Found this very useful

http://www4.tpg.com.au/users/talking/DialAlarm-1-Page1.html

----- Original Message -----
From: "Patrik Husfloen" <u58611234@TELIA.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: 06 July 2001 04:01
Subject: Re: [EE]: Telephone gyrator


> I have one of those, well, I got it from a friend who used to work at a
big alarm/security company, it has an eeprom which stores 9 numbers which it
calls in sequence, and then it "beeps" this special sequence, optionally you
can have it send a pre-recorded msg to each phone number.
> it's programmable from any phone, ie you hook it up to the line, and use
your phone to program it with DTMF..
> I never used it, I have manuals and everything for it, it looks rather
simple
>
>
> ----- Original Message -----
> From: "Jeszs" <jgonzalo@RECOL.ES>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Thursday, July 05, 2001 10:21 AM
> Subject: [EE]: Telephone gyrator
>
>
> > Hi everyone!
> >
> > Months ago I built a home alarm to call my mobile upon intruder
detection.
> >
> > Main parts:
> > - 16PIC84
> > - MT8880: DTMF recognition and generation
> > - 600 Ohm transformer to interface the phone line
> >
> > I had many difficulties to engage the line and send tones through it but
finally I found the concept 'gyrator' and built one as per a web page
recommendations.
> >
> > Today, summer in Spain, the machine is failing. Sometimes it works ok
and sometimes my phone company operator says the dialled number is not
correct.
> >
> > Do you know a 'standard' way to attach the line to the transformer and
the transformer to the MT8880?
> >
> > Thank you very much in advance!
> >
> >
> > --------------------
> > Jeszs Gonzalo
> > INSA, Ingenierma y Servicios Aeroespaciales, SA
> > Paseo Pintor Rosales 34
> > Tel: +34-915489149
> > 28008 Madrid (SPAIN)
> > --------------------
> >  xm6Y   0~~o-+-}J&?)m}:%y+^6   "b2YsS[h~~o-+-~il9; .&^~7*9k-~h->f s+
>
> --
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>
>

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