Connecting DTMF Transceiver MT8888 to phone line

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acburiti

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mt8888

hi,

I dont know to connect the transmit block of DTMF Transceiver MT8888 to the phone line. I mean that I dont know what's the right interface for the line and this IC. There's an apllication note at: **broken link removed**

but just explain how to connect the receiver block. I wanna also connect the transmit block to phone line. So, how to do?

I really need somebody's help.
bye

antonio
 

I used a 600/600 modem coupler transformer to the phone line through a relay
used as the "hook switch". The secondary winding is grounded on one side and
other side connects to the receiver half of the 8888 through one capacitor and
2 resistors. At the "capacitor / winding" connection point, connect the "contact"
side of a solid state relay and the other "contact" to pin 8 of the 8888. I assume
you are able to write the commands that generate a tone. Activate the SSR just
before turning on the tone and release the SSR at the end of the tone. I used the
Clair LCA110 solid state relay. If this is NOT enough info, you can contact me
at dhewett@phoneline.kscoxmail.com .
 

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