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Telephone Status LED

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In this thread I am going to talk about build a status indicator for the telephone line. It will do is tell you if someone's on the phone, off the phone, incoming calls, and if the phone line is working. Why whould you want this device? Well, lets say you have 2 phones in your house and you want to know if someone is using one, or if you need to test the phone line to see if its working.

What you will need is.
1 Rectifier diode (It should not matter which kind you use)
1 12 Volt LED
2 33KΩ Resistors
1 telephone cord
Something to cut-and-slice the telephone cord. :)

Optional components
1 180KΩ Resistor (This makes a better dim, you can ignore it if you want to)
Those parts you can find at AllElectronics.com

Here is the blueprints
**broken link removed**

Contact me by email delphijustin@mail.com , if there is any problems,
NOTE: Phone cords may have different color-coded wires.
 
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I can tell you my local phone company would find this device, and flag it as a problem. They would disconnect my phone until I removed it, and charge me for a trouble call...
 
The problem is the continuous DC current drain imposed across the phone line. The telco searches for "leaks". If they see the continuous leak from the central office, they assume it is moisture in their cables. They will send out a troubleshooter. When they figure out that it is something inside your house, they will disconnect the lines outside your house. The tariffs allow them to charge you for the trouble call.
 
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When phone rings the LED is likely to get spoiled by 75V reverse break down during one half cycle, though no current flows. Same is the case when people apply LEDs directly on mains without reverse protection.

It would better to have the other diode across the LED in reverse direction.
three resistors not needed.
one single would do to get few mA not to reach detectable level (perhaps designer's limit would be around 4 mA.)
 
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phone line status indicator

I built a simpler system which doesn't overload the phone line line as much as yours.

100uA VU meter
bridge rectifier
470 k ohm resistor

The meter shows you all 3 line statusses.

There is a clip on youtube which shows the full workings of it.

Look under phoneline status indicator.
 
I built a simpler system which doesn't overload the phone line line as much as yours.

100uA VU meter
bridge rectifier
470 k ohm resistor

The meter shows you all 3 line statusses.

There is a clip on youtube which shows the full workings of it.

Look under phoneline status indicator.
i appreciate. but perhaps this is a simplest visual indicator with a low current LED though.
The O P has almost same design, that I was trying to refine.
 

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