Sorry 'bout the mt message folks!
Recently, while explored my dungeon (basement), I discovered a bunch of vacuum tubes that have been skulking there for many years. These things are cool! They can do almost anything that a transistor can do. Plus, they can light your way on a dark night, and they can keep you warm in the winter! ;)
Anyway, I have retrieved a bunch of these thermionic emissive devices from the dungeon so to play around with them. But because specs are not available for many of the tubes, I would first like to throw a "KISS" curve tracer together to use with my old o-scope (also retrieved from the dungeon).
For plate voltage / horizontal sweep, I can use a plate power transformer with an unfiltered half-wave rectifier. To read anode current (vertical sweep), I will just use a small value resistor on the cathode. (Diodes and triodes only -- I'll worry about tetrodes/pentodes later). A 12-volt filament transformer on a variac will take care of the filament.
Now, the grid supply is the problem. A simple variable power supply will give me one single sweep of a family of sweeps. But it would be nice to see the entire family at once. A ramp generator would skew the curves. What I need, is a circuit that will step the voltage up on each 60 hertz half-wave, then reset to zero after eight or ten voltage steps. I need a "Staircase Generator"!
Spider webs and dungeon dust has yielded several circuits from magazines like "Radio", "Popular Electronics", "Shortwave Craft" and "The Capacitor". I'net searches have given up many more. But, every one of the generators I have found work by clocking a series of flip-flops that have resistor networks connected to their outputs. That should to the trick of course, but.........
Lurking somewhere in the dungeon of my mind is a staircase generator circuit that uses not counters; but some kind of simple capacitor charge pump. Over the years, my mind-dungeon has become too dim to see the circuit clearly.
Can anybody shed some light? Does anybody know of such a circuit? Comments, suggestions, please!