Dtmfout

[bearpawz]

Hi all, Can someone help with this?

I am using a pic16f819 and trying to use the DTMF out to generate tones. This is not for a sound application but just to make touch tone type sounds. Now the problem is... it sounds like garbage... does not even remotly resemble DTMF. I need it to sound like it would if you were dialing a phone. Any thoughts? I even tried the filtering schematic in the manual and no luck there. tried clocking the pic at 20 and still no luck. Im trying to avoid using the touch tone generator chip if at all possible... any help is appreciated!

[mister_e]

Hi, what kind of load are you using after the filter? If your load is too low, the filter will not work as expected. OP-AMP buffer is suitable after the filter. Also have a look to this thread http://www.picbasic.co.uk/forum/showthread.php?s=&threadid=68&highlight=dtmf%2A

hope this help

[Bruce]

Use at least a 20MHz oscillator. Below 20MHz it sounds pretty bad.

I built an auto dialer a long time back using DTMFOUT with only 1 cap & an 8-ohm speaker. It works great.

Didn't use any fancy filter circuits. Just 1 cap and a speaker.



10uF speaker
RB0 ----+-)|---------( )--------GND.

[bearpawz]

Thanks, I'll try it both ways. As far as the load, its either going to be an 8ohm speaker, or I may pipe it through a 386 amp.