was wrong. Sorry about that. I just thought I remember reading somewhere that hooking up homemade devices on telephone lines is on the verge of illegal.
 
the issue that i am aware of is the load on the telco line - I think they let you have 2 or 3 ringer equivalents. a bit of research should turn up the actual current draw but I *think* its 70-80 mA.
 
He wants to disable the phones that are not in use. The link you provided goes to line in use indicators. Now I am interested in how this would be done
EDIT: The links that akg posted would not apply either. He doesn't want to converse privately with someone in his house (where the phones are hooked in parallel). He wants to keep his little brother from listening in on his dirty talk with his girlfriend.
 
Last edited:
Hi,

Mobile Phones (Cell-phones) are very cheap here in England.
Newer ones with cameras in them, and internet access are expensive,
but older ones which are just telephones are very cheap.
They are also pretty cheap to use, and texting is cheaper still.

I suggest you get a cheap one.

Over here in England we also have to get a little insert called a SIM card,
they can be bought for about four quid (pounds sterling) if you shop
around.

Most technical goods seem to be cheaper in America than they cost
here, so you may well get one even cheaper.

John
 
When a phone line is in use, the voltage across the lines drops to around 10V, and it's around 50V when all phones are on-hook. Perhaps a circuit that uses a zener diode and a N/O relay to allow lock other phones out. I'm still thinking on how you'd keep it from disconnecting you.
 

think about it. if you can indicate that a phone is on the line, you can certainly disable another phone. use the indicator circuit with an opto isolator, NPN transistor, couple of resistors and small relay. you can probably eliminate the opto but it's good insurance.
 
philba said:
note, the FCC has nothing to do with licensing wired telephone devices. In other countries, you may run afoul of the local PTT but in the USA , it's not an issue.
Click to expand...

The "PSTN" (Public Switched Telephone Network) is convered under FCC's part 68 regulations. There are a (small) pile of rules that should be followed, and anything connected up is supposed to be certified (i.e. CYA in case someone submits a complaint).

**broken link removed**
**broken link removed** [section 7]

Then again officially by the FCC's standards, once you build 10 copies of any circuit, or put any of them up for sale, you're supposed to submit a sample to a certifications lab for emi/emissions testing.

In any case, there are some technical guidelines that you can use to guide the design.

James
 
I think I see what you are saying, but that would mean that only one phone would be private(the one without the indicator and disabling circuit). Let me see if I am getting what you are saying.

1. As I understand it, the indicator circuit goes at each telephone. Whenever someone is using any telephone, all of the indicator leds will light up.
2. You want to use the output (led) to activate a relay to disconnect that particular phone.

If this is correct, then privacy could only be had from one phone. And indeed only one phone could ever be used. When you pick up a phone with the privacy equipment on it then you are disconnected by the relay. Then there is the matter of hiding the unit at each telephone location (little brother will certainly figure to bypass the new fangled device) Perhaps I am missing something. Please correct me if I am wrong.
 
Phone isolators

These are available in New Zealand or were a while ago through Dick Smiths www.dse.co.nz. product number F9972 However I think you would need one on each phone as from what I remember it cuts the other phones out from the one you are using
 

Good answer. That's what the OP is really asking for.

I have search the NET and came up with the following link. I don't know whether it is legal for the OP to use the design in his country so it is offered as a reference only.

**broken link removed**
 
Status
Not open for further replies.

Similar threads

S
  • Question
Help needed for 24V Charging w/ Variable Speed Gen
Replies
10
Views
2K
Roff
  • Question
Tiny display needed
2
Replies
22
Views
3K
MaxHeadRoom78
R
  • Question
Any potential problems with my diy home battery?
Replies
6
Views
3K
Diver300
D
D
  • Question
LED light help needed (booster? converter? relay?)
2
Replies
27
Views
6K
Les Jones
L
W
  • Question
Building a quantized sequencer without programming (MC)
2
Replies
27
Views
3K
rjenkinsgb
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…