Hi my friends;
Please help me!
an article at ieeexplore:
"The TDA1077-an I/sup 2/L circuit for two-tone telephone dialing"
Unfortunately I cannot download it...
The circuit-design aspects of an integrated circuit to perform two-tone telephone dialing are
described. The circuit is believed to be unique in that it combines both the crystal-controlled
frequency synthesizer and the output amplifier on the same chip. Moreover, no external power
supplies are required; the circuit is powered by the telephone-line current. Designed to require a
minimum number of external components, the LSI chip provides an economical and accurate
two-tone dialing unit. A typical application circuit for existing telephone apparatus is shown and
aspects of future development are discussed ...
Please upload this PDF to a file sharing site eq. ifile.it or ...
Thanks a lot!