DMC optical sensor warning!

Tippie said:
The Ignitcec we use does not supply power to the coil +, just the pulse to the - side.
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Yes low side switched as we call it, an ignition switch to run/stop switch 12V supplied to the top of the coil or coils, opposite end of the primary is then low side modulated to maintain the average current desired or programed. If this modulation is not applied ( in the case of a transient spike into the control module ) then you would have 0,5 Ohms across battery volts or alternator volts, could take out the fuse, or coil or drive transistor.

The iis long box will work at 100% duty cycle into a dead short, flyback convertor have that ability to withstand abuse, there is pulse by pulse shutdown on the inverter stage, even with a dead short on the convertor the drawn current is no more than running current. Maximum of 1,5amps at 14,2v charge mode on the battery.

. The short box iis did supply the 12V to the ignition coil primary winding(s) common, this allowed me to use an inductive discharge small module or a high voltage convertor in the long box, ie the short iis module had 12V on the coil common, while the longbox had 350Vdc on the coil common.

By consequence i "proged" each harness to identify the type of engine the module was plugged into, ie you could plug a 120 series 2 module into a 180 series 1 or 2 motor and it would work seemlessly, while ignitec has many features, you can reprog the ignetec to do different motors...the iis just rode off while a laptop is sourced for the ignitech... had my advanced features in the day ( pre 2000 ), as ignitech has today, i did not need current limit to drive HKZ small ignition coils, the iis long box would drive any coil with any rating, 3,4,6,9,12V types as i did on a Trident with old boyer 3 by 4V coils in primary series... yes all three coils fired same time for all the plugs, real meaning to wasted spark, may have been a Lucas Rita, others may correct my recall.

Yes Tippie, many are the ways to have a clever outcome. j
 
not knowing ignetech parameters, if me i would limit at 3amps, no use in over saturating the magnetics of each coil. HTH j

*** me do simple... not often....smile.
 
I am assuming the Ignitech ignition is inductive and not capacitive discharge?

Assuming it is inductive, the amount of current flow in to the coil is not affected by how long it is turned on as once it is saturated, the coil is pure resistance. So whether it is on for 1 second or 10 seconds, the amount of current is the same. John's recommendation of limiting it to 3 amps is a good idea. Without current limiting, 14 volts in to a .5 Ohm coil is gonna take a lot of current! The current squared (28 Amps) times the resistance of the coil (.5 Ohms) would be 392 watts.

As the coil is also inductive, the current does not immediately go to a maximum value but ramps up as it is fighting the magnetic field the current flow is creating. Once coil saturation has been reached, keeping it on longer will not make a bigger spark but just makes the coil turn it in to heat. And as the motor rpm's increase you have less and less time to charge the coil so you need turn the current back on to the coil a very short time after the plug has fired. You can't do it immediately as although the spark at the plug looks like one single spark, it is actually oscillating and creating multiple sparks.
 
I don't know enough about how coils and igniter systems work to really understand it. My initial question related to the Gates toothed belt that drives my custom ND alternator (we're talking SF here, so replacing a Bosch dynamo with a Kwaka alternator) stripping out not long after I switched from 3ohm Dyna coils to 0.5ohm 'Plasma' coils from Fast Bike Gear in NZ. I've had tens of thousands of km out of one of those belts - this one lasted 800km. I'm going to a Micro-V belt in the hope it will last longer and carry high loads better - and cope with the uneven pulses and jerks of my 270 crank (especially at idle revs).
Whatever the Ignitech is doing it's doing it very well, because in concert with everything else that's contributed, I've had a very big jump in performance across a very wide powerband. On the dyno setting up the main jet for the FCRs it had a distinct breakup at very high RPM (around 7500). Now it is dead clean right through to rev limiter (8200).
 
Tippie said:
Hook up an ammeter and see what happens.
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This is were the technical fine detail comes into play, what you will read has a lot do do with the type of meter used to measure the varying applied drive, to the coils, not least being you will be measuring while the motor is running, as with digital ignitions we do nothing until the crank motions under a cold crank.

In the case of the iis, the coil pre saturate period is only 40 degrees of crank rotation, also while idling, up to 1250rpm, if you averaged the 3-4 amps over 360/40 = 9 say 4amps/9 = a measured current of 0,45Amps highly dependent on the meter doing the measurement, dual slope or true rms, et al the peak current ( as Bruce points out correctly ) will still be say 4 amps but only for one 9nth of the time until the next cycle begins. With 3 coils or 2, this duty cycle is sequenced, which increases the average current draw from the 12V supply buss. You may well see the meter jumping all over the place as it sees a complex waveform.

....whats that ... sorry you asked, dont be, all a matter of degrees... had to say that didnt i.... HTH j.
 
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