This project was inspired by a large isolation transformer I found at a very low price and my need for a dual AC source. The chassis came from an old Altec Lansing amplifier that I purchased for $10. I used a soft-start module from eBay, which I had to modify to operate on 120 VAC since I hadn’t noticed the original specifications when I bought it. The isolation transformer provides two isolated 120 V outputs, each connected to a variable transformer through a relay board controlled by an Arduino Nano. The output voltage and current are monitored using two LCD modules from Amazon. I didn’t spend much time on documentation, but I do have a simple working sketch.

Schematic diagram and modification for the soft start module is shown below.

Add 1.8uF/450V capacitor to the capacitor circled in red.