ChronodeVFD, a Watch by @Johngineer #WearableWednesday


Lovely VFD wristwatch by John De Cristofaro!

The ChronodeVFD is a personal project I’ve been working on for a couple of months. It’s a wristwatch built around the IVL2-7/5 VFD display tube. I originally purchased a few of these tubes to build a standard desk clock, but after playing around with them, I realized I could probably build a wristwatch too. The tube has a number of features which make it more suited than most Soviet-surplus VFDs for this purpose.

  • nominal 60mA filament current @ 2.4V, but still works with ~35mA @ 1.2V.
  • It’s small — only 1.25 x 2.25″
  • It’s flat, as opposed to the round tubes like the IV-18, which would be much clunkier in a watch design.
  • can operate from a relatively low grid voltage of 12-13V (up to 24V)
  • pulls only about 2.5mA/segment from the grid rail @ 12.5V. (“8″ = 20mA)

One other feature that I like about this device is that unlike nearly every other VFD tube, the IVL2-7/5 has no opaque or diffuse backing behind the digits. It’s completely transparent front to back, which means that if you put it on top of a circuit board, you can (with a bit of backlighting) see the PCB below.

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  1. What a great design! Thanks for sharing.

  2. Great project John! Love it! Now when can we expect a kit? 🙂

  3. DROOL!!! Love your project! I second the kit comment above…

  4. Hey, I love it.

    A nice varient would be to remove the battery from the board and have a number of AA or AAA cells in parallel like a bandolier on the wrist strap.

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