Exclusion by Modem (1)
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Remember taking the Mac for an afternoon spin on the web when that one click and every one after did nothing? You glance at the carrier light on the modem and it is dark. You think "what on earth?" Shortly you get the innocent question posed to you, "Was that you using the modem?"When the truth comes out somewhere in the house they picked up the phone and knocked you off your PPP session. We can fix that. About $10 in parts and a few minutes reading and you are set.
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Before we get started we have to set your & my mind at ease by getting some fundamental facts of safety out of the way. Please read the caution at the bottom of this page.
A few things should be known before starting. A brief outline of events:
- Be certain of the modem's location to be used for the project. I say this because if the current location is not the best choice, lets get a new cable to the optimum location. A few minutes of planning will be very helpful in the future.
- The location of the modem has a cable going to the common connection point within the dwelling (perhaps you have just placed a cable) and at the common point this cable must be isolated. That is you must determine which cable is the correct one going to the modem jack(s).
- Perform the jack alterations.
- Perform the wiring alterations at the common connection point.
- Perform a final test. This can be easily done by plugging a cord from one jack to the other at the modem location. This is a good point to remember if you sometimes remove the modem from this location. The test would be thus:
Without the modem or test cord in place, all phones would NOT be working. With the cord or modem within the circuit ALL phones would be fully functional.
- Job well done, pat self on back, brag freely about the job.
The 6 steps above will be discussed in some detail on the following pages.
First take a moment to gawk at your modem (if it is an external type) and compare it to the simple diagram presented.
Figure 1
Simple as it is the idea here is the modem has 2 jacks on the rear for connection via miniature telephone plugs, one for incomming line and the other for the use of a phone through the modem. Rather than have a phone plugged into the second jack we will have the rest of the phones in your abode operating via this connection. OK.
Again when the modem is in use the connected phones to the second jack of the modem will not function. When the modem is not in use or powered off the rest of the phones will operate normally.
If your modem is an internal type that has the second jack, this is exactly what we need. At all times the modem we are talking about is the standard analogue modem that uses a conventional analogue phone line with a RJ11, RJ11A, RJ12, RJ14 type of supplied wiring for interconnection to the telephone network. If you have a RJ31 or RJ31x type of connection please write and we can discuss this as well. What this project is doing is exactly what the RJ31 type of wiring is doing without the purchase of said hardware. The RJ31 type of wiring is much more expensive and not too commonly available. Remember the RJ designation does not at any time relate to the type, style nor size of jack it is how it is wired.
I cannot stress enough the need to be observant when working on live circuits and the possibility that although the voltages may not appear to have a potential to cause harm you should take steps outlined below to protect yourself and loved ones.
The greatest danger when working on any project is not so much the project but the effects of the project. If the telephone circuit is touched by bare hand no noticeable effect is apparent, but if the line is being called at the moment of contact, this will get your undivided attention.
Some specs: Normal telephone operating voltage is about 40 to 52 volts DC. When the phone is ringing you can expect to have upwards of 100 volts AC. Not all locations are these exact measurements as dependant on the distance you are from the source and the integrity of the circuit. The currents vary as well with the type of connection, the line length, and possibly how it's delivered typically measure 20ma as a minimum.
Before starting any project it is well advised to become familiar with the scope of the endeavour. The library is always a first choice for information and if still in doubt consult the pros. Naturally if completed correctly the use and safety would be nothing more difficult than your telephone is now.
D2M © 1997 1998 1999 MacMcLellan A graduate of Curmudgeon Emeritus.
Legal types everywhere will thank me for these few notes of caution:
The danger here is if you have a tool in your other hand and with the reaction of comming in contact with the "ringing voltage" this tool may likely go flying. The vocabulary used to describe the incident could also be harmful to your audience. DO NOT stand in a pool of water with bare feet and wet your fingers to try and experience the maximum effect of this.
Please be careful. I don't want to make this appear as a truely dangerous feat but a little caution is required.
As a reminder for any undertaking involving Mr. Edison's, Mr. Franklin's and Mr. Bell's discoveries, remove the power or disconnect the source before you "Poke somebodies eye out".
If there is a raging lightning storm in your area at the time your project is underway I would hope you have the sense to sit it out. Not that anything is going to happen if a strike is near you but the law of Murphy may or may not be in effect. Often the telephone service protector is located close to the area where some work will take you and if the accidental compromise of this should occur I would ill advise being near it during a storm. Sometimes all that happens would go unnoticed but if an extreme case rears it's head you could soil your laundry.
If you are uncertain about any of the techniques or ideas presented, please take the time to write. Please be patient in expecting an immediate reply ...Don
The counter below sets a cookie to let me know what browser you are using and the OS of choice. This is one way I can best keep my html current for the average Mac'ster. Agreed.
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