I thought that there were more pics in this thread showing a popper with the thermocouple probe and digital thermometer, but they must be in other threads. Sorry, I should rectify that.
"Temperature's what's important to monitor when you do a profile"
Yes it is - but I like to establish a pattern for my roasts based on regular voltage increases to achieve the temp profile that I want.
That way I don't have watch the temp every second of the roast, with my hand poised over the knob, making adjustments on the fly.
I have a pattern for my preferred profile for most beans, but I also have one longer slower roasts, & another for shorter faster roasts.
Using these, I choose my start voltage and increase it at one minute intervals to get the required profile.
That's the main reason why I added the voltmeters.
"I was hoping you'd draw up a sketch with values"
I would, but some components have no markings, & others would have to be removed from the board to be able to read them.
These things are as cheap as chips. If I was in your situation I would buy one and try it on 120V. If they work - that's great, if not, you can dismantle and measure values, then maybe modify it if needed. If it's a write-off, its only a few bucks.
One of them from ebay seller "sitedv88" Item SKU: 14_S000114008967 specifies :- Voltage 110 - 220v Voltage control 50 - 220v.