I'm thinking about using the Futaba VFD as the preamp for a tiny (2W or so) guitar amp. Guitar-amp power transformers have secondaries for both high voltage (for the tube anodes) and low voltage (for filaments). Convenient, but seems like overkill for the feeble needs of this project, so I dug into my transformer stash. There, Hammond Schmammond:

To the left is an HVAC-control transformer that will provide isolation and lowish voltage. To the right is what looks like an answering-machine power supply. Let's crack it open:

Except for some rust and glue on the core, and copper peeking through the insulation on the mains-voltage wires, this transformer is fit for duty. So here's the configuration I have in mind:

From left to right. Meet Shiny (HVAC-control transformer) and Rusty (the answering-machine transformer). Put mains voltage (120 Vrms) across Shiny's 208 V primary (white and red wires) to get about 14 V across the secondary (blue and yellow, Slava Ukraini). This isolated low-voltage AC will be rectified and regulated to provide clean DC for the filaments. It will also be used to as input to Rusty's low-voltage coil. If all goes well, we should then get about 170 Vrms across Rusty's high-voltage coil that we can rectify and regulate and use for B+.

The parts on my bench, lashed up and ready for testing:

No regulation yet, Rusty's AC output is converted to ugly DC (with significant hum) using just a bridge rectifier and a reservoir cap (2.2 mF, 200 V). Here's the DC output voltage vs. load current:

For the preferred operating point (OP1) we want 157 V of clean (regulated) DC. I reckon we'll need ugly DC of about 170 V (the yellow box in the plot) into the voltage regulator. That makes the power budget a bit tight (2 - 2.5 W). For the alternative operating point (OP2, marked by red box), about 155 V of ugly DC should do, increasing the power budget to a comfortable 4 W.

One more watt would have been nice, but I think Shiny and Rusty will have to do.