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DTMF output form mobile(nokia 2626), what will be the voltage of the signal?

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dss91

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hai here i have a peculiar problem

i have taken the dtmf output form mobile(nokia 2626)

what will be the voltage of the dtmf signal???


i hav kept a voltmeter at the mobile jack to measure the output voltage from jack
it reads zero?????

ok leave that ihav two wires from the head set one is a red one and other black one how should i connect them this is my first doubt

i hav connected the red wire from headset to pin2 and black to ground

and i hav dialed it and checked the pin stD for a logic high and i got nothing

even at the output pins i havnt got nothing

i hav attached my circuit verify it

 

problem with dtmf

well.
try to change gain of preamplifier resistors of 100K because gain in your circuit=1 so the voltage of dtmf signal must be bigger enough to tigger the MT

for example try 1M by 10K
 

Re: is it 8870 or the jack teasing me help me plzzzz

sorry i havnt got your point do you want me to change the resistor next to capacitor by greater than 100k ,i think that would certainly stop the dtmf

or the resistor to pin3

plz suggest me in detail
 

mt8870 basic application

look at the schematic .. maybe it helps u.
 
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    sreein

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Re: is it 8870 or the jack teasing me help me plzzzz

i got your point
ok i l try that
thanks for your help
 
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    sreein

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Re: is it 8870 or the jack teasing me help me plzzzz

is it work
 

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