The display consists of a sequence of 8 DM160 fluorescent triodes that show the progress of a 3sec wave through the 4 taps or the ladder in a classic 4xRC Phase Shift Oscillator.
The DM160 has an intrinsic gain of about 10, which is just enough to drive the 4 tap RC lead ladder. Only the frist tube on the left is the the Oscillator.
The next three tubes are driven by attenuated versions of each of the other 3 taps on the ladder. This attenuation is necessary to make the grid amplitude the same comming from any tap.
The remaining 4 tubes get driven from the plates of the first 4 to complete the circle.
All told, the 8 tubes complete 360o of the 3 second sinewave in 45o steps.
I picked a 3second period for a kind of Lava Lamp feel. You may notice the use of 8 trimpots to match up the grid offsets of each tube.
The tiny DM160 triodes came from a past ebay auction in a lot of 12. Only 9 were good, so I have one spare for this 8 tube display.
There is a lot of variation from tube to tube. In addition to adjusting the grid offsets with the 10 trimpots, you will need to tweak the signal amplitude at the grid.
The amplitude for the oscillation tube is controlled by the pot on it's plate.
The amplitude for the 3 tubes tapping off the ladder is controlled by ratio of the resistors on the 3 legs of the ladder.
The amplitude for the 4 inverted tubes is controlled by the valued of the plate resistors on the firs 4 tubes.
Enjoy,
Joe
Approximate schematic originally entered in LTC SwitcherCAD
Photos of built 8 octant display of 4 phase lead RC network Phase Shift oscillator.
Phase_Shift_Oscillator Quicktime movies