You Blokes are too young to know
but.....
The nickel on the needle concept
came from the days when scratching
was just begining. Seeing that it
started from the ghetto, the DJs
couldn't afford Technics 1200s.
So, they made with what they had.
Their mothers phonograph (Turntable)
Seeing that these were not designed
for this type of function (Scratching)
The tone arm was very light. So,
to increase the weight, some would
use a penny, nickel, even a quarter!
The Phonographs used resemble these..
http://www.amstarrealty.com/graphics/03turncp.jpg
Cheers.