On Jun 18, 10:53*am, "hr(bob) "
wrote:
On Jun 18, 9:52*am, spamtrap1888 wrote:









On Jun 17, 5:33*pm, "Arfa Daily" wrote:

"mike" wrote in message

...

On 6/17/2012 4:32 PM, wrote:
I want to put an LED to test my phone line, which I found to be ca 50v.

Where/how do I find the right LED?

THe LEDs at Radio Shack are all like 2v (yea I remember VCC of 2.3 on
diodes
in my EE2 for non EEs course).

Should I just use a regular bulb, like the kind used for Christmas
lights,
instead? (what about the LEDs used for CHristmas lights? Shouldn't they
work?)

Besides, I really only want ONE LED.

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A series resistor will answer your question.
Assume you now all about what happens when you load a phone line.

And of course what happens when a ring signal appears across the line ...

Reminds me that back in the day, the radio studio phone had two lights
that flashed instead of a ringer. The lights looked like a salt and
pepper set. Maybe the OP could put a neon lamp across the phone line.

It depends on what he wants the leds to do, light up the room, or only
light up when the phone is ringing.

If he wants it to light up the room, he'll have to protect it when
ringing voltage is present on the line.

*50 years ago I designed the telco
circuits that detected when a customers wanted service. *It was a pain
to distinguish between a real off-hook from the customer and line
leakage due to poor cable insulation, squirrels, etc.


I had an old Automatic Electric phone containing a pot marked off in
terms of distance from the CO. I guess there were some long loops in
the rural areas served by the independent telcos who were Automatic
Electric's main customers.

Here's a picture of one of the "saltshaker" ringer lamps. Although
this one is stuck to the dial of a dialless phone:

http://wwwdelivery.superstock.com/WI...98R-239648.jpg