2 Telephone line interface

[darkopop]

need to connect two telephone lines to one modem, so when ring on first second to bee ocupied, any sugestions would bee a great help, any schematic<p>Thanks

[Externet]

Hi.
Yes, it can be done. If I understand your request; if you really mean when 1 line is in use, disable the other, you may use 2 current relays similar to teltone M949-01.
One in each line will seize and disable the other into busy mode. <p>L1A-----------R1C-------K2---L1A->
L1B-----------R1C-------K2---L1B-><p>
L2A-----------R2C-------K1---L2A->
L2B-----------R2C-------K1---L2B-><p>L1A&B = line 1
L2A&B = line 2
R1C , R2C = Relay coils (2 per relay)
K1 , K2 = relay contacts<p>A 200 ohm resistor could be used in series to each relay contact too.
At the right end of the upper schematic, a manual switch to select which line connects to the modem:<p>>-L1A----------•NCx
>-L1B----------•NCy
Cx
Cy
>-L2A----------•NOx
>-L2B----------•NOy<p>L1 = line 1 pair AB
L2 = line 2 pair AB
4PDT switch:
NCx,y = normally closed contacts
NOx,y = normally open contacts
Cx,y = common contacts<p>Maybe the ascii will be displayed fine...crossing fingers.<p>Can be done automatic too, by using the Teltone relays to energize an additional quad pole relay instead of seizing lines, but that would be another schematic.<p>If you really, really mean to disable the other line into "busy" mode at the first ring received; capacitively fed AC optocouplers would be necessary and more elaborate circuit logic to activate disabling and selecting relays.<p>Miguel

[frhrwa]

why would you want to busy out the other line when one is busy on the modem?.. doesn't make sense to me?.. I could understand using whichever line is free at the time you need the modem... an autohunt feature to grab the next available line.. if thats the case, you could do it with current sensing ckts.. looking at your line or loop current when on hook vs. off hook and set your switching to monitor this, like an auto dpdt...

[darkopop]

Thanks for your time to replay <p>I have two tel lines, when ring on first(modem answer on first) second need to be ocupied because others should not get in the first line over second.
Picking line to out would be manual it is not a problem, BUT ARE RELAYS hold second line ocupied whole TIME OF CONVERSATIN OVER FIRST LINE or only when its ring?????

[frhrwa]

where the heck is Jagodina?..

[Sterling Martin]

I think Jagodina is just south of Sanity.

[frhrwa]

oh...

[CeaSaR]

Just did a search...<p>Jagodina, Yugoslavia<p>CeaSaR

[Sterling Martin]

Oops, guess I was wrong!

[frhrwa]

wow.. they have phones there too?... ha...