Quote Originally Posted by Darrel Taylor View Post
skimask,

A quick look at the datasheet would have shown that the ULN2004 does have Output Clamp Diodes. Datasheet boy.

Joel,

Maybe you need a snubber on the relay driving the contactor.
I use .022uF 400V and a 47ohm 1/2w resistor in series across the output, but then I'm using SSR's

Works good for all the contactors I've used.
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Ya I know, I just downloaded it and looked That'll learn me for not learnin' me...
But still, what if the '2004 isn't right next to the relays? What if it's on the PCB and the relay is X feet down the road on a cable.
Maybe an opti-iso would be the ticket in this case...still doesn't resolve the relay spike but it might isolate it a bit better...
How 'bout a decent cap across MCLR? If there's a pullup on MCLR, maybe it's being dropped out on occassion?