I've been following with at least one eyeball, the discussion of firing
MOSFET's from a PIC.  Got thinking about something I've been wanting to play
with, but it deals more with a current ramping.

Lets say I want to inject a DC current into a pair of motor windings (this
is basically called dynamic braking).  I've done this in the past, but
always just dumped it into the windings for a set period of time.  Taken a
110 VAC signal, ran it thru a 25A bridge, and then a power resistor (big one
with the aluminum heatsink) to limit the current, and then ran it through a
relay for a second or two.

But I wonder....is it possible to ramp the current with something?  I'd need
a device capable of probably somewhere around 10A, and I want to ramp the
current down to zero, or maybe even at least half of what it starts with.
Measure the current using a A/D input, calculate the ramp and then....insert
magic device.....and then ramp it down to some calculated value.

So, any of you smart folks know of a device that I can ramp the current,
probably based on some voltage on the gate (so now we need a D/A, but thats
ok).  I think what I am looking for is something that the resistance of the
source to drain can vary as a function of the voltage on the gate?