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Sine waves

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patrick1:
how many cyl is the car ?...  because using a single magnet / pickup is dangerous, - if it missfires once, then you might blow the engine.

safer too use one pickup for each cyl

i have same issue with a homemade electric motor, - which has 4 stages of power, - north,off,south,off etc etc   ... and i use a 4017 decade counter... worth a look if your not familiar, - good for a single hall effect trigger system....    but as i say, if you can have one per cyl it will be safer.

Mjolinor:

Two cylinder. BMW R75/6 1976. It uses wasted spark with two series six volt coils.

patrick1:
if i were you, and the current system is still  in place and working.

i would use opamps too determine sine wave TDC,  and set the comparator pin too a lower voltage too ovoid starting issues.

and the output of those analog devices, can trigger a 2n3055 too dump a capacitor onto the ign coil.


unless you wanted too take the high voltage plasma route ?...  then just stick another capacitor across the spark gap, charged by an inverter via 20kv diodes....  always need overkill on the diode front i find.  - but simplicity is better. - counting steps between pulses is a recipe for anziety

mikerj:

--- Quote from: patrick1 on September 07, 2019, 01:59:28 pm ---if i were you, and the current system is still  in place and working.

i would use opamps too determine sine wave TDC,  and set the comparator pin too a lower voltage too ovoid starting issues.

and the output of those analog devices, can trigger a 2n3055 too dump a capacitor onto the ign coil.
--- End quote ---

A 2N3055 is a very poor choice with it's low gain and low Vcemax  (~100v), and pretty much useless for a CDI system.

A sinusoid is also poor choice to trigger an ignition system from, the slower the trigger signal moves the greater the jitter you get on triggering.

Mjolinor:
I am using one of these for driving the coils:
https://www.ebay.co.uk/itm/Bmw-R80-R100-R65-Mono-Ignition-Amplifier-Gs-Rt-Rs-Bosch/133153082887?hash=item1f008ace07:g:SKYAAOSw9GRdZVAc

Pretty standard Bosch trigger do dad as used on a lot of vehicles.

I do have it all working fine with a hall effect but I am having difficulty getting exactly 180 degrees apart for the two sparks per cam rev. That is why I thought I would use a pair of coils in series because manufacturing tolerances can be nulled.

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