[ Ref. https://www.mmdigest.com/Gallery/Tech/humes_UnitValve.html 
 [ https://www.mmdigest.com/archives/Digests/200702/2007.02.17.06.html 

I have read Bob Humes' notes on "Making Wurlitzer Unit Valves" many
times, and I recall a smaller PDF document that detailed exactly how a
unit valve works. I remember it noted one of the holes must be 5 times
the diameter of another hole. Can someone help me find this PDF?

Jeff Kunkel