There is an example of a simple monkey automaton on my calliope page,
http://rpartos.org/calliope.html 

The drum beater stick is what actually moves, pulling the monkey's
arm back and forth.  It is activated by sound and was built using the
innards of a "dancing beer can"; these were a popular gag gift around
25 years ago.

Dick Partos
rpartos@cox.net.geentroep [delete ".geentroep" to reply]