[GreenKeys] Telephony museums

[greenkeys@mailman.qth.net]

This brings up one of my favorite complaints.  When I was a kid you could
go to the telephone business office and they had a rack of booklets there
you could take, and one explained how telephones work.  You know, carbon
granules and that modulates the current from a battery and that modulates
the magnetic field attracting a diaphragm, etc.

How are we ever going to explain to our grandchildren how a telephone
works?  We start out with this electret microphone, and because C=Q/V
when the diaphragm moves and changes the capacitance that generates
a voltage that can be amplified.  Then we sample it and turn it into a
string of numbers...