A Simple, Valve Curve Plotter

[AlanBeckett]

That LR8 is an interesting Gadget Lawrence. I'll have to have a further look. I've pondered on modifying my Solartron HVPSU and that could just do it neatly. 

Transformers with a 6.3 and 5V Winding are pretty common, and there are ones with 6.3 and 4V. Pye were prone to using AZ31 in some of their Sets.

Alan