In case anybody's interested, I bought one of those Dekatron Spinner kits from the place I linked a few posts above. I then made a circuit to interface it to an Arduino (or an Ian clock). I have one output that steps the Dekatron 1 position, and one input that tells the Arduino when the Dekatron is in the zero / home position. My test code advances the Dekatron rapidly to the zero position at power-up (since the Dekatron may power up in any random position). Then is just steps it one position per second. This is just test code - there are plenty of things that could be done to the Dekatron with additional programming.
I used 2 transistors (a MPSA42 and a MPSA92), 2 opto-isolators and a handful of resistors. I used what I had on hand. With HV tolerant optos (like are used in several of Ian's kits for anode drive) I could probably simplify it a bit.
Look into it later when the dust is clearing off the crater.
I emailed Ian, but havent heard back - he is likely busy.
I have questions around the Wifi Module and where the SMDs etc go for that. Also the wiring for the Microwave unit, how that ties in.
Outside of that, I have just begun to build the unit, and the Red LED1 from the Low Voltage part wasn't in very good nick when it arrived (one leg basically fell off) happy to get one here, however I dont know the specs of the unit. I know its likely a common 3mm Red LED, but voltage, current etc. Can anyone shed some light on this?