Quote:
Originally Posted by Al Schober
Spark ignition using points & condenser is a strange beast.
The coil is a transformer and generates the high voltage. The low voltage winding of the coil is connected to the + and - terminals. The high voltage winding goes to the terminal on the top and the - terminal. It does NOT go to the case of the coil. So ask yourself - how does the spark energy get from the spark plug back to the - terminal? The answer is: Through the condenser! It can't go through the points as the points are open.
Please don't ask me to explain electronic ignition.
|
There are two kinds:
One acts as electronic points. The functionality is the same as mechanical points. They tend to burn out coils, they are "better" than moving metal around and can give you longer dwell. This is great for high RPM hotrods and terrible for a low RPM boat engine. There is a lot in the A4 archives about this and discovering the correct resistance for coils.
Next up is adaptive dwell, this system is also "electronic points" but changes the dwell on the fly to be kinder to coils.
Lastly are the variations on capacitive discharge, aka CD, ignitions. They work like a camera flash, the energy is not stored in the coils it is stored in capacitors that discharge into the coil.
Here is a scope photo from connecting it to my coil:
The big oscillations are the coil firing and the little one is the points closing again.