David Nyarko <nyarko@ee.ualberta.ca> (04/26/91)
I dismantelled an answering machine stopper centered around a phone
jack splitter having red and green status indicator LEDS . See
article #4 in SUMMARY below. This was a MELTONE device.
A figure of the setup (a MELTONE device) is indicated below.
GREEN LED
IN + |--|>|--| B311 B311 OUT1 +
--------*-* *----((...)--(...))----
| |--|<|--|
| RED LED
IN - | OUT1 -
-----*--|------------------------------
| |
| *------------------------------ OUT2 +
|
*--------------------------------- OUT2 -
Legend:
1) IN +, IN - : connected to wall socket.
2) OUT1 +, OUT1 - : connected to device you want to disconnected when
an extension phone is picked up. (In this case the answering machine
will be connected here.)
3) OUT2 +, OUT2 - : connected to telephone or 2nd device.
For B311 devices,(Possibly 11volt zeners)
(( = black marking on device. (Cathode band)
For LEDS
Anode ----|>|--- Cathode
4) * : 2 or more wires connected together.
Comments:
a) Green LED turns on when answering machine accepts call and turns
off when machine goes off or any extension telephone is picked up.
b) Red LED never turns on. From the circuit, It could turn on if the
IN +, IN - are reversed.
c) Actually 2nd B311 device near OUT1 + might not be required if the
IN + and IN - polarities are not reversed.
COMMENTS ARE WELCOME: Email to nyarko@bode.ee.ualberta.ca
Please find below the summary of the responses received so far. Item
# 2 appears to be incomplete so I have asked if he could please
re-mail his response.
I have not tried out any of the recommendations. # 1 seems the 1st type
I would try.
----------
1)
Date: Mon, 22 Apr 91 09:15:05 CDT
From: ho@csrd.uiuc.edu (Samuel W. Ho)
Many answering machines now have this capability built in. The way it
works is to raise the answering machine's threshold for line voltage
detection. The easiest way is to put in a Zener diode of about 12-15V
in series with the answering machine phone line connection. If
another phone is off hook, the current draw pulls the line voltage low
enough that no signal gets to the answering machine through the Zener.
The answering machines that do this automatically work by having three
voltage ranges detected: 50-90VAC is ring, 12-50V is normal line
voltage, below 12V is disconnect. Incidentally, CPC is picked up by
the same circuit. (Voltage thresholds vary, depending on how far you
are from the central office.)
Sam Ho
----------
2)
Date: 22 Apr 91 06:27:29 PDT (Mon)
From: pevans@cynic.cynic.wimsey.bc.ca (Phillip Evans)
advertised as doing exactly what you said you need to do. Mine works
fine - it cost about $10.
----------
3)
Date: Mon, 22 Apr 91 12:43:34 -0400
From: irvin@northstar.Dartmouth.EDU
I have such a device, called PHONE ALONE. When any extension in the
house is picked up, it disconnects whatever device is connected to it
(in my case an answering machine), but it is advertised to be used
with a phone extension (for privacy). When the extension is hung-up
it resets to normal operation.
I believe I got this sucker from The $harper Image. If you can't find
it let me know and I'll try to find out where it can be had.
Tim Irvin
----------
4)
Date: Mon, 22 Apr 91 14:13 CDT
From: rvt@sbctri.sbc.com (Roger V. Thompson 7847)
Organization: Southwestern Bell Technology Resources, St.Louis, MO
I saw a device that seems to do what you want at Walmart last
Saturday. It was about the size of a two-way modular jack splitter and
had a couple of led's to indicate which side was active. I didn't
check the price.
Roger
----------
5)
Date: Mon, 22 Apr 91 14:02 CST
From: Mike Gordon <99681084%ucs.UWPLATT.EDU@vm.ucs.UAlberta.CA>
Organization: University of Wisconsin--Platteville
Radio Shack has a little donger that does that. It's called the
teleprotector and it runs $7.95. (item number 43-107)
I built a little bugger that did the same thing and it ran me about
$10. (and soldering iron burns on my fingertips :( )
Mike Gordon 99681084@uwplatt.edu University of Wisconsin - Platteville
----------
6)
Date: Tue, 23 Apr 1991 19:27:00 -0400
From: "Joel C. Justen" <JCJUST01@ULKYVX.BITNET>
I found one of these at 'Target' which is a large discount store chain
here in the US. It's basically just a plug which plugs into the jack,
and has two separate plug ports with leds on them for the phone and
the answering machine. It detects whether or not the phone has the
line or the answering machine, and if it is the phone, it disconnects
the answering machine portion. I think you can also find this at
Radio Shack if you can find one.
Cost? 2.95.
---------
7)
Date: Wed, 24 Apr 1991 23:19:00 -0600
From: Toby Nixon <decwrl!uunet.UU.NET!hayes!tnixon>
Well, I can't point you at a "circuit" (you want to build it
yourself?) but I can tell you that they sell these at lots of places
around Atlanta for about $5.00. I have on on my answering machine at
home. Generically, they are known as "answering machine stoppers".
---------
8)
Date: Wed, 24 Apr 1991 10:19:00 -0600
From: hugh.graham@rose.toronto.edu
David,
Radio Shack has a FAX/TAD controller as you describe in the
Canadian catalogue on p. 88, part 43-8015. It has no CSA or DOC
approval, but since it's a passive device perhaps that's not
necessary.
Anyway, RF on the phone line sometimes prevents this gadget from
making up its mind. I have several, and have moved all of them to the
grounded lightning block in the basement so that computer and voice
are exclusive, and picking up the phone disconnects the answering
machine. In the basement they're all decisive. It's also possible
that Alberta will have less RF floating around than Metro Toronto...
Hugh