Re: Re: How do I tell whether the phone's ringing?

["Luc Degrande" <luc.degrande@xxxxxxx>]

There will be some components required: an external modem has a
dedicated pin as "Ring Indicater". The level swings from
-12VDC to +12VDC, I suppose this will need conversion to TTL level
for connection to the input.
I have a simple circuit ( approx 8 components and wiring) wich will
do the trick. It uses an optocoupler with open collector output wich
probably can be used directly to the input if the input has an internal
pull-up resistor. There is no need for a power supply for this circuit.

Interested?
Luc.

----- Original Message -----
From: "Mark Harrison" <Mark.Harrison@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Wednesday, December 05, 2001 3:04 PM
Subject: RE: [ukha_d] Re: How do I tell whether the phone's ringing?


> Ant,
>
> That is a fantastically brilliant idea!
>
> I'm now kicking myself that I threw out a 2400 baud modem about a week
> ago

>
> Anyone got an old 9600 baud modem gathering dust that wants a new
> home????
>
>
>
> Mark Harrison
> Head of Systems, eKingfisher
>
> -----Original Message-----
> From: Ant Skelton [mailto:ant@xxxxxxx]
> Sent: 5 December 2001 13:52
> To: ukha_d@xxxxxxx
> Subject: Re: [ukha_d] Re: How do I tell whether the phone's ringing?
>
>
> Mark Harrison wrote:
> >
> > Hmmm... really wanted something that didn't involve a PC :-(
>
> You could use a modem plugged in to the phone line. When the phone
> rings, the modem will send "RING RING" out the serial port.
Not sure
> whether you can interface this to homevision, as I don't have one.
>
> My guess would be you either have an rs232 port (in which case you're
> laughing) or a TTL IO pin or somesuch, which might be tricker. To
> interface to that I guess you'd need to knock up a simple little
circuit
> - not sure if that's your bag or not.
>
> Although thinking about it, I don't thing modems send out anything
else
> down the serial port when they're quiescent, so maybe looking for
level
> changes on the modem's serial TX line would be sufficient.
>
> YMMV, HTH etc
>
> ant
> --
>                               /\/\
> ant@xxxxxxx                   (`')                  www.ant.org
>                                ()
>                     Megawatt Winged Avenger
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