Mike,

Use what ever you think it is right for you.
Have you done any ECU project? That works fine

Andre Abelian





-----Original Message-----
>
> 2. use opto isolator to drive your replay never connect direct
>
What does this achieve?  The high current side of the relay is already
(hopefully) isolated from the coil.  Adding a diode to prevent back EMF
spikes from destroying the driver should be enough protection.  I have
dismantled many OEM automotive electronic modules and I've never seen a
manufacturer resort to opto-isolators to drive a simple relay, even
extremely inductive components such as the ignition coil and injectors
don't
appear to be opto-isolated within the ECU.

Regards

Mike

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http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.