A Simple, Valve Curve Plotter

[SurreyNick]

I think it's going to be one of those 'suck it and see' situations. Most of these early valves are of the 2v or 4v type, drawing a filament current of between 0.1A and 1A. I might have to reconsider the max resistance of the potentiometer as I may need to go up to 50 ohms, but 2W is the max power for any of the most common valves I'm going to encounter.
Nick