How to use 2 old phones for house paging

[tf]

hey all;

I just had an idea to solve an issue.

Anyone know how to connect two old handsfree phones together so it
acts as a poor man's paging system in the house?

The jacks and wiring would be separate from the main phone wiring -
jacks and wiring already inplace from another time.

Is it just a matter of reversing the wiring? i.e. TX > RX and
applying dc voltage?
This is in Canada so I believe ring voltage is 48v - not sure though.

I'm thinking of just having this as "always on" Nothin fancy.
So we can call the kids without always having to yell y'know?..

Thanks;

T

[Laurence Payne]

On 5 Feb 2007 08:59:55 -0800, "tf" > wrote:

>I just had an idea to solve an issue.
>
>Anyone know how to connect two old handsfree phones together so it
>acts as a poor man's paging system in the house?
>
>The jacks and wiring would be separate from the main phone wiring -
>jacks and wiring already inplace from another time.
>
>Is it just a matter of reversing the wiring? i.e. TX > RX and
>applying dc voltage?
>This is in Canada so I believe ring voltage is 48v - not sure though.
>
>I'm thinking of just having this as "always on" Nothin fancy.
>So we can call the kids without always having to yell y'know?..

Why bother, when a DECT cordless 'phone system with up to 4 handsets
is so cheap? They have a talk between handsets function.

[JohnO]

On Feb 5, 12:15 pm, Laurence Payne <lpayne1NOSPAM@dslDOTpipexDOTcom>
wrote:
> On 5 Feb 2007 08:59:55 -0800, "tf" > wrote:
>
> >I just had an idea to solve an issue.
>
> >Anyone know how to connect two old handsfree phones together so it
> >acts as a poor man's paging system in the house?
>
> >The jacks and wiring would be separate from the main phone wiring -
> >jacks and wiring already inplace from another time.
>
> >Is it just a matter of reversing the wiring? i.e. TX > RX and
> >applying dc voltage?
> >This is in Canada so I believe ring voltage is 48v - not sure though.
>
> >I'm thinking of just having this as "always on" Nothin fancy.
> >So we can call the kids without always having to yell y'know?..
>
> Why bother, when a DECT cordless 'phone system with up to 4 handsets
> is so cheap? They have a talk between handsets function.


We have one of those, and it's perfect for calling the kid in the
basement when he's jammin on his drums or guitar. He hates it too,
which is an extra bonus.

tf...you put 12VDC in series with one of the phone lines and they'll
communicate.

-John O

[Scott Dorsey]

tf > wrote:
>hey all;
>
>I just had an idea to solve an issue.
>
>Anyone know how to connect two old handsfree phones together so it
>acts as a poor man's paging system in the house?

Wire them in series with a 12V battery, and you'll have reasonable
talk power. No signalling.

In a perfect world, you would parallel them with a current-limited 48V
source, but the series connection is faster and easier for a quick and
dirty setup.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Richard Crowley]

"tf" wrote ...
> I just had an idea to solve an issue.
>
> Anyone know how to connect two old handsfree phones together so it
> acts as a poor man's paging system in the house?
>
> The jacks and wiring would be separate from the main phone wiring -
> jacks and wiring already inplace from another time.
>
> Is it just a matter of reversing the wiring? i.e. TX > RX and
> applying dc voltage?
> This is in Canada so I believe ring voltage is 48v - not sure though.

The on-hook line voltage is 48V, and around 6-12V of-hook.
That is easy enough to rig up with a battery or a wall-wart.

OTOH, the ringing voltage is 100VAC or more, and frequently
at wierd frequencies. Pretty much the same across all of
North America (and very similar to the rest of the world.)

Not practical to try to get the bells to work unless you buy a
"ringdown" box which will ring the other phone whenever the
first one is picked up. These seem to be going for $150 and up.

> I'm thinking of just having this as "always on" Nothin fancy.
> So we can call the kids without always having to yell y'know?..

Much cheaper to get one of the cordless phone things
with multiple units and intercom calling capability.

[L David Matheny]

"tf" > wrote in message ups.com...
> hey all;
>
> I just had an idea to solve an issue.
>
> Anyone know how to connect two old handsfree phones together so it
> acts as a poor man's paging system in the house?
>
> The jacks and wiring would be separate from the main phone wiring -
> jacks and wiring already inplace from another time.
>
> Is it just a matter of reversing the wiring? i.e. TX > RX and
> applying dc voltage?
> This is in Canada so I believe ring voltage is 48v - not sure though.
>
> I'm thinking of just having this as "always on" Nothin fancy.
> So we can call the kids without always having to yell y'know?..
>
> Thanks;
>
> T
>
Tomi Engdahl has much info about telephone circuits:
http://www.tkk.fi/Misc/Electronics/circuits/teleinterface.html