How to connect microcontroller with a generated DTMF to a phone line?

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Re: dtmf problem!!

Hi,
I am sorry, I am unable say anything by viewing the plot, but if all digits (0 to9) BCD outputs you could get from 8870 with your signal input, your signals are ok. Please increase the duration of ON/OFF to 200 msec.each and try it on the phone line again. By the way what are the two plots shown on the oscilloscope ?

Regards,
Laktronics
 

dtmf problem!!

the yellow is analog tone after filtering the pwm that ucontroller generate

the blue is noisy tone signal

the pink is original dtmf signal that the ucontroller generate .

thanks.
 

dtmf problem!!

try this


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    segmex

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dtmf problem!!

Can i use LM324 for Op-Amp Or NOT....
 

Re: dtmf problem!!

look at this one
 

Re: dtmf problem!!

why do you need an inverting amp, how about a non inverting one ?

ken
 

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