[VoIP] Old Tone Project

[Doug Alderdice]

At 05:27 PM 3/25/2007 -0800, David Josephson wrote:
>I probably have several metric fistfuls of 28 pin sockets. Where do you
>want them sent?

Thanks!!  I'll contact you off-list.  I was just shopping around a couple 
of online places and of course everyone wants $25 minimums, or nails you 
with big shipping and handling if you aren't at $25.  I just got a 
decently-sized order from Jameco so don't need much more at the 
moment.  Still kicking myself that I didn't verify whether I had those 
sockets or not.

>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.

Yes, analog would be a way to go, too, and more prototypically correct, as 
they say.  Chuck Richards, who has a step switch but not on CNET, has 
reportedly developed all of his progress tones using the old 2206 modem 
chips.  I haven't heard what they sound like, but he claims they're pretty 
good.  He claims to even have decent "hiss" on the ringback tone akin to 
the sliding contacts on the mercury drums.  I have a couple of 2206 chips 
kicking around here, I could try to duplicate that approach, too.  But, I 
had the ISD chips on hand by the time I learned of Chuck's method, so 
decided to keep with it.

I somehow got on the digital track here.  Also, my electronic skills (or 
more accurately, lack thereof) show their limits when digging too deeply 
into oscillators, opamps, and the like.  I do better with digital...  Also, 
the parts count is proving to be pretty low with this recording chip approach.

Doug.