Harold,

I'm curious why you don't just try your idea.  It looks reasonably sound 
and a quick test with a 555 (or suitable substitute) where it's easy to 
alter the frequency and duty cycle would get you a good answer in under 
an hour.  It seems that if you can use the existing pumps "as is", 
that's the way to go.  Go with plan 3 if there's any reasonable way to 
make it work.

Dave

>Thanks for the comments! Since there's going to be a PIC in the product to
>handle other stuff, I'm planning on having it drive a transistor or two to
>drive the pump. The trick is, should I:
>
>1. Rewind the pump using a center tapped coil and pulse each end of the
>coil to ground, or
>
>2. Rewind the pump with a single ended coil and pulse just one end to
>ground (mechanical resonance possibly would take it back the other way).
>
>3. Don't rewind the pump, but make the coil resonant so I can get enough
>current with low voltage drive (as mentioned in the article I posted
>previously in this thread).
>
>Again, THANKS for the comments!
>
>Harold
>
>
>  
>


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