[GreenKeys] Range and Bias

[George B. Hutchison]

Jeff - - -

Excellent explanation of the operation of any selector.

The only comment I have is that the additional length of the stop 
pulse was not for selector "settlling", but for the fact that early 
on machines were in locations where the power could have been DC, 25 
cycles, 50 cycles or 60 cycles.

This would mean that all of the machines in a given network, which 
could have had units with all of the above mentioned power supply 
frequencies, minor variations thereof, etc.,  resulting in every 
mainshaft in the network running at a slightly different speed.

The long stop pulse allowed the machines to re-synchronize with the 
source.

Sorta like a hundred yard dash. Everybody starts at the same time 
from the same point. But some tracks may be concrete, some turf, 
some gravel, and let's throw in some sand for good measure. Everyone 
would get to the finish line, but at different times.

Were they to run the race again, odds are that averaged out, the 
same performance would recur on each different track after maybe ten 
races.

The long stop pulse allows all the runners to go again from the same 
bang of the starter's pistol.

You done good, pal...

W7TTY