Knock Sensor Bolt Heads. 8-)

[John Dammeyer]

Ha ha ha... reading bolt heads... cute...  8-)

Actually they are magnets.  One set as North and the other 34 degrees later
as South.  The pickups are Hall Effect latching sensors where one pole
latches them on and the opposite pole unlatches them.  They are on at 34
degrees before TDC and off at TDC.   Time from BDC to the 34 degree sensor
tells engine RPM to uC and depending on RPM electronic points are opened
between 34 degrees and TDC.   Simple PIC 16C54 application.

There is also a PIC 12C508 that translates the engine RPM pulses into pulses
divided by 2.4 to create a propellor RPM output since some pilots go snake
when they see any RPM over about 2800.

The knock circuit is there and retards the timer if the Bosch Knock Detector
(Volkswagen Junk yard stuff) is installed but we found we never needed it.

Regarding not finding the pages of the article on knock detection I quote:

"If you're interested in an article published in Contact Magazine on Knock
detection click on page1 or page2.
"
Should I have displayed that sentence in larger type and bold face?  ;-)

John Dammeyer

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