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PE0WDM > TECHNI 19.08.03 20:51l 39 Lines 2311 Bytes #999 (0) @ WW
BID : 43253_PI8CDR
Read: GUEST OE7FMI
Subj: thanks motorcycle e-ignition
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Sent: 030819/1833Z @:PI8CDR.#DRE.NLD.EU #:43253 [Beilen] $:43253_PI8CDR
From: PE0WDM@PI8CDR.#DRE.NLD.EU
To : TECHNI@WW
All who reacted, thank you very much for your advice.
The magazine 'Silicon chip' is not known here in Holland, alas.
I checked the internet site Dick, VK3ABK gave and indeed there are articles on this subject.
The use of a PIC16Fxx makes life easy for those who lnow how to handle those devices.
Alas, I am not (yet) one of them but I will look into the subject from that angle; you are never
too old to learn.... ;-)
For the pick-up device I can choose any option still. I suspect that a magnetic device will
do best in the harsh environment next to a vibrating crankshaft.
The automatic advance must be derived from the speed of the crankshaft (in rpm) since this
has to do with the time that is needed for the flammable mixture to fully burn after ignition
during the downward movement of the piston. the faster the machine runs, the less time is
available and the sooner the ignition needs to start. if not the still burning gasses will
leave the exhaust and the energy is wasted. besides this gives extra erosion of the exhaust.
The retarding of the ignition is done with a device that gets its information from the vacuum
in the inlet and serves to correct the timing for a sudden disruption of the ideal mexture when
the throttle is suddenly opened. this mixture has the tendency to give more of an explosion
than the desired 'fast burning' so the ignition time must be a bit later to prevent the full power
of the ignited mixture to be before the piston reaches its highest point thus pushing it back
instead of helping the machine forward. in my simple machine this device is not necessary
since the advance reaches from 10 (stationary) till 45 degrees (at max speed).
at 45 degr. I already run full throttle so there is no more acceleration then to be expected.
In the more modern motor management system the trigger pulses are derived from a toothed
disk in which the highest point of the piston is marked with a missing tooth. the computer
then does the rest. I would like to make a unit that only has one or at most 2 triggerpoints and
has preferrably no PIC or any other 'difficult' device. I will have a look at the MC3334 to see what
that can do.
I get the idea that this will be a project for the whole winter.
73 de pe0wdm, wim
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