FW: Buick DIS coil drivers

[john carroll]

I have been using these modules on aircraft engines for several years.  They are very 
easy to adapt to any thing.  You can even use one lead from one coil and run a single 
cylinder engine.  The best description I have found is from several pages in a GM 
training manual, publication 16009.10-1. Mine is dated 1986.  The operation of a 
number of other peripherals is covered as well as wiring diagrams and signal 
descriptions.

The coil base is controlled by several signals and emits a 6 pulse per revolution 
tachometer signal.

Timing comes from a notched disk that stimulates a cheap ($20) probe to produce a 
positive then negitive pulse at six symetrical locations pluss one additional, oddly spaced 
notch to track  tdc/tbc of cyl #1.  

If the signals from the controller are not acceptable, the device runs in limping mode 
that limits advance to about  10 degrees at 3000 rpm.  As a magneto replacement on 
aircraft we sometimes use the thing in this mode for ever by dumping in 15 degrees of 
fixed advance and letting the thing come up 10 degrees on its own.   In this mode the 
thing only needs power and a signal from the crank sensor to function.

The other signals used to control operation are BYPASS which tells the coil base to run 
on its own and an EST signal which I believe works like other GM EST signals.  These 
two signals are generated by the controller.  The coil base generates REF, a phase 
signal that indicates 60deg btdc.  Five volt CMOS signals control the device well.  TTL is 
a bit iffy.  If you want to distinguish between cylinders you will have to look at the cam 
with another sensor.

I use a GM MAP sensor and calculate and control advance with a Phillips/Signetics 
87c550.  I dump a continuous string of serial data to an RS232 port and update an 80 
character LCD device using about 25 percent of the controller resource at 3000 rpm

I could probably be persuaded to peddle some timing disks and copy some pages if 
people really need them for real projects.

--------------------------------------------------------------------------
john carroll
jac at wave.sheridan.wy.us

 >--------
>
>   I made some current and voltage measurements on a Buick 3.1L V6
>with a distributor-less ignition system this past weekend. 
>Three coils mounted on what appeared to be the driver module.
>
>The coil's waveform on the primary looked really good. Does anyone know 
>how to drive these modules? Is there an 8 cylinders 
>version? (use 2 4-cyl versions?)
>
>                                       John S Gwynne
>                                          Gwynne.1 at osu.edu
>___________________________________________________________________
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