Telephone Privacy Adapter
Donny Mah
Hi,
I'm wondering if anybody has plans for a privacy adapter so that if
multiple phones are
connected in parallel, only one can be used at a time, but all will
ring.
I know of commercial designs and components to do them, but I can't seem
to source
the component (HS-20 made by Teccor, currently discontiunued from what I
understand) and the design should work bidirectionally (non-polar
design).
If anybody out there knows of a simple and cheap design, or knows where
I can obtain
the part, please e-mail me.
Thanks.
Paul & Fiona Bellett
Donny Mah <wf...@freenet.victoria.bc.ca> wrote in article
<3554F845...@freenet.victoria.bc.ca>...
One can be obtained from Dataparts Ltd, New Zealand.I use one, so other
members of the Household, don't cut me off the internet. :-), when they
pick up another phone.
You are looking at about $10 US for one.
Cheers Paul.
Bob Gudgel
Yes, What you do is put a DIAC in series with each phone. This device
which is a 2 leaded kind of thyristor, will start to conduct when it's
trigger voltage is reached, (I use a 20 Volt one), which would
be the case when all phones are on hook. When a phone is picked up, the
DIAC that was turned on will continue to conduct and the others will
not have the 20 volts or so to start conducting when it's phone is picked
up. The other person that responded to this question was right in
that you can pick these things up for about $10 at (I think) hardware
stores and such.
Bob
Donny Mah (wf...@freenet.victoria.bc.ca) wrote:
: Hi,
: I'm wondering if anybody has plans for a privacy adapter so that if
: multiple phones are
: connected in parallel, only one can be used at a time, but all will
: ring.
--
K7IQ
JimWall
Donny Mah wrote:
>
> Hi,
>
> I'm wondering if anybody has plans for a privacy adapter so that if
> multiple phones are
> connected in parallel, only one can be used at a time, but all will
> ring.
>
> to source
> the component (HS-20 made by Teccor, currently discontiunued from what I
> understand) and the design should work bidirectionally (non-polar
> design).
>
> If anybody out there knows of a simple and cheap design, or knows where
> I can obtain
> the part, please e-mail me.
>
> Thanks.
diodes (12V to 16V would be fine). Connect the zeners back to back in
series with either tip or ring (insert the diodes in series with one
side of the phone line, either anode to anode or cathode to cathode).
What this does is require that the telco line voltage exceed the 5-9
volt offhook voltage *plus* the zener voltage for the phone to work.
Once another phone is off hook the line voltage drops below 10 volts
and now the protected phones cannot join the call.
Zener diode cost is $.20 or so.
-Jim
John Lundgren
JimWall wrote:
> Donny Mah wrote:
> > Hi,
[snip]
> > Thanks.
> There are several designs possible. The cheapest one is to use two zener
> diodes (12V to 16V would be fine). Connect the zeners back to back in
> series with either tip or ring (insert the diodes in series with one
> side of the phone line, either anode to anode or cathode to cathode).
> What this does is require that the telco line voltage exceed the 5-9
> volt offhook voltage *plus* the zener voltage for the phone to work.
> Once another phone is off hook the line voltage drops below 10 volts
> and now the protected phones cannot join the call.
> Zener diode cost is $.20 or so.
> -Jim
A zener may work just fine for a single instrument like a fax or
answering machine and nothing else. But he wanted it for multiple
phones on the same line.
This won't work if all the phones on the line have zener diodes. The
first phone to pick up will leave phone plus zener voltage across the
line, which just means that the next phone that's picked up will have,
you guessed it, phone plus zener voltage, and it will conduct also.
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CyberCir
The current "circuit du Jour" displayed on our web site is just what your
looking for. Also you may want to download the free circuit reference
software.
Damian Bonicatto
PTM
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Mika Koistinen
Howdy
There is an article in Elektor Electronics Dec/93, that you may find
interesting.
All you need is one triac and one diac per telephone.
In each phone to be protected,a triac is inserted in series with the A line.
A diac is connected between the anode and the gate of the triac.
This circuit was desinged by L.Lemmens.
Triac TIC206D
Diac BR100
Donny Mah wrote in message <3554F845...@freenet.victoria.bc.ca>...