> take about 90VDC to light up, but after they light up they'll stay on > until the voltage drops below 60VDC or so. Only problems are: > > 1. The thresholds can vary greatly from unit to unit. > > 2. The thresholds will vary depending on ambient light, as well.

Use pulse coupleing so each runs at it's range. Also I do have a basic design for a TTT machine using neons and 2d21 thyratrons. I feel personally that would be good for demonstrating some for the other forms of logic used.

Then again someone would want that interfaced to PCI too.