Re: Phoneline Diverter

From: hepcatbrandon (jberryman_at_primposta.com)
Date: 10/31/04 

Date: 31 Oct 2004 07:40:19 -0800

jberryman@primposta.com (hepcatbrandon) wrote in message news:<c2b5e1c.0410301238.4782bea6@posting.google.com>...
> Hi everyone. I've just begun to learn about electronics and wanted to
> try my hands at making a diverter (or rather a variation on a design
> that I found), and I could use some help. The purpose of this circuit
> is to connect two phone lines together so that when you call LINE 1
> you get the dial tone of LINE 2 and can send DTMF and talk just as if
> you had dialed out of LINE 2 directly. I appologize in advance for my
> ***-ugly illustrations (see links) and general newbiness; the
> drawings are meant to just show the basic logic, as that's enough for
> me to worry about at the moment.
>
> This is the first sketch I came up with:
>
> [img]http://jupiter.walagata.com/w/jberryman/gold_box_illustration_copy.jpg[/img]
>
> To explain: In the position shown, both lines 1 and 2 are "on hook". I
> dial up the number for LINE 1, the CO sends AC (ringing) current to
> line 1 and the capacitor allows current to flow into the full wave
> bridge rectifier, sending DC through the relay.
> This closes both circuits in LINES 1 and 2, LINE 1 stops "ringing" and
> allows DC to flow through LINE 1 and through LINE 2. Now it is LINE 2
> that is keeping the relay open. Both lines are now "off hook".
> The gold blotch represents the undefined connection between the two
> lines that is the purpose of the circuit. I have been trying to find
> information about DC coupling but it all seems very complicated. The
> design that I initially found used a 600ohm-600ohm transformer, but is
> there an easier way? what would happen if you connected them with a
> bit of wire?
> Now when the call is completed and whoever LINE 2 calls hangs up, the
> CO will initiate a polarity reversal on LINE 2 that will cause the
> circuit to collapse and reset. There is a problem if LINE 2 dials
> something that never hangs up, however...
>
> Which leads me to v0.2:
>
> [img]http://jupiter.walagata.com/w/jberryman/gold_box_2_copy.jpg[/img]
>
> Now this may be crazy, I don't know. But in this design, when the
> relay is thrown, LINES 1 and 2 are connected in a figure eight or
> infinity symbol shape, with RING of LINE 1 flowing into TIP of LINE 2
> and vice versa. This way, a polarity reversal on either end will reset
> the circuit and I don't have to learn about coupling.
>
> Does either design make sense? If not why? Any advice you can give me,
> even to tell me what to go about reading into would be great.
> Thanks

Thanks a bunch, Andrew, for the input. This project is just for fun...
there are easier ways to make free calls.

Don, the polarity reversal is the disconnect signal at least here in
the US. You know how when you stay on the line for a few seconds after
someone has hung up, you hear a click then another click then dial
tone? If you could take a minute to tell me what doesn't make sense
about the drawing, I'd appreciate it.

Graham, find me a PBX that can fit in the palm of your hand and costs
five bucks and I'll glad to dish out the money. And sucks to BT.