Mon Jan 19, 2015 9:47 pm
Your best option is a Variac, but, Iv'e used a regular lighting dimmer on my Model D. Just don't leave it on anything lower than 120 for very long.
Proud owner of a Gridfaced Thunderbolt 2000, Thunderbolt 1000 and 1000T, two SD-10's, and a Federal Electric Model D.
-Joshua H.