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[SOLVED] telephone line dtmf tone decoder using mt8870

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sreein

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how can interface telephone line with mt 8870?
 

nikhilele

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mt8870 is easily interfaced with phone via rc coupling ckt
...
just go through this ckt
 

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sreein

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thanks
But i need to interface mt8870 with a telephone line that's voltage vary above 100Volt during ringing.This may damage my circuit,how can i prevent this?
 

nandhu015

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Disconnect the mt8870 circuit (using a relay) till the phone is off hook.
 
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sreein

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Please provide that circuit
 

tyty123

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You can use another schematic, without a relay.
I used this schematic and it works perfectly.

---------- Post added at 22:22 ---------- Previous post was at 22:21 ----------

 

sreein

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thanks...
i will try it ..
 

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