A Simple, Valve Curve Plotter

[SurreyNick]

Fortunately I only need one valve base - a B5.

Almost without exception the valves used in the receivers I encounter have a B4 or B5 base and on the very rare occasion I might encounter a 7 pin valve I can just buy a tested example or get it tested.

Now, as far as I am aware pins 1-4 on the B4 and on the B5 bases are common to each other i.e. a, g1, f, f. Pin 5 is the only one that differs, being used for the Cathode on some valves and for Grid 2 on others. I was thinking therefore that I might be able to design the circuit in such a way that via a rotary switch I can select one of three options, namely; (i) pins 1-4 only, (ii) pins 1-4 including a Grid 2 path and, (iii) pins 1-4 including a Cathode path. However, if the voltage range for Cathode and Grid 2 are not too dissimilar then I could potentially get away with just two options i.e. with or without pin 5 live. Pins 1-4 will already have adjustable voltages via wire wound pots.

If I’m on the right track then this is going to be a lot simpler than having fly leads with plugs.

Nick