My_work_Sample_ver1

Hi

This is a home project and the board is an old public phone circuit.

of course, there are other boards inside phone cases, but I have just two of them. this is the slave board of the two.

I accidentally funded them and started to reverse (back) engineering to make them my work sample.

I finished reverse engineering and schematic design and I've started PCB design.

Here is a brief description of what are the ICs on this board.

CMX605D4: an integrated telecom tone generator and DTMF encoder/decoder designed for ISDN interfaces, Wireless Local Loop, and analog to Digital Phone Conversion systems.

CMX631AD4: a low-power, system-selectable Subscriber Pulse Metering (SPM) detector that indicates the presence of both 12kHz or 16kHz telephone call-charge frequencies on a telephone line.

74HC273D: a high-speed CMOS OCTAL D-TYPE FLIP FLOP fabricated with silicon gate C2MOS technology.

and other ICs.