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newbie looking for help

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Old dog

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Giday everybody,
Hoping the collective mind of this forum can steer me in the right direction.
As the heading says, is been years since i did this,(TAFE).
Objective: looking to fire 2 LPG fuelled bird scare cannons using leftover car parts.
Parts: 1 DIS ignition module (that I have piggy backed on another motor and had sparking),
2 LS1 style coils (coil on plug), to fire cannons.
DIS supplies constant +12V and a switched ground. And the LS1 coils need +5V to trigger.
My thoughts so far; see .png below.

sorry, just seen that this sketch is old. Ignore the part marked DIS, and every thing after the 7474 chip:oops:
My question is am I heading in the right direction with the wiring of 7474 (or similar) so as to 1/2 the original clock streem, and alternate the o/p, you know,fire 1,fire 2,fire 1,fire 2,etc.....
 

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dr pepper

Well-Known Member
Most Helpful Member
Yes that looks as though it has a chance of working, you dont have to 1/2 the clock but it'll probably work like that.
However I'm not sure of the relavence of the dis module, if you are using c.o.p. modules you can fire them directly, they usually have 4 wires, power, ground, trigger and spark confirmation, if you apply power, ground and a 5v squarewave on the trigger the plug should fire, spark confirmation doesnt need connecting.
 

Old dog

New Member
thank Dr pepper,
yes. correct on all counts. the original idea was conceived over several beers, and that's what was laying around us at the time.
the next morning it became a local clock running off a car bat,direct firing the C.O.P.
I was just looking for confirmation or rebuttal, it's been 30 odd years since trade school. :sorry:
 

dr pepper

Well-Known Member
Most Helpful Member
No problem, glad it worked.
Later C.O.P.'s can get upset and refuse to spark if the pulse train isnt exactly what it expects as they are designed to provide constant energy sparks, hence the charge or dwell time of the coil is constant, so if the high or low time of the logical firing signal doesnt correspond with what the C.O.P. classes as a legal time period it will refuse to spark.
The 'spark initiated' output I seem to recall is only present on Toyota coils.
30 odd years ago we still had points ignition, you didnt need a computer to fix them, a leatherman was all you needed.
 
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