A project that started with exploration of VFD (vacuum fluorescent display) has evolved into a fun little project the Death Clock. Emily has an aesthetic in mind for its external enclosure and I’m fully on board with it. What’s inside the box will be dictated by the priorities we’ve agreed on. The overriding theme is focus: we’ve spent a lot of time and effort getting this far, let’s focus on putting it in use and not get distracted.
For the power system, we will use parts from the original device as we’ve done in our experiments so far. This means the original transformer, rectifier module, and several capacitors. There was the temptation to turn this into a battery-powered contraption for better portability and easier show-and-telling, but that’s a distraction today. We can tackle battery power for a future VFD project.
For the control system, we will use the exploratory control board we’ve rigged up. It is a simple circuit with an 8-bit PIC driving three ULN2003A Darlington arrays. Plus a 3-to-8 bit decoder to help with grid control. We started looking at the Microchip HV5812, a control chip designed specifically for driving VFDs, but that’s a distraction today. We can consider that chip for a future VFD project.
And finally, staying with the theme meant the simple software running on the PIC will remain as-is. I had considered adding the capability to control brightness of individual segments: fade effects are rarely seen in old VFD screens and I thought it would be a fun differentiator between old and new. But again that would be a distraction now and I can pursue it later. Potentially in conjunction with Microchip HV5812 above.
Keeping it simple and avoid feature creep. That’s the key to finishing projects instead of letting them drag on forever.