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help me.

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planetajay

New Member
i require the datasheets for the following I.C.s:
CD4049
CD4013
74154 (4-to-16-line demult-iplexer)
also can someone help with the explanation for the functioning of the various parts of the circuit shown below.
 

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Sebi

Active Member
KT3170 is a Samsung-clone of original MT8870 from MITEL.(today is Zarlink Semiconductors) It's a tone decoder with BCD output.
 

Chippie

Member
the tone decoder outputs to the 154 which in turn selects the relevant 4049 gate dependant on the state of its inputs.....the 4049 outputs then feed into the 4013 ff and operating the relays......so in essence you can remotely switch on and off loads by using a tone down the telephone line presented to the input of the tone decoder.......errr thats a basic description........any one wanna go one further, feel free :)
 

Sebi

Active Member
One thing i not understand: why go this circuit to receive mode? I see the relay, who switch a 200ohm resistor parallel to line, but what circuit make it pulled state. (off hook position)
And what is the 10kHz injection?
I think, this is only a part of the circuit, additionally You need a ring detector with optocoupler, or can parallel work with answering machine or FAX.
 
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