Back when I was still working (electrician) I worked some time in computer rooms servicing A/C units. When a compressor would burn out, I would scavenge the small tubular crankcase heater from it. Drilled a 3/8" hole in a piece of 1/2" aluminum plate and shaped it to the footprint of the lube-sizer, bolted the two pieces together on the bench. Works quite well on 120 volts.