Hi Skarr,

If you put a relay in the circuit as indicated then you wouldn't need to plug and unplug your circuit to the phone line. Your program would include a line to turn the relay on such as:

PortB.1 = 1 'turn line seizure relay on

Then when you are ready to disconnect from the phone line you would program:

PortB.1 = 0 'turn line seizure relay off

Line seizure refers to a relay that disconnects the house phones and connects the phone line to the dialer. This prevents someone from picking up the phone in an attempt to block the call. Then there is another relay with contacts in series with one side of the phone line that would be closed then the dialing would take place. When the phone call is completed, then both relays would be turned off. The phone line is returned to the house phones until the next call out.

You will need to drive the relay circuit with either a transistor or with a driver package like the ULN2003 or ULN2004.

I have been in the alarm business for a long time and I am quite familiar with dialers and their circuitry and inner workings. I finally decided I wanted to design and build one of my own just for the heck of it. I am in the beginnings of the design phase and will be happy to share ideas with you on this. I've been getting other work related projects out of the way so I can focus more on the dialer project.

HTH,
BobK