I think a simpler explanation of "emf" is to use the analogy of momentum and inertia. When you suddenly stop (turn off) the electric (DC) going to a coil (solenoid) the electric is still going (inertia). When it finally stops it "piles up" and arcs across whatever has a low breakdown voltage like a capacitor with a low rating. This is a very simplistic but easy to understand description of events. The idea of the "fix" is to allow the electric to "bleed off" harmlessly without damaging anything. In reality the problem is not exactly reverse emf but the sudden shutdown of the circuit without an allowance for the release of the "left over" electric which as Walt said was the magnetic field. Reverse emf is a term applied to the effect observed more commonly in motors. David Teitelbaum vin 10757 --- In dmcnews@xxxx, "Walter" <Whalt@xxxx> wrote: > > >Is anyone familiar with the theory of reverse EMF occurring on the computer > >governor? >