varying degrees of fractional rotation with master controller...

I have several elements in a grid pattern on my screen. I'd like to attach all of them to a master rotation controller, while limiting them to 180º of rotation in either direction, even when the master controller goes beyond 180º. I can create varying levels of rotation by multiplying by a fraction, ( .9, .8, .7 . 5 etc.)

Heres where it starts to get beyond my knowledge; How can I control the rotation of each object of the grid based on the position of… something like a null?

One of the results we are looking for is a 'magnetic' feel of the objects moving (rotating) as a reaction to an invisible object. Maybe have the strength of the 'megnteicism' be related  to the scale of the invisible object?

I'm trying to absorb as much as I can from Dan Ebberts site, but it's a bit much all at once...