Hi Bill,
I believe there are 11 steps which are (in ohms) 31 (full), 28.4, 25.1, 21.7, 18.3, 15 (half tank), 11.6, 8.3, 5, 2.7 and .4~.5 ohm (empty). I will have to dig out my notes, but when I constructed one of these I think I only ended up being able to fit 10 steps into the tube. Obviously if the same number of steps can be built into a shorter tube (which for the gentleman who had the 7 inch tall tank will be the case) the needle movement will be smoother. I don't know if that will be possible, though. It will require some very compact components. The wiring, the reed switches and the resistors take up a certain amount of space and at the end of the day you do run out of room inside the tube...or at least I did. However I do see a possible benefit to the (roughly) 3 ohm steps the unit takes: the needle may be less susceptible to movement from motion, turns, etc. and some may find that a positive. As you know common values of resistors don't always allow you to hit exact step-down values, but this is pretty close. The more I've fiddled with it, the more pleased I am. Somebody did some nice work here it seems and it could last a very long time without problems.
