A Simple, Valve Curve Plotter

[pwdrive]

Maybe one of these:

http://www.vvttransformers.co.uk/vth1221...asheet.htm

Not sure how much they are.

Secondaries:

HT: 250-0-250v

Heaters: A) 0-4-5-6.3v
    "     : B) 6.3v center tapped.

1.4v and 2v valve heaters could be done via pot via from one half of the 6.3v winding (3.15v) If Ac can be used for normally DC heater valves then this transformer might do...Maybe.

Not trying to convince anyone, just putting ideas into the hat.

Lawrence.

Crunching some numbers on the above:

1.4v heater at 25 ma, R = 70 ohms, Pd = 175 mw

2v heater at 250 ma, R = 4.6 ohms, Pd = 287 mw

A 100 ohm pot might do and the derating might be ok, failing that a couple or so of switched resistors and a lower value pot, that would give an even better chance regarding derating the pot.

All other heater voltages would be straight off the transformer, the two 6.3v windings could be switched in series for valves with 12v heaters.

Just another thought.

Lawrence.