[GreenKeys] Sighting

[Jim Haynes]

Well in my childhood the public library had a very old edition of the
Boy Electrician book.  I remember directions for making an electrolytic
rectifier, what the hams used to call "slop jar" rectifiers, used before
they had tube rectifiers.  And for making a lead/acid battery, and for
making a photocell using, as I recall, copper oxide.  A later edition
tells about making a selenium photocell.

But I was not aware of the Teletype connection until my younger friend
mentioned it and showed me the book that had been given to him as a
youngster.