Analog modem emulator?

[Ethan Dicks]

On 8/2/05, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
> >
> >...essentially simulates a telephone
> > network.... sold by Black Box.
> 
> I am surprised, but I have never seen a published schematic for such a
> unit, neither in a magaxine or on the web. They can't be _that_
> complicated, surely?

Having a) looked at competitors features, and b) built similar
products myself, the ones for sale are not simple.  Ours used a pair
of SLICs (Subscriber Line ICs) just as a proper PBX or Telco switch
port would use.  In between a few sq in. of through-hole passives, we
had an 8048-type microcontroller generating dial tones, interpreting
telephone numbers, triggering ring voltages, etc.  Ours, being two
lines, fit in a standard Pac-Tec box that was about 6" x 6" x 2" and
was *covered* in parts.  SMT could have made it cheaper, but it was
designed in a non-modern environment for low-volume production.  We
didn't make enough to fill a shopping cart.

-ethan