how to build a message indicator light...

[LYHTSPD]

does anyone know how to make your own indicator to let you know when you have voicemail messages? we have them on our phones in the residence halls at the university i attend, but i want to make my own. does anyone have a clue on how to or where i can go to get information? thanks!!

-Lyht

 

[Pastore]

bump for ya... neat idea

 

[Valhalla1]

voicemail messages, like on your telephone? you'd have to write software to interface with the phone network, which logs in and checks your messages and turns on the light if you have any

 

[Train]

just crack open one of the dorm phones and see what makes it tick

 

[LYHTSPD]

you dont need any kind of software to interface with anything... i have been messing with it and this is what i found. using a DMM, the voltage across the only two pins that are being used (the middle pair) is about 50 volts dc when there is no message. when there is a message, it pulses from about 50 to around 100-115 volts dc. the light is created by a single led. the voltage at the led pulses from 0 to 1 volt dc when there is a message. the only thing is that i cant get a current reading at either place to figure out what kind of resistors i need.
i acquired a little flasher that lights up when the phone rings about 2 years ago. that uses a small neon bulb to create the light, but it does not flash when there is a message....

 

[Passions]

Why use a DMM when you can use your tongue. After a while you can find the voltage quite accurately.

 

[LYHTSPD]

hey, not funny.... how do you think i discovered how the telephone worked

 

[DaLeroy]

Have you tried getting the current reading at both places by putting the ammeter in series? Otherwise, just test the resistance and go from there...

 

[axelfox]

Man, what a bunch of cool nerds

 

[Phil21]

Am I missing something?

Since you know the amperage, create a relay-circuit, that turns on the LED when the amperage gets into specified ranges.. Why do you need to know the current supplied to the LED on the current device?


ok.. nm. I guess if you don't want a battery you'd need to know that huh. But, if you don't care if it needs a battery.. shrug.

-Phil

 

[LYHTSPD]

i dont know the amperage... i know the voltage. the amperage cant be much because when i did accidently chew on the phone cord and shock myself... twice... it didnt hurt very much. i thought about the relay circuit but i dont want to start throwing more components in there than i have to.

...and yes, we are a bunch of cool nerds!!