MC3334 question

Michael Fawke fawkacs at ozemail.com.au
Tue Mar 5 22:54:26 GMT 1996


Pardon my ignorance, but I am a computer programmer and my knowlege of
analogue is _very_ limited....

On the MC3334, when used to drive an MJ10012 (?) with current sense, the
circuit diagram I have shows a .027 Ohm resistor bewteen ground and the 
MJ10012, with the sense taken from the MJ10012 side. In Tim Drury's article
on Distributorless ignition, he gives a circuit for the ignitor which does
not have this resistor. I am assuming the resistance is necessary for the
current sense to work, - so what can be used to create this resistance, or
can it really be discarded (as per Tim Drury's design)?

Also, how do you pick a coil to work with this design? Most coils I have
seen (single output) are sold with no info on resistance. Can the M3334 (when
used with current sense) use _any_ coil? I am currently using a coil with 
a ballast resistor and would prefer not to fork out another $50 Australian
for another coil :)

Thanks in advance.

PS. Angle sensing using optical light/dark coding on a wheel is _really_
dark ages stuff. Missed pulse/Long pulse detection is much better.
At least if the sensor fails the whole system stops - what do you think
would happen with a binary encoded wheel? Ugh! - makes me shudder!

Michael Fawke
fawkacs at ozemail.com.au




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