On 2008-09-26, Pete C. wrote:

Winston wrote:

[ ... ]

Genius is recognizing the obvious before everyone else.
It should be rewarded.

--Winston

Inventing a practical electric light - Genius
Inventing the telephone - Genius
Applying a timer to windshield wipers to do what people were already
doing manually - Obvious

The intermittent windshield wiper became practical when SCRs
(Silicon Controlled Rectifiers) or power transistors and circuits like
the 555 timer chip became inexpensive enough. The windshield wiper
motor already had a set of contacts to open the circuit when the wipers
reached the "park" position. All that was necessary was to kick the
wipers on for a moment (through the "run" wire) to get past the park
position, and then sit back to wait for it to park at the end of a
single wipe. Then wait an adjustable time and kick again. Since the
park contacts were not designed for that frequent a use (just once when
you turned off the wipers when the rain went away) adding solid state
components to it made it more reliable so you could depend on that to
work.

Enjoy,
DoN.

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