US Telephone Systems, Basic Stamp
knightofoldcode
Posts: 233
Board,
I'm interested in being able to use a BS2 to determine the status of a Phone line, IE, is someone else in the house using the phone? Is there an incoming ring, Is the phone line connected, etc, etc. I've looked around for this kind of information and can't seem to find anything anywhere. The Cermetek modem won't do what I'm looking for. I need the ability to actually tell the status of the line, if it's in use, connected, etc, the Cermetek Modem can't tell me that kind of information. From what I can tell the telephone line when it's taken off hook it's voltage drops, maybe some kind of a A/D would be needed? Hopefully someone else knows how to do this because I'm clueless. Even just a point in the right direction of a webpage that might have some information I'm missing.
MUCH TIA,
Knight.
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I'm interested in being able to use a BS2 to determine the status of a Phone line, IE, is someone else in the house using the phone? Is there an incoming ring, Is the phone line connected, etc, etc. I've looked around for this kind of information and can't seem to find anything anywhere. The Cermetek modem won't do what I'm looking for. I need the ability to actually tell the status of the line, if it's in use, connected, etc, the Cermetek Modem can't tell me that kind of information. From what I can tell the telephone line when it's taken off hook it's voltage drops, maybe some kind of a A/D would be needed? Hopefully someone else knows how to do this because I'm clueless. Even just a point in the right direction of a webpage that might have some information I'm missing.
MUCH TIA,
Knight.
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Gravity doesn't exist. The Earth sucks.
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Make a man a fire, and he will be warm for the night.
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Comments
IF it doesn't have that option, a regular modem does....get an old surplus external one and hack it!
Modems will also give the "RING" indication when a call is incoming.
I'm on my MAC and don't have any docs on here....google some modem specs/manuals and see what the old buggers can do!
USR Sportster 14.4k is a place to start.
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·
Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
PUT A CHEEP DIGITAL OR ANALOG VOLTMETER ACROSS THE LINE.ON HOOK WILL READ ~ -48 VDC AND OFF HOOK WILL READ ~ -12 VDC .
W A R N I N G REMMEMBER IF YOU ARE USING EQUIPMENT WHICH IS EARTH GROUND, THE TELEPHONE IS GROUND AND -48 VOLTS OR """ BELOW GROUND """.
I WILL TRY TO FIND SOME MONITOR CIRCUITS FOR YOU FROM MY REFERENCE FILE.
73
SPENCE
K4KEP
Post Edited (SPENCE) : 10/27/2005 3:56:55 AM GMT
http://www.tkk.fi/Misc/Electronics/circuits/teleinterface.html
http://www.piclist.com/techref/pots.htm
http://www.micromint.com/products/rtc_dtmf.htm
http://www.73.com/a/0552.shtml
http://www.digitalproductsco.com/
http://www.broadcastboxes.com/mpc-2.html
http://www.callerid.com/whozz2.htm
http://www.users.bigpond.com/PASCOM/
http://www.web-ee.com/primers/files/AN812_1.pdf
73
SPENCE
K4KEP
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Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
In some of your information, I've been able to find a IC that might do what I need. IT'll be a much larger IC count than I wanted, but it'll ahve to do.
Steve,
The Ceremetek modem, or any modem for that matter (any that I've seen) don't actually tell you when the phone is off the hook. What I'm trying to do design is an alarm system that, if the phone lines are cut, will indicate that information. I'm doing some much more sneaky stuff with whats done when it detects a cut phone line, but basically that's the part I need to work out. Because of the information I need, I can't have a modem checking every 2 seconds to see if it's cut, that would essentially be impossibly to use the phone for anything but the alarm. I appreciate the information though! [noparse]:)[/noparse] And I will be using a modem as well as this supervisory circuit. [noparse]:)[/noparse] As for the FCC and the regulations on anything on the phone line, this IC that I mentioned above, has full FCC registration for usage on phone lines. [noparse]:)[/noparse]
Again, I think I have the information I need, but it's a much larger IC count than I want.... IC/component. At current inception, it's something like, 2 IC's, 16 resistors (and 1% resisters at that), and 1 capacitor. It's less than the ideal solution, but sometimes the solutions isn't already there. [noparse]:)[/noparse] The schematic is on page 5 of the datasheet located here.
IC's:
CPC5710 made by Clare. (Digikey Part Number: CLA169-ND)
LM339 Quad Comparator.
If anyone has a better idea though, I'm open to suggestions. [noparse];)[/noparse]
Knight.
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Make a man a fire, and he will be warm for the night.
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Post Edited (PJ Allen) : 10/27/2005 11:23:52 PM GMT
http://www.broadcastboxes.com/mpc-2.html
THIS INTERFACE MODULE IS FCC REFISTERED AND APPROVED. WITH IT YOU CAN USE UNREGISTERED MODEM CHIPS. OR OTHER AUDIO DEVICES. IF YOU SELECT IT REMMEMBER TO SELECT 12 OR 5 VOLTS FOR THE RELAY. I USE THIS DEVICE TO KEEP ON THE RIGHT SIDE OF THE LAW.
