Changes by last author:
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| How can one set the dwell to his coil? |
| Dwell adjustment |
| measure current consumption |
| Measure current consumption |
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If you want (say) 120mJ spark, at 6000 RPM (100 crank rotations per sec) that means P = 120mJ * 200 / sec = 24W for a 4 cyl (2 sparks per crankrot). Preferrably do it on table first, as on OnlineCourse/OffEngineTesting. No need for all 2..4 coils of course, but consider this in the calculation: calculate with actual_number_of_transformers * actual_spark_freq (h[2] table comes to mind) instead of the 200 / sec above.
With 85% guesstimated efficiency and 14V supply you'll want to adjust dwell until you measure I = 24W / 0.85 / 14V = 2A average (mean) current (DVM in 10A .. 20A mode). |
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* for each measurement, take note of the RPM, because the current consumption is RPM dependent.
* take note of VBatt as well * also, don't forget to document as much of your setup as possible: ** config ** coil type; resistance; inductivity (if known) Connect 2* [0.1 Ohm 5W resistor] in parallel to get a 0.05 Ohm 10W resistor. Connect one of this in series with each ignition fuse and measure voltage with DVM across it (1A => 0.05V). If you want (say) 120mJ spark, at 3000 RPM (50 crank rotations per sec, 1 spark per crankrot with wasted spark coils => 50 sparks / sec) that means P = 120mJ * 50 / sec = 6W. Preferrably do it on table first, as on OnlineCourse/OffEngineTesting. If you cannot meausure the current of each transformer separately (eg. because there is a shared supply for 2 transformers eg. in an IgnitionPage/TransformerWithAmplifier ) multiply with the number of coils that are fed from the measured current (multiply with 2 in a 4cyl wasted spark setup). With 80% guesstimated efficiency and 14V supply you'll want to adjust dwell until you measure approximately I = 6W / 0.8 / 14V = 0.54A average (mean) current (at given 3000 RPM !!). That means 0.54A* 0.05 Ohm = 0.027V across the 0.05 Ohm power resistor. |
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| * IgnitionPage/TransformerWithAmplifier |