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Preliminary schematics

A project log for Guri: Ignition Controller for Air Cooled Engines

Ignition controller for VW air cooled engines.

danjovicdanjovic 04/18/2016 at 16:443 Comments

First schematics, fresh out of the oven. Used only one voltage regulator, though.

Discussions

danjovic wrote 04/18/2016 at 18:30 point

Hi, K.C. thanks for commenting. This particular IGBT (IRGB14C40) already have the pulldowns but I'll keep an eye on the turn off time. As for the series resistor in Q5 base I missed that when I borrowed the protection circuit from mr. Chan's power incutor tester. I will also look for the MIC291xx regulators. Thanks! 

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K.C. Lee wrote 04/18/2016 at 16:59 point

You'll need to have a pull down for Q2 output.  Unlike a BJT, the gate of the IGBT (?) is like a MOSFET so you'll need a way to discharge the huge gate capacitance to turn it off.

Probably a good idea to have a series resistor in the base of Q5 as it'll take a long time to turn off the IGBT and until then the B-E junction might get too much voltage.  You should add a RC filter to catchglitches.

I highly recommend the MIC291XX LDO for automotive environment.  They have very good input protection against over voltage (load dump) and reverse voltage (jump start with the wrong polarity).

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danjovic wrote 04/18/2016 at 20:54 point

Hi, K.C. thanks for commenting. This particular IGBT (IRGB14C40) already have the pulldowns but I'll keep an eye on the turn off time. As for the series resistor in Q5 base I missed that when I borrowed the protection circuit from mr. Chan's power incutor tester. I will also look for the MIC291xx regulators. Thanks!

  Are you sure? yes | no