A Simple, Valve Curve Plotter

[Mark Hennessy]

I'd keep it really simple, flexible and safe by just using an external DC bench supply. No worries about power rheostats, variacs, custom transformers etc. All far too ccomplicated.  Two 4mm banana sockets and there you are. 

Yes, I agree...

I could find a spare PSU if you were stuck. One of these: http://golbornevintageradio.co.uk/forum/...p?tid=3766

To be honest, they are an essential part of any lab, and you can never have enough. They are also a really good project for beginners, as you can start simple and gradually add more sophistication as you learn more.