HOW TO RELEASE PHONE LINE ??

[jrgmayo]

HI..
I AM DESIGNING A PHONE LOCK...
MY ASK IT IS:
HOW I CAN RELEASE THE LINES LOGICALLY..DON´T USE RELEY OR EXTERNAL SOURCE. ?????

I PLAN TO USE A PIC16F84A THAT FEEDS DIRECTLY OF PHONE LINE..

THANK YOU..

EXCUSE MY ENGLISH..

ESPAÑOL:

BUENOS DIAS..
ESTOY DISEÑANDO UN CANDADO TELEFONICO...
MI PREGUNTA ES:
COMO PUEDO LIBERAR LA LINEA LOGICAMENTE..SIN UTILIZAR RELEVADOR NI FUENTE EXTERNA. ???

PIENSO UTILIZAR UN PIC16F84A, QUE SE ALIMENTA DIRECTAMENTE DE LA LINEA TELEFONICA..

GRACIAS..

 

[David Bridgen]

Perdoneme que no tengo otro idioma instalado, por eso no tengo las letras con los acentos.

La tomada de la linea consiste en conectar una resistencia de aproximadamente 600 ohms, (que en la practica puede ser bastante mas.)
La liberacion consiste simplemente en desconectar dicho resistencia.

Si puede conectar algo con una resistencia relativamente alta, como un dispositivo de vigilancia o monitoreo con impedancia como 10k sin que la linea sea tomada.

Saludos.

 

[Dialtone]

Wow David
Your spanish is good. (So was the answer.)
Didn't realize spanish was widely taught in UK. Most impressive.
Dialtone

 

[zachtheterrible]

I can't believe it!! My spanish 1 that im getting taught in school covered a lot of that!! I actually understood it pretty well :lol:

 

[Dialtone]

Newsflash Zac
All that stuff they are (or will) try to cram in your head in school that you think you will NEVER use, just may come in handy some day.
I remember getting taught number bases in 7th grade. Thought it was a real waste of time since we only used base 10 in math.
Later in life I went into computers and when they started teaching binary and octal and all that stuff came flooding back to me. I had less trouble understanding it and doing conversions that others in the class who had not been exposed to it before.

PS those geometry formulas also come in handy in everyday life too.
Examples:
1. Calculate how many cubic yards of concrete are necessary to pour a foundation slab 60' x 40' x 4' depth
2. What is the angle of a rafter cut when the roof pitch is 4 in 12
3. What is the 3-4-5 rule (hint: formula for figuring the hypotanuse (sp) of a right triangle) C= square root (A squared + B squared)

Why would you ever need these formulas? Try building a house without using them.
Dialtone

 

[Nigel Goodwin]

Didn't realize spanish was widely taught in UK.

It's not :lol:

They do Spanish (as the only foreign language!) at my daughters school, but this was only because they allowed the entire student body to vote on which foreign language they wanted in school. Spanish won by a large majority!.

Usually, French and German are the two choices - at the grammer school I went to, Latin was an option as well.

 

[David Bridgen]

Your spanish is good.

I spent a lot of time travelling to South America and was resident for several years too. Didn't learn it formally. I just picked it up early on. Taught army techs in Spanish.