[VoIP] Old Tone Project

[David Josephson]

Doug Alderdice wrote:
> Thanks to all who have dialed into the switch this afternoon and 
> evening.  I have just returned the switch to its original single tones of 
> 200 Hz dial tone and 400 Hz for busy and reorder.
>
> Definitely have proof of concept for this digital recording idea.  Now I 
> have to build the board that will be installed on the switch.  That's going 
> to be set back a bit as I need 28-pin IC sockets for the recorder chips, 
> which I don't have (thought I did) and Radio Shack no longer carries much 
> of anything useful in parts any more so I can't run out to the local RS 
> store.  So I have to do a mail/web order from somewhere.  If it takes as 
> long as my recent order from Jameco (5 weeks with poor communication from 
> their customer service dept), it will be a bit before I can even begin to 
> build this thing in a more permanent fashion.  Stay tuned.
>   
I probably have several metric fistfuls of 28 pin sockets. Where do you 
want them sent?

Also, wouldn't it be more interesting to develop an analog tone plant? I 
did that for a homebrew crossbar exchange many years ago, using low 
noise opamps in a Wien bridge with switchboard lamps for the ballast. 
Using a single transistor to generate two tones, a la touchtone dial, is 
also a possibility.