Using cm8870-kt3170's Opamp out

[cozturk]

cm8870

My circuit already contains cm8870 for DTMF decoding.

I want to use its opamp output to my mcu input for detecting other tones (call back, dial tone etc). Is the Is it posible?

Opamp out is about 5Vpeak while tone occurs?
PS: I don't have scope :|

 

[artem]

cm8870 circuit

Opamp output depends on diff input voltage and gain.
There are some forumals in data sheet to set a gain ,

So the only question foy you is to know input voltage. Try to measure tone voltages AC by multimeter at GS pin .

 

[cozturk]

kt3170

Ok. thanks.
I found a nice projects for decoding DTMF without kt3170. If some friends interest it, The project here:
**broken link removed**
This circuit uses PIC's comparator. For detecting DTMF tone.

 

[artem]

cm 8870

BTW there are a lot of similar projects - just try to search this forum for CID - caller id.

Good luck.

 

[zolam]

cm8870 projects

8870 is dedicated to DTMF detection and has all the appropriate filters for the DTMF frequencies only built in
DT and other tones are quite different (about 440HZ modulated vs. a pair of fixed frequencies in the range 697-2000HZ for dtmf)