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DELETED (Inactive)
4 Posts |
 Posted - May 19 2004 : 3:15:24 PM
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I was wondering how be to make a device allowing me to switch between line 1 and 2. I would also want to be able to put each line on hold seperately. How would I do this, and how difficult would it be?
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Edited by - disco-fro on May 19 2004 3:23:05 PM
Edited by - disco-fro on May 20 2004 4:55:49 PM |
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bilgin65
Apprentice
Turkey
83 Posts |
Posted - May 20 2004 : 3:14:57 PM
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you can use 2x1 mux. If you don't know something about mux i can tell you. You can control more than 2 lines by a mux. For example 4-8 lines you can control, with just 3 control pin..
bilgin65 |
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n/a
DELETED (Inactive)
4 Posts |
Posted - May 20 2004 : 4:57:42 PM
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bilgin65
Could you please explain what a mux is? Thanks.
Edited by - disco-fro on May 20 2004 4:58:42 PM |
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bilgin65
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83 Posts |
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YS
Nobel Prize Winner
USA
1132 Posts |
Posted - May 21 2004 : 9:12:37 PM
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The phone line has higher voltage than multiplexers can control. Normal voltage is about 50V and ring voltage may be 100V and more. So just using a mux is not a good idea. Besides, any device connected to phone line must have certain electrical properties.
So, I would think of getting two simple telephones and commutate them, maybe, with a relay. You need relays for hookswitches and relay(s) for mic/speaker.. think of it.
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bilgin65
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83 Posts |
Posted - May 22 2004 : 3:03:08 PM
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and so multiplexer control relays:)
bilgin65 |
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YS
Nobel Prize Winner
USA
1132 Posts |
Posted - May 23 2004 : 10:24:00 AM
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If you really need it. it's like "relay controls relay".
Also it seems to me that you kind of mix digital multiplexers and analog ones. The page you referred to talks about digital multiplexing; for the analog applications things may be slightly different.
In this telephone device, even the relays may be not needed - mechanical switches may do the job, unless disco-fro wants electronic control or computer control. In this latter case the computer may control relays via printer port, using methods described by Aaron.
Whenever you use analog muxes, make sure that:
1. commutated voltage is within power rails
2. commutated current it within limits
3. on-resistance of the mux will not degrade signal (for example, generally you can not connect a speaker via mux)
4. Leak through turned-off mux does not ruin your system (there are some tricks to be done if you deal with high-impedance or high-frequency signals)
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bilgin65
Apprentice
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83 Posts |
Posted - May 23 2004 : 4:10:44 PM
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I always refer to the idea of muxes. Of course i know that i can't control telephone lines via directly muxes. I want to say about mux logic. If disco-fro could understand this idea, he or she can solve the problem.
bilgin65 |
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YS
Nobel Prize Winner
USA
1132 Posts |
Posted - May 23 2004 : 6:03:34 PM
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Mux logic? what's that? same as switch logic, eh?
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bilgin65
Apprentice
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83 Posts |
Posted - May 24 2004 : 09:00:28 AM
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Hehe:)it was very nice:P
I wanted to say mux's logic: the idea of mux.
bilgin65 |
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n/a
DELETED (Inactive)
4 Posts |
Posted - May 30 2004 : 01:15:38 AM
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I mean: the simplest solution two old "telephone key". Or two small switch with center position. The center is OFF, one active position is "talk" another is"hold" for each line.
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cirvin
Nobel Prize Winner
USA
1542 Posts |
Posted - Jun 03 2004 : 8:40:57 PM
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quote:
The phone line has higher voltage than multiplexers can control. Normal voltage is about 50V and ring voltage may be 100V and more. So just using a mux is not a good idea. Besides, any device connected to phone line must have certain electrical properties.
So, I would think of getting two simple telephones and commutate them, maybe, with a relay. You need relays for hookswitches and relay(s) for mic/speaker.. think of it.
I alwase thought the phone lines ran around 12 volts off hook and rang at 50.
http://daxter12.topcities.com |
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YS
Nobel Prize Winner
USA
1132 Posts |
Posted - Jun 04 2004 : 10:56:29 PM
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As ou go off-hook voltage drops to about 7V. But the switch must be able to control all voltages in phone line. Also, tel. equipment must withstand about 1500V pulse and phones are tested for that - at least they should not catch fire.
So, Sebi is perfectly right - use mechanical switches!
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2-Line Switch
