lauren@vortex.UUCP (Lauren Weinstein) (11/13/83)
"Teltone" makes a very nice single chip DTMF (Touch-Tone) receiver chip which only requires a standard colorburst crystal to operate. The chip itself is relatively inexpensive, and at least part of the time some distributers offer a package of the chip and crystal for the price of the chip alone. Teltone Application Guide SC-1 contains a very complete discussion of DTMF and includes a number of schematics for interfacing their M-947 DTMF receiver chip to telephone systems. The guide also includes a schematic for a complete DTMF to ASCII conversion system using only three primary chips (M-947, a PROM, and a UART). --Lauren--