# Telephone privacy device

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#### PinksteR

##### New Member
Hi, im tring to do a device that blocks the other phones in the line
when a phone is active, the proyect im using is this:
https://www.epanorama.net/circuits/tele_privacy.html
but i couldnt find the triac used in the main proyect, so i got the parts of the "Modifications Ideas" part. But the triac pinout is different and i dont know how to do the connection.
im trying to do what is said here:
https://groups.google.com/groups?hl=es&lr=&ie=UTF-8&selm=6n3alq$pg7$1@news.kolumbus.fi
The problem is with the connections. I know that i have to solder the
gate of the triac to the diac, but then i dont know how to connect the
phone line to MT1 and MT2, and where to connect the other side of the
diac.
Also i dont know if it's the same to connect them in any of the 2
lines of the phone line.
I would apreciate a lot if u can help me.
Thx

#### Sebi

##### Active Member
You can connect it serial to any wire of tel.line. Triac pinout see in projects forum.

#### daviddoria

##### New Member
hmm i am very confused as to how that circuit works... how does it stop the other phones from being able to be used without cutting off the call completely??

#### PinksteR

##### New Member
Sebi, so i connect MT1 and MT2 to phone line (any wire) and then i connect gate of triac to diac, but the other side of the diac goes to MT1 or MT2?? This is my main problem..

daviddoria, in the proyect url i posted everything is explained very well.

Thx u guys for helping

#### Sebi

##### Active Member
The diac between the gate and MT2.

David,

it works fine, because on-hook position no current-flow (hookswitch off),and line voltage about 50V.
If the hookswitch on, the DIAC fired the TRIAC, current can flow, and the line voltage decreased about 10V. (DIAC can conduct, when the voltage of pins about 30V) The parallel phone also contain same circuit, and these circuit can't work with 10V.(My experience: if i switch off only one wire of phone, in full silent i can hear some conversation in parallel device.)

#### PinksteR

##### New Member
thanks a lot Sebi, i think now im ready to build those devices....
Last question, MT1 and MT2 need to be connected in a specific way? like MT1 should be connected to line wire and MT2 to phone wire or any way will work?

#### Sebi

##### Active Member
TRIAC is a bidirectional device, in this case no marked in or out.

#### bogdanfirst

##### New Member
ok, thinking of a privacy indicator, i think it would be nice to have an indication with a led when you have the phone in use....
and i have question, let's say i have more phones and each has a circuit for protection....and i want to moove from one phone to another, is it possible?

#### Sebi

##### Active Member
Hey Bogdan, this is a practical question... First made on-hook the phone1,move to phone2, off-hook it. In Hungary the tel.company not break the line about 10sec if i was ringed.

#### PinksteR

##### New Member
it works!

Thx a lot guys!! i could make it work. i installed 12 devices all around my home
bogdan idea is pretty intresting.. a LED that indicates if the phone is being used or not. Anyone knows how to do this?
Thx

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