SPENCE
K4KEP
indeed, you'd have to have the modem check for dialtone every couple seconds to see if it's cut.
Like PJ said, an opto would allow for easy connection to a stamp pin....or even any old LED if you have a photocell and a schmidt....however, your count is getting higher and higher!
On alarm panels they use a resistor inline. The idea is that when the panel no longer sees this resistance, then it reacts. If it sees an open, it goes in to alarm for wire cut....not sure if it alarms for a short (as in someone trying to bridge a wire or fake out a switch)....
IF you had extra pairs in the phone line and expected the entire line to be cut, then use the spare pair....just another option, if feasible!
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Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Yeah, it's probably possible to use a second pair in the wire, but this is an alarm, and I want to make sure that it also has access to the phone line itself. [noparse]:)[/noparse] Also, this *might* come to market.
I'm kinda having a hard time understanding the way a conventional panel uses a inline resistor to check for the presence. Cpuld you please elaborate? I'm already going to have a conventional modem, and if I use the IC mentioned in my previous post, it allows access to the line, while still maintaining the FCC's permission, which was already obtained by the IC's creater, Clare.
Much thanx or all the help so far, btw!
Knight.
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This message transmitted with 100% recycled electrons.
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Gravity doesn't exist. The Earth sucks.
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Make a man a fire, and he will be warm for the night.
Light the man on fire, and he will be warm for the rest of his life.
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I apprecaite the link, but I'm going to be doing this on 3 hours to start, that's alot of money for those devices. [noparse]:([/noparse]
Knight.
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This message transmitted with 100% recycled electrons.
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Gravity doesn't exist. The Earth sucks.
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Make a man a fire, and he will be warm for the night.
Light the man on fire, and he will be warm for the rest of his life.
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It's been a while since I've worked on alarm panels and I've long since tossed the manuals....
But as I recall...the idea was to use a resistor somewhere around 22kohm (or 220kohm) and that this would then give you a decent current draw through that particular line.· If the current draw stops, it means your lines been openied and that you should go in to alarm.·
IF the current goes infinite then the lines been shorted.....now the thing to remember, is that the resistors are SUPPOSED to go across those little door reed switch contacts....but a lot of installers put them in the panels cuz there just isn't any room in the reed switch covers.·
I don't know how the panel sensed the current change....but you might try putting in a zener and an opto or something to give an indication of the current change.·
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Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Steve,
I don't know if we are talking about the same thing. I assume the resistors you're speaking of are used for detection of a closed loop system, used in the actual zones of the alarm, right? Not for detecting the presence of a telephone line, right?
I'm familiar with the method of detecting if someone has tampered with the lines by directly shorting the alarm leads for that particular switch, by placing a resistor in the switch.
Knight.
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This message transmitted with 100% recycled electrons.
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Gravity doesn't exist. The Earth sucks.
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Make a man a fire, and he will be warm for the night.
Light the man on fire, and he will be warm for the rest of his life.
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Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
I gotcha. [noparse]:)[/noparse]
Knight.
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This message transmitted with 100% recycled electrons.
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Gravity doesn't exist. The Earth sucks.
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Make a man a fire, and he will be warm for the night.
Light the man on fire, and he will be warm for the rest of his life.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-
The (TLM) Telephone Line Monitoring used by most alarm panels is MON. via software. It is checking for dial tone at set periods of time defined by programing. In short the panel picks up the line and checks for dial tone. We program our checks at odd hours of the day and we also set our fail rates to like 6 meaning that the panel will check every 5 mins after the first fail for 6 times before the panel will indicate a trouble condition. Have never seen a line checked by EOL.
MIke
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mike@losteagles.org
www.losteagles.org
Recon,
Thank you for the information.
I hadn't realized the panel would actually pick up the line and check every so often. It sounds like a bad method of detection. And, unfortunately, won't work for my method of the alarm system. I have two phone lines in my house, and I want it to be slick enough that if one is cut, it'll automatically go to the ohter line and call my cell phone, if both are cut it uses the cellphone built into it to call my cellphone, then the police station. [noparse];)[/noparse]
I don't think it's really possible for the EOL to detect a phone line status. Steve was getting confused on _what_ I wanted to detect, he was misinterpreting the zones as being what I wanted to detect, and not the phone line. However, I do want to check the status of the phone line.
So basically, I can't steal the method from previously built panels. [noparse];)[/noparse]
Knight.
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-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-
This message transmitted with 100% recycled electrons.
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Gravity doesn't exist. The Earth sucks.
-=-=-=-=-=-
Make a man a fire, and he will be warm for the night.
Light the man on fire, and he will be warm for the rest of his life.
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