what transistor for ignition coil?

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#1
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Hello
I have finish a project with avr ,electronic ignition with adjustable advance, for one cylinder engine.
The ignition coil from this engines is connected to ground and ignition module switching the positive.
I have make my test with standard bipolar transistor and work but not as we like to work ,we don't have enough current to coil ,comparing with oem ignition module.
I am thinking to use p channel mosfet transistor, because mosfet have low resistance from source to drain, in parallel but i don't know what type to use there are a million types out there.
Avr give high output for every pulse so I use first npn transistor to drive power pnp transitor or p channel mosfet
Thank you

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There are devices specific for ignition applications. Bosch, ST and infineon have such items. If you have a look at the megasquirt website, there is much discussion about driving ignition coils.
FYI, normally the 0V side of the coil is switched so you would use a npn or n channel mosfet/igbt.

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I have found many special design transistor for ifnition coil but all is npn.
I have to swtch the positive side so i need pnp

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Why do you want to switch the positive when the common method is to switch the negative? The lack of specialist devices suggest anything to you?

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All the mini bikes like honda inovva ,lifan motors yamaha etc on little bikes use possitive switching side.
In my bike i can make it with negative no problem for me but what to tell a customer who will buy my electric module to change the coil connection?
I have to make it plug and play.

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thanks rickb i didnt think to search before for cdi.