Aug 19, 2005 #1 Sobakava Full Member level 6 Joined Mar 27, 2002 Messages 350 Helped 8 Reputation 16 Reaction score 8 Trophy points 1,298 Activity points 3,342 I making an autodialer for handsfree operation. I could dial the number using DTMF generated by a microcontroller. This part works fine. I used a regular microphone from a phone handset for testing. I coupled it to the line using a 600 ohm transformer and it seems ok. But how can I combine : microphone, handsfree speaker and dtmf signal all together to the phone line?
I making an autodialer for handsfree operation. I could dial the number using DTMF generated by a microcontroller. This part works fine. I used a regular microphone from a phone handset for testing. I coupled it to the line using a 600 ohm transformer and it seems ok. But how can I combine : microphone, handsfree speaker and dtmf signal all together to the phone line?