AVR-Chat

Re: [AVR-Chat] Source of Caller ID Chips

Kathy Quinlan wrote:
> Peter Gargano wrote:
>>This thread reminds me of a project I'd like to start (if I had the time). I 
>>want a simple, intelligent, 3 (up to 8) line PABX (Private Automatic Branch 
>>eXchange) using "normal" phones.
>>
>>Maybe someone has seen a DIY PABX somewhere?
>>
>>Peter
> Yeah, I have designed many PABX's over the years, Some used special 
> handsets, others stock standard 48V handsets.

I was thinking of something simple that (if possible) used the standard AU 
Telstra phone (ie. 48V tone dial). All I'm after is something that would allow 
anyone to pick up a call on one or two lines, and transfer it to another line 
(up to 7 other lines).

To be honest, I have not done any homework on what's required to do this. I 
figured someone else had maybe done something similar that could be adapted, 
so I didn't have to start out from scratch.

And yes, I know the biggest issue is one of safety, and I was thinking that it 
could be powered from a battery that could be recharged periodically, so no 
direct connection to the mains. A 5 or 6 Volt to 48 Volt supply is pretty easy 
to organise.

> First you need to decide what you want, as some features are not easy to 
> impliment without custom parts, my last one I designed for a specific 
> aplication used SLIC's (Subscriber Line Interface Circuits) out of an 
> old NEC PABX (D3 or in au Telecom system 120) as these handle all the 
> line conditioning, ring and tone switching etc.

Kat, are any of these designs in the public domain?

Peter Gargano