| SINGLE TRANSISTOR DRIVER FOR IGNITION COILS (RESONANT MODE) |
| Can an ignition coil be driven in resonant mode with a single transistor (I used an IGBT) driver? YES. The feedback coil is wound on the metalic case of the coil. The coil types, as you see in the picture (oil- insulated) are very good for this purpose. The transistor (FET or IGBT) has to be mounted on a big heatsink, adding a cooler is better. The output is stronger if higher capacity C is used. It works more stable and the IGBT doesn't heat to much if the cap is small (under 1 uF). |
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| ELECTRICAL SCHEMA |
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| The spark appearence depends by the cap C: |
| C = 470 nF @ 400 V : thin arcs, 2 cm long |
| C = 3.8 uF @ 400 V: strong sparks around HV output |
| Next step: it would be nice to try with tubes instead solid state. |
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| CONCLUSION: no practical application, because the transistor heats a lot limiting the time run. For higher voltage input, the coil saturate and become hot very quickly. With small C values, better cooling, short runs, the driver can work properly. |