Amplifier with Horisontal Optical Switch

The PMA50 power module has a voltage overhead of about 1.5V.  If the battery is reading 12V the voltage across the coil will be about 10.5V

On the PMA50 / PMA60 / PMAZ power module the dwell angle is fixed by the length of the chopper blade.  The chopper blade length is set by the number of cylinders with a ratio of about 35% coil "Off" to 65% coil "On".

As the blade is a fixed length, when engine RPM increases the coil switch "On" time decreases.  To work out the coil "On" time you need to know the engine RPM and the number of cylinders.  The formula is:

60,000 / RPM / no. of cylinders * 0.65 = coil charge time in ms

So for a 4 cylinder engine at 8,000 RPM the coil charge time will be about 1.22 ms

On the Performance system (CEK150 / CEM) the power module automatically changes the dwell angle of the coil depending on the coil fitted, the number of cylinders and the engine RPM.